This document summarizes pile foundations, including:
1. Piles are used when shallow foundations cannot support a structure due to soil conditions like depth of bearing capacity, soft/variable soils, steeply inclined strata, scouring, or high/variable loads. Piles transmit loads through skin friction and end bearing.
2. Piles are classified as driven/displacement piles which are preformed and inserted, or bored/replacement piles where a hole is bored and the pile formed within. Design considers shaft friction and end bearing. Load testing validates design calculations.
3. Analysis considers driving formulae or soil mechanics. Soil mechanics calculates shaft friction and end bearing resistance based on soil type, properties
- The document describes the design and detailing of flat slabs, which are concrete slabs supported directly by columns without beams.
- Key aspects covered include dimensional considerations, analysis methods, design for bending moments including division of panels and limiting negative moments, shear design and punching shear, deflection and crack control, and design procedures.
- An example problem is provided to illustrate the full design process for an internal panel with drops adjacent to edge panels.
The document discusses reinforced concrete columns, including their functions, failure modes, classifications, and design considerations. Columns primarily resist axial compression but may also experience bending moments. They can fail due to compression, buckling, or a combination. Design depends on whether the column is short or slender, braced or unbraced. Reinforcement is determined based on the loads applied, including axial load only, symmetrical beam loading, or loading in one or two bending directions. Links are included to prevent bar buckling. Examples show how to design column longitudinal reinforcement and links for different load cases.
Flat Plate Slab Design for B.Sc. in Civil Engg Students
By: Md.Mahbub Ul Alam, Asst Prof, Dept. of Civil Engg.
Stamford University Bangladesh.
Uploaded at www.sladeshare.net.
Reinforced concrete slabs are used in floors, roofs, and walls. They can span in one or two directions and be supported by beams, walls, or columns. This document discusses the design of reinforced concrete slabs, including types of slabs, load analysis, shear design, reinforcement details, and provides examples of designing solid slabs spanning in one direction. The goal is to teach students to properly design and analyze reinforced concrete slabs according to code.
This publication provides a concise compilation of selected rules in the Eurocode 8, together with relevant Cyprus National Annex, that relate to the design of common forms of concrete building structure in the South Europe. Rules from EN 1998-1-1 for global analysis, regularity criteria, type of analysis and verification checks are presented. Detail design rules for concrete beam, column and shear wall, from EN 1998-1-1 and EN1992-1-1 are presented. This guide covers the design of orthodox members in concrete frames. It does not cover design rules for steel frames. Certain practical limitations are given to the scope.
This document summarizes a lecture on flat slab design and analysis. It discusses key topics such as:
1. Definitions of flat slabs and their components like column strips and middle strips.
2. Methods of analyzing flat slabs including numerical methods and manual methods like the method of substitutive beams.
3. Design considerations for flat slabs including steel distribution above columns, welded mesh reinforcement, loading schemes, and punching shear design.
4. Different types of shear reinforcement that can be used at column heads like links, cages, and bent-up bars.
The document provides information on column design according to BS 8110-1:1997, including general recommendations, classifications of columns, effective length and minimum eccentricity, design moments, and design. Short columns have a length to height or breadth ratio less than 15 for braced or 10 for unbraced. Braced columns have lateral stability from walls or bracing. Additional moments are considered for slender or unbraced columns based on deflection. Design moments are calculated considering axial load and biaxial bending for different column classifications. Shear design also considers axial load and reinforcement is required if shear exceeds the shear capacity. The interaction diagram is constructed based on equilibrium equations relating stresses on a column cross section to axial load and bending
Lec.1 introduction to the theory of structures. types of structures, loads,Muthanna Abbu
This document provides an introduction to structural analysis and the theory of structures. It defines structural analysis as determining the response of a structure to loads through internal forces and deformations. It classifies skeletal structures and describes the different types of internal forces that can develop in structural members. The document also discusses structural loads, equilibrium, and reactions.
- The document describes the design and detailing of flat slabs, which are concrete slabs supported directly by columns without beams.
- Key aspects covered include dimensional considerations, analysis methods, design for bending moments including division of panels and limiting negative moments, shear design and punching shear, deflection and crack control, and design procedures.
- An example problem is provided to illustrate the full design process for an internal panel with drops adjacent to edge panels.
The document discusses reinforced concrete columns, including their functions, failure modes, classifications, and design considerations. Columns primarily resist axial compression but may also experience bending moments. They can fail due to compression, buckling, or a combination. Design depends on whether the column is short or slender, braced or unbraced. Reinforcement is determined based on the loads applied, including axial load only, symmetrical beam loading, or loading in one or two bending directions. Links are included to prevent bar buckling. Examples show how to design column longitudinal reinforcement and links for different load cases.
Flat Plate Slab Design for B.Sc. in Civil Engg Students
By: Md.Mahbub Ul Alam, Asst Prof, Dept. of Civil Engg.
Stamford University Bangladesh.
Uploaded at www.sladeshare.net.
Reinforced concrete slabs are used in floors, roofs, and walls. They can span in one or two directions and be supported by beams, walls, or columns. This document discusses the design of reinforced concrete slabs, including types of slabs, load analysis, shear design, reinforcement details, and provides examples of designing solid slabs spanning in one direction. The goal is to teach students to properly design and analyze reinforced concrete slabs according to code.
This publication provides a concise compilation of selected rules in the Eurocode 8, together with relevant Cyprus National Annex, that relate to the design of common forms of concrete building structure in the South Europe. Rules from EN 1998-1-1 for global analysis, regularity criteria, type of analysis and verification checks are presented. Detail design rules for concrete beam, column and shear wall, from EN 1998-1-1 and EN1992-1-1 are presented. This guide covers the design of orthodox members in concrete frames. It does not cover design rules for steel frames. Certain practical limitations are given to the scope.
This document summarizes a lecture on flat slab design and analysis. It discusses key topics such as:
1. Definitions of flat slabs and their components like column strips and middle strips.
2. Methods of analyzing flat slabs including numerical methods and manual methods like the method of substitutive beams.
3. Design considerations for flat slabs including steel distribution above columns, welded mesh reinforcement, loading schemes, and punching shear design.
4. Different types of shear reinforcement that can be used at column heads like links, cages, and bent-up bars.
The document provides information on column design according to BS 8110-1:1997, including general recommendations, classifications of columns, effective length and minimum eccentricity, design moments, and design. Short columns have a length to height or breadth ratio less than 15 for braced or 10 for unbraced. Braced columns have lateral stability from walls or bracing. Additional moments are considered for slender or unbraced columns based on deflection. Design moments are calculated considering axial load and biaxial bending for different column classifications. Shear design also considers axial load and reinforcement is required if shear exceeds the shear capacity. The interaction diagram is constructed based on equilibrium equations relating stresses on a column cross section to axial load and bending
Lec.1 introduction to the theory of structures. types of structures, loads,Muthanna Abbu
This document provides an introduction to structural analysis and the theory of structures. It defines structural analysis as determining the response of a structure to loads through internal forces and deformations. It classifies skeletal structures and describes the different types of internal forces that can develop in structural members. The document also discusses structural loads, equilibrium, and reactions.
This document discusses prying action in bolted steel connections. Prying action occurs when the deformation of connected elements under tension increases the tensile force in bolts. It is affected by the strength and stiffness of the connection. The document outlines how to design for prying action by ensuring sufficient bolt diameter, fitting thickness, and distance between bolts. It provides examples calculating the required thickness to prevent prying action. It concludes that prying forces should be considered in design and sufficient rigidity of connected elements is most important.
1) Two-way slabs are slabs that require reinforcement in two directions because bending occurs in both the longitudinal and transverse directions when the ratio of longest span to shortest span is less than 2.
2) The document discusses various types of two-way slabs and design methods, focusing on the direct design method (DDM).
3) Using the DDM, the total factored load is first calculated, then the total factored moment is distributed to positive and negative moments. The moments are further distributed to column and middle strips using factors that consider the slab and beam properties.
1. Reinforced masonry working stress design of flexural members uses assumptions including plane sections remaining plane after bending and neglecting all masonry in tension.
2. The balanced condition occurs when the extreme fiber stress in the masonry equals the allowable compressive stress and the tensile stress in reinforcement equals the allowable tensile stress.
3. Shear design of reinforced masonry considers mechanisms such as dowel action and the ability of shear reinforcement to restrict crack growth and resist tensile stresses. Allowable shear stresses depend on the presence of shear reinforcement.
Baf Shaheen College (B+12) ETABS Dynamic Analysis.pptxDES Engineers Ltd
The document discusses the structural design of a 12-story educational building in Dhaka, Bangladesh. It covers loading considerations including dead loads, live loads, wind loads, and seismic loads. Load combinations are listed. The structural system is described as intermediate moment-resisting frames. Manual and ETABS calculations are shown for wind loads in the X and Y directions and for seismic base shear, with a deviation of approximately 5% between the manual and ETABS results.
Manual for Detailing Reinforced Concrete Structures to EC20984
Detailing is an essential part of the design process. This thorough reference guide for the design of reinforced concrete structures is largely based on Eurocode 2 (EC2), plus other European design standards such as Eurocode 8 (EC8), where appropriate.
With its large format, double-page spread layout, this book systematically details 213 structural elements. These have been carefully selected by José Calavera to cover relevant elements used in practice. Each element is presented with a whole-page annotated model along with commentary and recommendations for the element concerned, as well as a summary of the appropriate Eurocode legislation with reference to further standards and literature. The book also comes with a CD-ROM containing AutoCAD files of all of the models, which can be directly developed and adapted for specific designs.
Its accessible and practical format makes the book an ideal handbook for professional engineers working with reinforced concrete, as well as for students who are training to become designers of concrete structures.
The document discusses code provisions for calculating the effective span of slabs according to IS 456. It describes how to calculate the effective span for simply supported, continuous, and cantilever members. It also discusses load assumptions, reinforcement cover requirements, deflection limits, and provides an overview of one-way slabs, two-way slabs, flat slabs, and flat plates.
This document discusses different types of retaining walls and their design considerations. It describes:
1. Gravity, cantilever, counterfort, and buttress retaining wall types based on their structural components and typical height ranges.
2. Design considerations for retaining walls including stability against overturning, sliding, and settlement; drainage; and structural design basis using load and safety factors.
3. An example problem showing calculations for earth pressure, restoring moments, and checking stability of a gravity wall.
Designing and drawing of flat slab with the help of i.s code Sandeep Yadav
This document is a mini project report submitted by Sandeep Kumar to fulfill the requirements for a Bachelor of Technology degree in Civil Engineering. The report describes designing and drawing a flat slab structure using the Indian Standard Code. It provides an introduction to flat slab construction, advantages of flat slabs like flexibility in design and reduced building height. It also discusses code regulations, design steps, and concludes with designing a flat slab according to the IS code.
The document provides steps for designing different structural elements:
1. Design of a beam subjected to torsion including calculation of torsional and bending moments, determination of steel requirements, and detailing.
2. Design of continuous beams involving calculation of bending moments and shears, reinforcement sizing, shear design, deflection check, and detailing including curtailment.
3. Design of circular water tanks with both flexible base and rigid base using approximate and IS code methods. This includes sizing hoop and vertical tension reinforcement, sizing wall thickness, designing cantilever sections and base slabs, and providing detailing diagrams.
The document discusses the design and construction considerations for reinforced concrete structures used in water utilities. It provides examples of structures like water tanks and describes advantages like durability and adaptability. The document outlines design factors to consider such as seismic loads, buoyancy, and security. It also discusses construction considerations including proper adherence to specifications, waterproofing, concrete mix design, placement, curing, and testing. Reinforced concrete requires proper engineering, construction practices, and ongoing maintenance to ensure long-term structural success.
This document discusses T-beams, which are more suitable than rectangular beams in reinforced concrete. There are two types of T-beams: monolithic and isolated. It provides notations and code recommendations for T-beams from IS: 456. There are three cases for finding the depth of the neutral axis in a T-beam: when it lies in the flange, in the rib, or at the junction. An example problem is worked through to find the moment of resistance for a given T-beam section using the provided concrete and steel properties.
This document discusses reinforced concrete columns. Columns act as vertical supports that transmit loads to foundations. Columns may fail due to compression failure, buckling, or a combination. Short columns are more prone to compression failure, while slender columns are more likely to buckle. Column sections can be square, circular, or rectangular. The dimensions and bracing affect whether a column is classified as short or slender. Longitudinal reinforcement and links are designed to resist axial loads and moments based on the column's effective height and end conditions. Design charts are used to determine reinforcement for columns with axial and uniaxial bending loads. Examples show how to design column reinforcement.
This document discusses the design of flat slab structures. It begins by defining a flat slab as a type of slab supported directly on columns without beams. It then provides details on the types of flat slabs, their common uses in buildings, and benefits such as flexibility in layout and reduced construction time. The document goes on to discuss key design considerations for flat slabs including thickness, drops, column heads, and methods of analysis. It focuses on the direct design method and provides limitations for its use.
Footings are structural members that support columns and walls and transmit their loads to the soil. Different types of footings include wall footings, isolated/single footings, combined footings, cantilever/strap footings, continuous footings, rafted/mat foundations, and pile caps. Footings must be designed to safely carry and transmit loads to the soil while meeting code requirements regarding bearing capacity, settlement, reinforcement, and shear strength. A proper footing design involves determining loads, allowable soil pressure, reinforcement requirements, and assessing settlement.
This document discusses the computation of parameters for designing reinforced concrete beams and one-way slabs. It outlines six assumptions made in the limit state design approach, including that plane sections remain plane after bending and concrete strain is limited to 0.0035. Three types of beams are described - rectangular, T, and L-beams. Equations of equilibrium are presented, including equations to calculate the total compression and tension forces, C and T. Parameters like the area of tension steel, effective depth, and neutral axis depth are also defined.
RCC design, Analysis of flanged beam, T beam, anna university, CE8501, Moment of resistance, neutral axis depth, Civil Engineering, design of beams, limit state method, IS 456, SP 16
This document discusses two-way slabs, which are supported on all four sides or at column centerlines. It describes two main types - edge supported slabs and column supported slabs. Edge supported slabs are suitable for spans of 20-30 feet and live loads of 60-120 psf. They have increased stiffness and low deflection. Column supported slabs include flat slabs and two-way ribbed/waffle slabs. Flat slabs have no beams or column capitals and are suitable for spans of 20-30 feet. Ribbed and waffle slabs have reduced dead load and architectural beauty, with spans of 30-48 feet and live loads of 60-120 psf. The document also discusses minimum
Design of flat plate slab and its Punching Shear Reinf.MD.MAHBUB UL ALAM
This document provides design considerations and an example problem for designing a flat plate slab using the Direct Design Method (DDM). It discusses slab thickness, load calculations, moment distribution, and reinforcement design for a sample four-story building with 16'x20' panels supported by 12" square columns. The design of panel S-4 is shown in detail, calculating loads, moments, and reinforcement requirements for the column and middle strips in both the long and short directions.
This document discusses the design of beams. It defines different types of beams like floor beams, girders, lintels, purlins, and rafters. It describes how beams are classified based on their support conditions as simply supported, cantilever, fixed, or continuous beams. Commonly used beam sections include universal beams, compound beams, and composite beams. The document also covers plastic analysis of beams, classification of beam sections, and failure modes of beams.
The document discusses reinforced concrete columns, including their functions, failure modes, classifications, and design considerations. Columns primarily resist axial compression but may also experience bending moments. They can fail due to compression, buckling, or a combination. Design depends on whether the column is short or slender, braced or unbraced. Reinforcement is designed based on the column's expected loads and dimensions using methods specified in design codes like BS 8110.
The pile foundation uses piles to support walls, piers, and other structures. Piles can be placed individually or in clusters. Piles are used when loose soil extends to great depths, and transfer structural loads to harder soils below through end bearing and side friction. Common pile materials include timber, steel, and concrete. Piles can be load bearing, transmitting loads through end bearing and side friction, or non-load bearing, used as retaining walls or sheeting. Pile capacity is assessed through field load tests or theoretical calculations based on soil properties.
This document discusses prying action in bolted steel connections. Prying action occurs when the deformation of connected elements under tension increases the tensile force in bolts. It is affected by the strength and stiffness of the connection. The document outlines how to design for prying action by ensuring sufficient bolt diameter, fitting thickness, and distance between bolts. It provides examples calculating the required thickness to prevent prying action. It concludes that prying forces should be considered in design and sufficient rigidity of connected elements is most important.
1) Two-way slabs are slabs that require reinforcement in two directions because bending occurs in both the longitudinal and transverse directions when the ratio of longest span to shortest span is less than 2.
2) The document discusses various types of two-way slabs and design methods, focusing on the direct design method (DDM).
3) Using the DDM, the total factored load is first calculated, then the total factored moment is distributed to positive and negative moments. The moments are further distributed to column and middle strips using factors that consider the slab and beam properties.
1. Reinforced masonry working stress design of flexural members uses assumptions including plane sections remaining plane after bending and neglecting all masonry in tension.
2. The balanced condition occurs when the extreme fiber stress in the masonry equals the allowable compressive stress and the tensile stress in reinforcement equals the allowable tensile stress.
3. Shear design of reinforced masonry considers mechanisms such as dowel action and the ability of shear reinforcement to restrict crack growth and resist tensile stresses. Allowable shear stresses depend on the presence of shear reinforcement.
Baf Shaheen College (B+12) ETABS Dynamic Analysis.pptxDES Engineers Ltd
The document discusses the structural design of a 12-story educational building in Dhaka, Bangladesh. It covers loading considerations including dead loads, live loads, wind loads, and seismic loads. Load combinations are listed. The structural system is described as intermediate moment-resisting frames. Manual and ETABS calculations are shown for wind loads in the X and Y directions and for seismic base shear, with a deviation of approximately 5% between the manual and ETABS results.
Manual for Detailing Reinforced Concrete Structures to EC20984
Detailing is an essential part of the design process. This thorough reference guide for the design of reinforced concrete structures is largely based on Eurocode 2 (EC2), plus other European design standards such as Eurocode 8 (EC8), where appropriate.
With its large format, double-page spread layout, this book systematically details 213 structural elements. These have been carefully selected by José Calavera to cover relevant elements used in practice. Each element is presented with a whole-page annotated model along with commentary and recommendations for the element concerned, as well as a summary of the appropriate Eurocode legislation with reference to further standards and literature. The book also comes with a CD-ROM containing AutoCAD files of all of the models, which can be directly developed and adapted for specific designs.
Its accessible and practical format makes the book an ideal handbook for professional engineers working with reinforced concrete, as well as for students who are training to become designers of concrete structures.
The document discusses code provisions for calculating the effective span of slabs according to IS 456. It describes how to calculate the effective span for simply supported, continuous, and cantilever members. It also discusses load assumptions, reinforcement cover requirements, deflection limits, and provides an overview of one-way slabs, two-way slabs, flat slabs, and flat plates.
This document discusses different types of retaining walls and their design considerations. It describes:
1. Gravity, cantilever, counterfort, and buttress retaining wall types based on their structural components and typical height ranges.
2. Design considerations for retaining walls including stability against overturning, sliding, and settlement; drainage; and structural design basis using load and safety factors.
3. An example problem showing calculations for earth pressure, restoring moments, and checking stability of a gravity wall.
Designing and drawing of flat slab with the help of i.s code Sandeep Yadav
This document is a mini project report submitted by Sandeep Kumar to fulfill the requirements for a Bachelor of Technology degree in Civil Engineering. The report describes designing and drawing a flat slab structure using the Indian Standard Code. It provides an introduction to flat slab construction, advantages of flat slabs like flexibility in design and reduced building height. It also discusses code regulations, design steps, and concludes with designing a flat slab according to the IS code.
The document provides steps for designing different structural elements:
1. Design of a beam subjected to torsion including calculation of torsional and bending moments, determination of steel requirements, and detailing.
2. Design of continuous beams involving calculation of bending moments and shears, reinforcement sizing, shear design, deflection check, and detailing including curtailment.
3. Design of circular water tanks with both flexible base and rigid base using approximate and IS code methods. This includes sizing hoop and vertical tension reinforcement, sizing wall thickness, designing cantilever sections and base slabs, and providing detailing diagrams.
The document discusses the design and construction considerations for reinforced concrete structures used in water utilities. It provides examples of structures like water tanks and describes advantages like durability and adaptability. The document outlines design factors to consider such as seismic loads, buoyancy, and security. It also discusses construction considerations including proper adherence to specifications, waterproofing, concrete mix design, placement, curing, and testing. Reinforced concrete requires proper engineering, construction practices, and ongoing maintenance to ensure long-term structural success.
This document discusses T-beams, which are more suitable than rectangular beams in reinforced concrete. There are two types of T-beams: monolithic and isolated. It provides notations and code recommendations for T-beams from IS: 456. There are three cases for finding the depth of the neutral axis in a T-beam: when it lies in the flange, in the rib, or at the junction. An example problem is worked through to find the moment of resistance for a given T-beam section using the provided concrete and steel properties.
This document discusses reinforced concrete columns. Columns act as vertical supports that transmit loads to foundations. Columns may fail due to compression failure, buckling, or a combination. Short columns are more prone to compression failure, while slender columns are more likely to buckle. Column sections can be square, circular, or rectangular. The dimensions and bracing affect whether a column is classified as short or slender. Longitudinal reinforcement and links are designed to resist axial loads and moments based on the column's effective height and end conditions. Design charts are used to determine reinforcement for columns with axial and uniaxial bending loads. Examples show how to design column reinforcement.
This document discusses the design of flat slab structures. It begins by defining a flat slab as a type of slab supported directly on columns without beams. It then provides details on the types of flat slabs, their common uses in buildings, and benefits such as flexibility in layout and reduced construction time. The document goes on to discuss key design considerations for flat slabs including thickness, drops, column heads, and methods of analysis. It focuses on the direct design method and provides limitations for its use.
Footings are structural members that support columns and walls and transmit their loads to the soil. Different types of footings include wall footings, isolated/single footings, combined footings, cantilever/strap footings, continuous footings, rafted/mat foundations, and pile caps. Footings must be designed to safely carry and transmit loads to the soil while meeting code requirements regarding bearing capacity, settlement, reinforcement, and shear strength. A proper footing design involves determining loads, allowable soil pressure, reinforcement requirements, and assessing settlement.
This document discusses the computation of parameters for designing reinforced concrete beams and one-way slabs. It outlines six assumptions made in the limit state design approach, including that plane sections remain plane after bending and concrete strain is limited to 0.0035. Three types of beams are described - rectangular, T, and L-beams. Equations of equilibrium are presented, including equations to calculate the total compression and tension forces, C and T. Parameters like the area of tension steel, effective depth, and neutral axis depth are also defined.
RCC design, Analysis of flanged beam, T beam, anna university, CE8501, Moment of resistance, neutral axis depth, Civil Engineering, design of beams, limit state method, IS 456, SP 16
This document discusses two-way slabs, which are supported on all four sides or at column centerlines. It describes two main types - edge supported slabs and column supported slabs. Edge supported slabs are suitable for spans of 20-30 feet and live loads of 60-120 psf. They have increased stiffness and low deflection. Column supported slabs include flat slabs and two-way ribbed/waffle slabs. Flat slabs have no beams or column capitals and are suitable for spans of 20-30 feet. Ribbed and waffle slabs have reduced dead load and architectural beauty, with spans of 30-48 feet and live loads of 60-120 psf. The document also discusses minimum
Design of flat plate slab and its Punching Shear Reinf.MD.MAHBUB UL ALAM
This document provides design considerations and an example problem for designing a flat plate slab using the Direct Design Method (DDM). It discusses slab thickness, load calculations, moment distribution, and reinforcement design for a sample four-story building with 16'x20' panels supported by 12" square columns. The design of panel S-4 is shown in detail, calculating loads, moments, and reinforcement requirements for the column and middle strips in both the long and short directions.
This document discusses the design of beams. It defines different types of beams like floor beams, girders, lintels, purlins, and rafters. It describes how beams are classified based on their support conditions as simply supported, cantilever, fixed, or continuous beams. Commonly used beam sections include universal beams, compound beams, and composite beams. The document also covers plastic analysis of beams, classification of beam sections, and failure modes of beams.
The document discusses reinforced concrete columns, including their functions, failure modes, classifications, and design considerations. Columns primarily resist axial compression but may also experience bending moments. They can fail due to compression, buckling, or a combination. Design depends on whether the column is short or slender, braced or unbraced. Reinforcement is designed based on the column's expected loads and dimensions using methods specified in design codes like BS 8110.
The pile foundation uses piles to support walls, piers, and other structures. Piles can be placed individually or in clusters. Piles are used when loose soil extends to great depths, and transfer structural loads to harder soils below through end bearing and side friction. Common pile materials include timber, steel, and concrete. Piles can be load bearing, transmitting loads through end bearing and side friction, or non-load bearing, used as retaining walls or sheeting. Pile capacity is assessed through field load tests or theoretical calculations based on soil properties.
This document provides information on pile foundations, including when they are used, their functions, types, and construction methods. Pile foundations are used when the soil at shallow depths does not have adequate bearing capacity. The key points are:
- Pile foundations transmit loads from structures to deeper, stronger soil layers through end bearing, friction, or both.
- They are used when shallow soils cannot support heavy loads, have low bearing capacity, or experience issues like high water levels.
- Piles can be made of concrete, timber, steel, or composites, and are either pre-cast or poured in place. Common types include end bearing, friction, compaction, and anchor piles.
This document provides information about pile foundations. Pile foundations are used when the soil cannot support building loads and piles are driven deep into the ground until they reach a bearing stratum. Piles can be made of timber, concrete, or steel. They transfer loads from the building to the stronger subsurface layer. The document discusses different types of piles including end bearing and friction piles and explains how pile caps are reinforced to resist tensile and shear forces from heavy loads. Diagrams show how pile foundations are arranged and how piles transmit loads into the ground.
This document lists and describes various types of piles that can be used for foundations, including timber piles, steel piles, H-beams, pipe piles, concrete piles, precast piles, prestressed piles, and composite piles made of plastic and steel. It provides references for more information on piledriving from websites like Piledrivinghelp.com and manuals from organizations like the US Army Corps of Engineers.
This document discusses different types of piles and their structural characteristics, including steel piles, concrete piles, timber piles, and composite piles. It describes methods of estimating pile length and capacity, including point bearing and friction piles. Equations are provided for estimating the ultimate load-carrying capacity of a pile from its point bearing capacity and frictional resistance. Methods are presented for calculating the point bearing capacity using approaches by Meyerhof, Vesic, and Janbu. The document also discusses estimating the frictional resistance of piles in sand and clay, including the lambda method for clay.
Piles are deep foundations used to transfer structural loads through weak or wet soils to stronger soils below. Piles can be classified based on function (end bearing, friction, tension), material (concrete, timber, steel), or installation method (driven, cast-in-place). Key factors in pile design include soil properties, load types, and groundwater conditions. The ultimate load capacity of a pile considers end bearing and side friction, while the allowable load uses a factor of safety. Dynamic testing and soil parameters can be used to estimate pile capacities.
Pile foundations use driven or bored piles to transfer structural loads to deeper, load-bearing soil strata. Piles are classified by their function (end bearing, friction, anchor piles), material (timber, concrete, steel), and installation method (driven, cast in situ). Pile foundations are used when bearing capacity is limited at shallow depths or in unstable soils like waterlogged or compressible soils. Selection depends on factors like subsurface conditions, structural loads, groundwater levels, and material availability and costs.
This document provides an overview of driven and bored piles. It defines piles as deep foundations that are driven into the ground. Driven piles are installed by driving them into the ground, while bored piles involve drilling a borehole and filling it with concrete. The document discusses pile types, installation methods, hammer types for driven piles, design considerations for different soil types, and advantages and disadvantages of each pile method.
This document discusses pile foundations. Piles are structural members made of materials like steel, concrete, or timber that are driven into the ground to support buildings on weak soils. There are two main types of piles: end bearing piles that extend to bedrock, and friction piles that gain support through friction in the soil when no bedrock is present. Pile caps are used to distribute loads from the structure to multiple piles. Reinforcement in the pile cap resists tensile and shear forces. The document provides schematics and comparisons of different pile foundation construction methods.
This document discusses different types of foundations used in construction. It describes pad, strip, raft, and pile foundations. Pad foundations are suitable for most subsoil types and are usually constructed of reinforced concrete. Strip foundations are used for light structures on stable soil. Raft foundations spread loads over a large area for structures on low bearing soils. Pile foundations transmit loads to deeper soils using columns when suitable shallow foundations are not possible. The document also outlines functions of foundations and materials used, namely concrete composed of cement, aggregates, and water.
General presentation of under-reamed piles. Mainly for diploma engineers, it is really helpful as its objective, dimensions, usage, etc are shown with proper images. It will really helpful for the basic knowledge of under-reamed piles.
This document provides an introduction and overview of pile foundations. It discusses the purpose and functions of pile foundations, including transmitting loads to solid ground and resisting vertical, lateral, and uplift loads. It then classifies piles in multiple ways, such as by load transmission characteristics (end bearing, friction, or a combination), material type (timber, concrete, steel, composite), and installation method (driven or bored). The document outlines each pile type and provides examples to illustrate differences. It aims to extract key points about pile foundations in a clear and student-friendly manner.
Pile foundations are commonly used when soil conditions are unsuitable for surface foundations. Piles transfer structural loads deep into the ground until reaching a competent soil or bedrock layer. Piles can be made of concrete, timber, steel, or a composite material. They are installed by driving, drilling, or jacking and attached to a pile cap. Pile foundations are classified based on material, soil type, and load transfer characteristics. Factors like soil bearing capacity, load intensity, and site conditions determine whether a pile foundation is necessary.
Pile foundations are commonly used when soil conditions require deep foundations, such as with compressible, waterlogged, or deep soils. There are various types of piles classified by function (e.g. end bearing, friction, tension), material (e.g. concrete, timber, steel), and installation method (e.g. driven, cast-in-place). The load carrying capacity of piles can be determined through dynamic formulas, static formulas, load tests, or penetration tests. Factors like pile length, structure characteristics, material availability, loading types, and costs must be considered for proper pile selection.
This document provides an overview of foundations for building construction. It discusses the importance of foundations in distributing building loads to the ground. There are two main types of foundations - shallow foundations and deep foundations. Shallow foundations include spread footings, grillage foundations, raft foundations, stepped foundations, and mat/slab foundations. Deep foundations transfer loads deep into the earth and include drilled caissons, driven piles, and precast concrete piles. Foundation design considers factors like soil type, structural requirements, construction requirements, site conditions, and cost. The document also discusses waterproofing, drainage, and underpinning foundations.
Offshore pile design according to international practiceWeb2Present
In this webinar, industry leading organizations present:
- Learnings from project Borkum West 2, one of German´s most advanced offshore wind projects
- The challenges of the piling design and results of the geotechnical investigation
- Recommendations and observations about potential hazards or obstruction during the foundation installation
Register for free here:
http://www.web2present.com/upcoming-webinars-details.php?id=116
This document appears to be an exam for a Geotechnical Engineering course. It contains 9 questions covering various topics in geotechnical engineering:
1. Short answer questions defining terms like boring methods, fellenous line, retaining walls, ultimate bearing capacity, and test pile.
2. Two sentence descriptions of borelogs, factors of safety for slopes, earth pressure at rest, effect of water table on bearing capacity, and pile classifications.
3. Brief explanations of sample types, Taylor’s Stability Number, Rankine's earth pressure theory assumptions, bearing capacity factors, and negative skin friction.
4. The rest of the questions involve longer form problems, calculations, and discussions covering topics like
This document discusses pile foundations and provides details on:
- Types of pile foundations including driven piles, bored piles, and under-reamed piles
- Analyzing pile capacity using driving formulae, soil mechanics expressions considering shaft resistance, base resistance, and factors like soil type, pile dimensions, and installation method
- Calculating pile capacity in cohesive soils like clay and non-cohesive soils like sand, accounting for soil strength properties and effective stresses
- Considerations for negative skin friction from consolidating or compacting soil layers
This document discusses pile foundations and methods for analyzing pile capacity. It begins with an introduction to pile foundations, including how they transfer structural loads through unstable upper soils. It then discusses different pile types classified by installation method, including large displacement, small displacement, and replacement piles. The document outlines factors that influence pile capacity, such as soil properties and loading conditions. It provides advantages and disadvantages of driven and replacement piles. Finally, it discusses methods for predicting ultimate pile capacity, including total and effective stress analysis, skin friction and end bearing resistance calculations, and pile load testing.
This document provides an overview of pile foundations and their design. It discusses different types of piles including end bearing piles, friction piles, displacement piles, and replacement piles. Modes of pile failure and factors in total and effective stress analysis are examined. Advantages and disadvantages of displacement and replacement piles are compared. Methods for predicting the ultimate capacity of axially loaded single piles in soil are outlined, including considerations for driven piles in clays and bored piles in both granular and clay soils. Load-settlement behavior of friction and end bearing piles is also addressed.
Pile foundations transfer structural loads to deeper, stronger soil strata by bearing loads through end bearing or shaft friction. Piles can be classified as end bearing or friction piles depending on whether they transmit loads primarily through their base or sides. Common pile types include driven piles, which are displaced during installation, and bored piles or replacement piles, which are formed by machine boring. Pile capacity is estimated based on soil properties and load tests may be used to verify estimates.
Pile&Wellfoundation_ManualUpdated as on 20.5.16.pdfDharmPalJangra1
This document provides guidelines for the design and construction of well and pile foundations for railway bridges in India. It covers topics such as the depth of well foundations, shapes and cross-sections of wells, allowable bearing pressures, types of pile foundations, pile spacing, and load carrying capacity of piles. The guidelines are intended to help transfer heavy bridge loads to deep soil strata in a safe and stable manner. Standards are provided for various aspects of well and pile foundation design to suit local soil and construction conditions in India.
Analysis of vertically loaded pile foundationMonojit Mondal
The document discusses pile foundations, including their classification based on material, installation method, and function; load transfer mechanisms; methods for calculating the capacity of single piles and pile groups using static formulas and dynamic formulas per Indian code IS 2911; and concludes that pile foundations provide a common solution for difficult soil conditions and ongoing research continues to improve design.
Pile & pier_foundation_analysis_&_designMohamad Binesh
This document provides an overview of pile and pier foundations, including:
- A classification of shallow vs deep foundations based on embedment depth.
- Examples of historic and modern uses of pile foundations to overcome weak soils.
- A comparison of settlement for different foundation types in deep clay soils, showing piles and pile groups have lower settlement.
- An outline of the process for designing pile foundations according to FHWA guidelines.
- Descriptions of different pile types including timber, steel, concrete, and composite piles.
- Factors to consider when evaluating suitable pile types for a given project.
This document discusses ground improvement using micropiles. It begins with an introduction to micropiles, which were developed in Italy in the 1950s for underpinning historic structures damaged in WWII. It then classifies micropiles based on design criteria (directly loaded vs reinforcing soil) and construction type (gravity grout, pressure grouting, etc.). Advantages include minimal vibration, access in tight spaces, and cost-effectiveness. Applications include foundations, underpinning, slopes, and excavation support. Design considerations and an example are provided based on FHWA guidelines.
This document defines foundations and foundation engineering. It discusses shallow and deep foundations. Shallow foundations include spread, combined, wall/strip, and mat foundations. Deep foundations include piles and piers. It describes factors in foundation design such as ultimate bearing capacity, settlement, and differential settlement. Footing failures by shear, tension, or bearing capacity are addressed. Examples of isolated, combined, and wall footings are provided along with factors in selecting the appropriate foundation type.
This document defines foundations and foundation engineering. It discusses:
1. Foundations transmit structural loads to the soil and come in two types - shallow and deep. Shallow foundations are placed at a shallow depth, typically less than 6m, and include spread footings and strip footings. Deep foundations like piles are embedded much deeper.
2. Foundation engineering involves evaluating soil load capacity and designing foundations to safely transmit loads to the soil while considering economics. It must prevent shear failure, settlement, overturning and sliding.
3. Foundations can fail due to shear, tension or excessive settlement, which depends on factors like soil type and load. Design considers ultimate and allowable bearing capacity as well as allowable settlement.
This document summarizes pile foundations. Pile foundations are used to transfer structural loads through weak soil to stronger soil below. There are different types of piles classified by material (concrete, steel, timber), function (end bearing, friction, anchor), and installation method (driven, bored, driven and cast-in-situ). Formulas are provided to calculate the ultimate bearing capacity of a pile based on factors like soil properties, pile dimensions, and hammer efficiency. Selection of the appropriate pile type depends on project specifics like soil conditions, loading, cost, and availability.
* The group pile consists of 3x4 piles in layered saturated clay
* The piles are square, 14 in. x 14 in.
* Center-to-center spacing is 35 in
* Groundwater table coincides with ground surface
* To calculate consolidation settlement:
1) Use 2:1 method to determine average stress increment in each clay layer
2) Calculate settlement in each layer using consolidation theory
3) Sum settlements in all layers
I do not have enough information provided to calculate the actual settlement values. The process involves breaking down each clay layer, determining average stress increase, and using consolidation theory equations which require soil properties that are not given.
The document discusses pile foundations and their design. It describes different types of piles including end bearing piles, friction piles, displacement piles, and replacement piles. It covers topics such as pile capacity calculation considering end bearing and skin friction, methods of installation, failure modes, total and effective stress analysis, and prediction of pile capacity through pile driving formulas and load testing.
This document provides information about a project involving the construction of pile foundations using the bored cast-in-situ piling method at an English Medium High Madrasha site in Malda. It includes details of the project such as the estimated and tender costs, concrete mix design, pile load testing procedures, and descriptions of the pile classification, boring and concreting process. Reinforcement details and specifications for equipment used in the piling like DMC pipes, tremie pipes, chisel, and casing are also provided.
1. Soil investigations are conducted to obtain information useful for planning, designing and executing construction projects. This includes determining soil properties, groundwater levels, suitable foundation types and depths, bearing capacity, settlements, and lateral earth pressures.
2. Standard penetration tests are used to determine soil properties like relative density and strength. The test involves driving a split spoon sampler into the soil using a hammer and measuring the blow counts. Corrections are made for dilatancy and overburden pressure.
3. Piles can be classified based on material, load transfer method, construction method, use, and soil displacement. Components of a well foundation include the cutting edge, well curb, stining, bottom plug, sand fill
The document provides information on the methodology of construction works summarized in a power point presentation. It discusses specifications for various construction items from two volumes of CPWD Specifications published by CPWD. The power point presentations are useful for students, engineers, and construction departments to understand specifications, standards, and methodology for different construction materials and works. It then provides details on pile work, including terminology, driven cast-in-situ reinforced cement concrete piles, jetting, reinforcement, and concrete.
Presentation for lecture on underwater concrete - TU Delft: MSc Geotechnical ...Ruud Arkesteijn
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2. UCFs are commonly used in the Netherlands for sub-surface construction in soft soils below the groundwater level, serving functions like retaining water, distributing horizontal and vertical forces.
3. Design rules are provided in CUR77, which was revised in 2014 to comply with Eurocodes. The rules cover modeling, dimensioning, and detailing of unreinforced UCFs.
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This document discusses Indian standards related to piles and provides information on various types of piles. It covers piles categorized by standards, material, installation method, load carrying characteristics, and testing methods. The key points are:
- It outlines Indian standards for different types of piles including concrete, timber, and pile testing.
- Piles are classified by material as concrete, steel, timber, or composite piles made of two materials.
- Installation methods include displacement piles driven into soil and replacement piles where soil is removed.
- Piles carry loads through end bearing, friction along the pile, or a combination depending on the soil conditions.
- Pile load tests directly measure a pile's capacity and
1) Two approaches are used to determine the safe bearing pressure of soil: allowable bearing pressure based on shear failure criteria, and safe bearing pressure based on settlement criteria.
2) Plate load tests can be used to estimate the safe bearing pressure that results in a given permissible settlement. Tests are conducted with plates of different sizes and the load-settlement data is used to calculate settlement of prototype foundations using empirical equations.
3) Housel's method involves conducting two plate load tests and solving equations involving load, plate area and perimeter to determine constants, which are then used to calculate load and size of a prototype foundation that results in the permissible settlement.
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2. 1,0 INTRODUCTION
Piles are used where a structure cannot be supported satisfactorily on a shallow
foundation.
A single pile can be defined as "a long slender, structural member used to
transmit loads applied at its top to the ground at lower levels".
Examples of where piled foundations may provide a solution are:
. Where a soil layer of adequate bearing capacity lies too deep for the
economic use of conventional footings.
. Where the soil layer(s) immediately underlying a structure are soft
or poorly compacted.
. Where the soil layer(s) immediately underlying a structure are
moderately or highly variable in nature.
. On sites where the soil strata, and in some cases the ground
surface are steeply inclined.
. On river or shoreline sites where tidal or wave action or scouring
may vary the amount of material near the surface.
. For structures transmitting very high concentrated loads.
. For structures transmitting significant horizontal or inclined loads.
. For structures which structurally or functionally may be sensitive to
d iffe rentia I settlement.
For more detailed treatment of piling methods. pile types and design, refer to
the books by Tomlinson (1987), Poulos (1980), Fleming (1985) and Whitaker
( 1e70).
A pile carries the applied load via:
1. A shear stress mobilised (developed) on the surface ofthe shaft of
the pile. This is called
skin friction in sands and
adhesion in clays.
2. Bearing capacity at the base of the pile, called end bearing.
From the point of view of both design and construction, piles are classified into
two types:
a) Driven or displacement piles - which are usually
preformed before being driven, jacked. screwed or
hammered into the ground,
b) Bored or replacement piles - which first require a hole
to be bored into which the pile is then formed, usually of
reinforced concrete.
Pile Foundations v1 .00 Oct2010
3. Piles may also be classified according to how they achieve their load carrying
capacity;
end bearing piles or
friction piles.
In the majority of cases however, the load carrying capacity is dependent on
both the end bearing and shaft friction.
NOTE:Pile design must be accompanied by in situ load testing. Eurocode 7
emphasises that pile design must be based on static load tests or on
calculations that have been validated by these tests.
t=Tr
llsolt ll
*ril II
II
I--+J-----roLli I
End
bearing
tl+
11--fl-lrfiH[{
.,,,,H ,li I
ilI-
Floating
or 1l'iction
Tvpes of pile foundations
1.1 Choice of pile type
1.1.1 Driven or Displacement oiles
a) Preformed piles:
. Advantages: -
. Disadvantages: -
+
Undt'r-
re amcd
Upiili Frec-strnding
may be inspected for quality and soundness
before driving
not liable to squeezing or necking
construction not affected by ground water
can be left protruding above G.L. (useful in
marine structures)
can withstand high bending and tensile
stresses
-can be driven in long lengths
unjointed types cannot easily be varied in
length
may break during driving
uneconomic if the design is governed by
driving stresses rather than working stresses
noise and vibration during driving
displacement of soil may affect adjacent
structu res
cannot be driven in situations of low head
room
Pile Foundations vl .00 Oct2010
4. b) Cast in place piles
. Advantages: - length can easily be adjusted
- ground water can be excluded by driving with
a closed end
- enlarged base possible
- design governed by working conditions
- noise and vibration reduced by internal drop
hammer
. Disadvantages: - necking is possible where temporary tubes are
used
- concrete cannot be inspected after installation
- length may be limited if tubes are to be
extracted
- displacement may damage adjacent
structu res
- noise and vibration may be unacceptable
1.1.2 Bored or replacement oiles
a) Cast in place piles:
. Advantages: - length can be varied
- removed soil can be compared with design
data
- penetration tests can be carried out in
boreholes
- very large bases can be formed in favourable
ground
- drilling tools can break up boulders and other
obstructions
- pile is designed to working stresses
- very long lengths possible
- little noise and vibration during construction
- no ground heave
. Disadvantages: - piles liable to squeezing and necking in soft
soils
- special techniques required for concreting in
water bearing ground
- concrete cannot be inspected after installation
- enlarged bases cannot be formed in
collapseable soil
- cannot be easily extended above ground
- boring may cause instability and settlement of
adjacent structures
2.O ANALYSIS OF PILES
Analysis of piles is quite complex and there are two main approaches:
1. Estimate the carrying capacity from driving formulae and load tests
(only suitable for sands/gravels or stiff clay)
2, Calculate the carrying capacity from soil mechanics expressions.
4-
Pile Foundations v1 .00 Oct2010
5. 2.O.1 Driving Formulae
There are many different expressions - all try to relate the energy needed to
drive the pile to the penetration of the pile (for which there is no theoretical
justification).
e.g. Hiley Formula;
R,= Whn
s+c/2
Where;
R, = ultimate driving resistance
W = weight of hammer
h = fall of hammer
n = efficiency of blow, found from graph
s = set or penetration/blow
c = total temporary compression of pile
Driving formulae take no account of soil type or conditions and are therefore
oenerallv disaooroved of bv foundation engineers.
The only sure way is to drive some test piles and then carry out load tests -
thereby finding the carrying capacity - time and cost are big disadvantages.
2.O.2 Analysis using soil mechanics
Load capacitv of single piles
There are two forms of resistance provide by the pile to the applied vertical
loads:
. shaft resistance
. base resistance
At failure the ultimate values of both these resistances are mobilised to give:
and
Qu=Qs+Qu
ultimate pile capacity
ultimate shaft resistance
ultimate base resistance
qb x Ab = base bearing capacity x area of base
surface area of shaft in contact with the soil
x shear strength of the soil
c6ndL (clays) ; where ca = adhesion
fsndL (sands) ; where fs = skin friction
d = diameter of pile
L = length of pile in contact with the soil
-5-
Pile Foundalions v1 .00 Oct2010
where :
Qu=
Qs=
Qu=
Qo=
Q.=
Q.=
Qs=
where
6. Piles usually penetrate several different soil types, each providing different shaft
resistances and the total shaft resistance is the summation of the individual
values.
The weight of the pile is usually ignored in the above equations, since it is
approximately equal to the weight of soil removed or displaced.
2.t Piles in cohesive soil (claylsilt ; 0 = O")
Ultimate pile capacity, Q, = Qo + Qs
QU
2.1.1 Bored oiles
Base resistance, Qo (kN):
Where
Shaft resistance, Q.(kN) :
Where
Qb
I
I
= qb Ab
= cu N6 A6
= base bearing capacity = cu Nc
= cross sectional area of pile base (mz)
= undrained shear strength at base of pile
= bearins capac*v factor =
?:9J'fti3ji.il}?]"",1,
=CaAs
= adhesion
= ad,
= adhesion factor
[usually taken as 0.45, but may vary from
1.0 for soft clays to
0.3 for overconsolidated claysl
= average undrained shear strength over length
of pile, L
= diameter of pile
= length of pile in contact with soil stratum
-6-
Pile Foundations v'l .00 Oct2010
Qr
qb
At
Cu
Nc
Qt
C6
Cu
d
L
7. Class example 1
A bored pile, 750mm diameter and 12.0m long, is to be installed on a
site where two layers of clay exist;
Upper firm clay; 8.0m thick;
undrained shear strength = 50.0 kN/m'z.
Lower stiff clay; 12.0m thick;
undrained shear strength = 120.0kN/m2.
Determine the working load the pile could support assuming the
following:
i) o = O.7 for firm clay and 0.5 for stiff clay I N. = 9
ii) Factors of safety of 1.5 and 3.0 are applied to the shaft
load and base load respectively
iii) The top 1.0m of the firm clay is ignored due to
clay/concrete shrinkaqe. [921 kN]
Class example 2
For the ground conditions and assumptions described in Example 1,
determine the length of pile required to support a working load of
1200 kN. 114.96m, say 15mI
2.1.2 Under-reamed oiles
Often used in cohesive soils to increase
the base area of the pile, thereby
increasing the base resistance.
For under-reamed piles the adhesion
should be ignored over the:
a) height of the under-ream.
b) main shaft of the pile up to 2 shaft
diameters above the top of the
under-ream and
c) top 1m of the pile (zone of seasonal
shrinkage).
Und et rea.tt
A
lq,
Class example 3
A large under-reamed bored pile is to be installed in stiff clay with
undrained shear strength of 125kN/m2. The main shaft of the pile is
1.5m diameter and the base of the under ream is 4.5m diameter with a
height of 3.0m and the total length of the pile from the ground level to
the base of the under ream is 27m.
Determine the working load of the pile in MN, assuming the following:
a)cr=0.3 i N.=9
b) A factor of safety of 3.0 should be applied to the base load
but full mobilisation of shaft adhesion can be assumed.
t9.498MNl
-7-
Pile Foundations v1 .00 Oct2010
8. 2.1.3 Driven piles
Base resistance Qb:
Qn = cu N6 A6 (as above)
Shaft resistance Qs:
a' = cr-cu A.
=c.6zrdL
where;
cr = adhesion factor dependent on depth of
penetration and type of overburden, value
found from graph (see next page)
6 = average undrained shear strength over pile
length L
d = diameter of pile
L = length of pile in contact with soil stratum
Class example 4
A closed end pipe pile, 600mm diameter is driven to a depth of 15.0m
into a stiff clay. The undrained shear strength of the clay is 140.OkN/m'z.
Assume c = 0,43
Determine the working load (kN) the pile could support with an overall
factor of safety of 2.5.
t778.O kNl
-8-
Pile Foundations v1 .00 Oct2010
9. U
o
o
a
=c
E
it
1.00
0.75
0.50
sands or
y gravels
stiff clay
50 100 150 200
Undrained shear strength ofclay (kNim'?)
Adhesion factors for short piles(L<1Od) driven into stiff clay
50 100 150 100 250
Urrtlrrinctl shcrr strenclh of clry {l,N/rrr:,
Adhesion factors for long piles(L>20 to 4Od) driven into stiff clay
(Tomlinson, 1987)
250
.2s l
,J
0
t.00
0.75
0.50
0.25
0
0
sands or sandy gravels
I
ar
overburden
- soft clav_--..-.-..-_......-.-
srnds (1. = l0r/)
--------....-.----.-.
*
sofr clay ,,t . 20d)
:--- srnds 1/. = J0r/)
no 0'elil;:-; -:-
-9-
Pile Foundations v1.00 Oct2010
10. 2.2 Piles in non-cohesive soil (sand/gravel ; c = O)
Ultimate pile capacity, Qu = Qo + Qs
2.2.1 Driven piles
Base resistance Qb:
Qo=Qo.Ao
Where;
1000
Au = cross sectional area of pile base
qb = base bearing capacity = Nq ov'
Nq = bearing capacity factor, see chart
below
6v' = vertical effective stress at the base
of the pile
Qr = Nq ov' Ao
Nq
100
l0 L-
t5 30 35 40
Angle of intemal friction @ '
(From Berezantsev et al 1961)
QU
T
45
-10-
Pile Foundations v1 .00 Oct2010
11. The internal angle of friction {', before the installation of the pile, is not easy to
determine since disturbance will occur during piling. The $' value used is
obtained from correlations with the SPT'N'values as shown below:
StaDdard penetrarion resistance 'N' (blows/300 mm)
42
; "1{J
.9
5
518
a
i -16
.=
. l-l
:
-z 1
.tt)
7
d'relared to Standard penetr.tion aesistance ^N'
(Peck, Hanson and Thombum. 1974)
Critical depth, zc
As the depth of pile penetration increases, the veftical effective stress increases
and therefore the end bearing should increase. Field stress have shown,
however, that end bearing does not increase continually with depth. A possible
explanation is that as O' increases the bearing capacity factor decreases.
This has lead to the concept of critical depth zc , below which shaft and base
resistance are considered to be constant (i.e. the values for z. and below).
The value of zc is determined from charts relating depth to O' - these are
somewhat tentative,
Shaft resista nce Qs:
Qr = f. A,
where
fs = skin friction on pile surface
= Ks tan 6 -ov'
A, = area of pile in contact with the soil
= n d L (cylindrical pile)
and
Ks = coefncient of horizontal effective stress
E = angle of friction between pile sudace and soil
-av' = average effective vertical stress
a. = K. tan 66v'n d L
The method of installation affects the values of K, and 6 and they are usually
presented as one factor as shown below;
..0 r0 20 30 J0 50 60 70
-11-
Pile Foundations v1 .00 Oct2010
12. 1.6
Driven pilcs
/
Jacked piles
Bored piles
1.2
-o
! 0.8
k
0..1
o:b :1-s "10
Initial angle of internal lriction @',
Class example 5
A 10.5m long concrete pile, 400mm square, is to be driven into a thick
deposit of medium dense sand, with an SPT'N'value of 25 and a bulk
unit weight of 20.0 kN/m2. The water table lies at 2.5m below ground
level,
Estimate the working load this length of pile will support assuming an
overall factor of safety of 2.5 and the sand has a saturated unit weight
of 20.0kN/m3
[949.2kN]
2.2.2 Bored piles
Boring holes in sands loosens an annulus of soil around the hole and reduces
horizontal stresses, Consequently bored piles in dense sands can be expected to
have low bearing capacity. Casting concrete in situ will produce rough sufaces
but this effect is diminished by the loosening of the sand.
Poulus(1980) suggests analysing as if for a driven pile but using reduced values
of ou',
Meyerhof (1976) suggests designing as if for a driven pile, but using one third of
the base resistance and one half of the shaft resistance.
-12-
Pile Foundations v1 .00 Oct2010
13. 3.O NEGATIVE SKIN FRICTION
This term refers to the action (friction or adhesion) of soil layer/s acting with the
applied loading i.e. against the pile resistance. It is usually caused by either;
. Clay soil undergoing consolidation settlement or
. Fill material compacting over time
Negative skin friction is caused by a dragging down effect by the consolidating /
compacting layer plus any overlying strata, see diagrams below. Conseguently
the values of friction or adhesion for the consolidating soil must be added to the
applied load. Treat skin friction values as load on the pile and are !q! factored.
(recently
placed)
Compresses
under own
weight.
Class example 6
A 300m square concrete driven pile driven 12.0m into a layered soils as
follows;
Fill (recent) 2.5m thick (y = 26.0 kN/m3 4'= 371
Medium SAND 3.0m thick 0 = l7.O kN/mi; N = 18)
Soft CLAY 2.0m thick (y."t = 22.0 kN/m3)
Compact SAND 9.0m thick (y.u1 = 22.0 kN/m3; N = 33)
The strength of the soft clay increases linearly from 18.0 kN/m2 at 5.5m
below ground level to 36.0 kN/m2 at a depth of 7.5m. A water table is
present at a constant depth of 5.5m below ground level.
Determine the safe working load of this pile by adopting factors of safety
of 1.5 and 2.5 for the shaft and end bearing resistance respectively.
[12s6.3 kNl
4.O WORKING LOAD OF PILES
In order to determine the working or safe load that a pile can carry, it is
necessary to apply factors of safety in order to limit the settlement to a
permissible value.
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14. Different authors apply various factors of safety to different pile conditions.
However the following values are generally accepted.
For piles up to 600mm diameter
An overall factor of safety of 2.5 should be adopted, to give a settlement which
is unlikely to exceed 10mm.
. ultimate load
worklnq loao = - *2.5
For piles larger than 600mm diameter
It is necessary to apply partial factors of safety to the ultimate base and shaft
resistance values
For London Clay, Burland (1966) suggests that providing an overall factor of
safety of 2 is obtained, partial factors on the shaft and base of 1 and 3
respectively should be applied, so that the working load, Q" is the smal/er of :
^ a-t-a' oR q" = * * -Fva- 2
The first expression governs the design of straight shafted piles and the second
governs the design of large under reamed piles.
For soils other than London Clay, e.g. Glacial Till (boulder clay), where there is
uncertainty about the effects of installation, ground conditions etc, higher factors
of safety should be used so that the working load Q" is smaller of :
.-, _ Q' + Qr
^o .,,, - -Qr
_, Qu
va: 2.5 -,^ v" - t.5 - 3.5
Class example 7
Determine the length of a pile, 1200mm diameter, to support a working
load of 4500kN in a thick deposit of clay with an undrained shear
strength increasing linearly with depth from 55.0kN/m2 at ground level
and at 5,0kN/m2 per metre depth. Assume;
a. the top 1.0m of the pile does not support load due to
clay/concrete shrinkage
b. an adhesion factor, c = 0.5; N. = 9.0
c. factors of safety of 1.5 and 3.0 on the shaft load and
base load respectively.
[29.5m, sav 3OmI
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15. 5.O SUMMARY
Types of pile: Driven or displacement piles Bored or replacement piles
Piles in cohesive soil (clay/sil$ O = Oo)
BORED PILES
Base resistance;
Qr = cuNgA6
where,
Au = cross sectional area of pile base
cu = undrained shear strength at the base of the pile
Nc = bearing capacity factor
= 9.0 for intact clays or
= 6.75 for fissured clays
Shaft resistance;
Qs = u.u As
wh e re,
o = adhesion factor, usually taken as 0.45, but
may vary from; 1.0 for soft clays to
0.3 for overconsolidated clays
c, = average undrained shear strength over length of
p ile
As = surface area of pile in contact with soil stratum
DRIVEN PiLES
Base resistance;
Qu = Cg Ns A6 as above
Shaft resistance;
a. = oGA
where,
o = adhesion factor dependent on depth of
penetration and type of overburden, value
found from graph
c, = average undrained shear strength over pile
length
A" = surface area of pile in contact with soil
stratum
Under-reamed piles
Increase of the base area of the pile, thereby increasing the base resistance.
The adhesion should be ignored for a distance of two diameters above the top of the
under ream.
Piles in non-cohesive soil (sand/gravel; c = O)
DRIVEN PILES
Base resistance;
q = Nq o"'fu
where,
fu = cross sectional area of pile base
Nq = bearing capacity factor, found from graph
ou' = vertical effective stress at the base of the pile
Shaft resistance;
a, = K,tan6 d"'As
where,
K,tan6 = installation Factor from graph
6u' = average effective vertical stress
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16. As = surface area of pile in contact with the soil
BORED PILES
Boring holes in sands loosens an annulus of soil around the borehole, hence low bearing
capacity.
Analyse as if for a driven pile but using reduced values of w', or use 1/3 of the base
resistance and 1/2 of the shaft resistance.
Negative skin friction
The action of fiction or adhesion acts WITH the applied loading i.e. against the pile
resistance. Consequently the values of friction or adhesion for the consolidating soil
must be added to the applied load. Do NOT factor down skin friction values.
Working load of piles
Apply factors of safety in order to limit the settlement to a permissible value.
For piles =<600mm diameter
Use an overall F of S of to give a settlement of <10mm.
For oiles >600mm diameter
Apply partial factors of safety to the base resistance and the shaft resistance.
For London Clay, an overall F of S of 2.0 is obtained, with partial factors on the shaft
and base of 1 and 3 respectively, so that the working load, Qa is the smaller of:
.., - Q.+Qr t
- Qo
a"=--:z- OR Q,=fr ,
The first expression governs the design of straight shafted piles and the second governs
the design of large under reamed piles.
For soils other than London Clay, where there is uncertainty about the effects of
installation, ground conditions etc, higher factors of safety should be used Qa is the
smaller of:
e"=i*k oR a"=+.+Note:
For negative skin friction, the above factors of safety are NOT applied to the
element of load acting against the pile resistance,
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Pile Foundations v1.00 Oct2010
17. REFERENCES
Berezantsev et al (1961) Load bearing capacity and deformation of piled
foundations Proc. 5th Int Conf Soil Mechanics and Foundation Engineering,
Paris, vol.2 pp.lI - t2
Burland, J B et al (L966) The behaviour and design of large-diameter bored piles
in stiff clay Proceedings, Symposium on large bored piles ICE, London
Fleming, W G K et al (1985) Piling engineering Surrey University Press /
Halstead Press
Meyerhof, G G (1976) Bearing capacity and settlement of pile foundations,
Proceedings, American Society of Civil Engineers 102(GT3), pp 195-228
Poulos H G and Davis. E H (1980) Pile foundation analysis and design John Wiley
& Sons, New York.
Tomlinson, M I (1987) Pile design and construction practice 3rd Ed, Viewpoint
Publications, Palladian Publications Ltd.
Whitaker, T (1970) The design of piled foundations Oxford : Pergamon
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