This document discusses prestressed concrete and provides details on:
- The definition and principle of prestressing concrete by applying compression prior to external loads
- Common prestressing methods like hydraulic, mechanical, electrical, and chemical prestressing
- Tests conducted on prestressed concrete components like post-tensioned splices and cast-in-place splices
- Advantages of prestressed concrete like reduced materials and increased strength
- Applications in bridges, buildings, water tanks, and more
- A case study on widening the Harrods Creek Arch Bridge using prestressed concrete
Prestressed concrete structures and its applications By Mukesh Singh GhuraiyaMukesh Singh Ghuraiya
1. What is Prestressed??
2. Principle of Prestressed
3. Method of prestressing
4. Prestressed concrete structures
5. Advantages/application of Prestressed concrete
6. Disadvantages of Prestressed concrete
7. Comparison of RCC and Prestressed Concrete Flat Slabs
It is the presentation based on precast concrete construction which includes each and every point and scope which may be useful to civil engineering students
Prestressed concrete is a structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading.
A presentation that explains the various systems and techniques of employing steel and concrete to support long span structures. The range varies from conventional beams, to trusses and portal frames.
Prestressed concrete structures and its applications By Mukesh Singh GhuraiyaMukesh Singh Ghuraiya
1. What is Prestressed??
2. Principle of Prestressed
3. Method of prestressing
4. Prestressed concrete structures
5. Advantages/application of Prestressed concrete
6. Disadvantages of Prestressed concrete
7. Comparison of RCC and Prestressed Concrete Flat Slabs
It is the presentation based on precast concrete construction which includes each and every point and scope which may be useful to civil engineering students
Prestressed concrete is a structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading.
A presentation that explains the various systems and techniques of employing steel and concrete to support long span structures. The range varies from conventional beams, to trusses and portal frames.
Tall Structures
Usually structure or building having height more than 80m is considered as a tall structure.
Generally tall structure may be defined as one that because of its height it is affected by lateral.
Classification: 1. Multi storeyedresidential building.
2. Multi storeyedcommercial building.
3. Tall chimneys.
4. Transmission Towers
5. Cooling towers
Prestressed Concrete
•Prestressis defined as a method of applying pre-compression to control the stresses resulting due to external loads below the neutral axis of the beam tension developed due to external load which is more than the permissible limits of the plain concrete.
Demolition
•The action or process of destroying(demolishing)the building or other structures.
•In congested area, in particular, the quality of demolition technique becomes an essential element which determines the success of revitalization of city.
•In addition to efficiency in demolition, strategies must be adopted to avoid noise, vibration and dust which affect the surrounding environment and there must be efficient disposal of waste products
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
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It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
2. CONTENTS
INTRODUCTION
DEFINITION OF PRESTRESS
PRINCIPLE OF PRE-STRESSING
METHOD OF PRESTRESSING
GIRDER DESIGN
WORKING OF PRESTRESSED CONCRETE
DIFFERENCE B/W ORDINARY AND PRESTRESSED CONCRETE
TYPES OF PRESTRESSED CONCRETE
TEST ON PRESTRESSED CONCRETE
ADVANTAGES AND DISADVANTAGES OF PRESTRESSED CONCRETE
APPLICATION
CASE STUDY
CONCLUSION
3. INTRODUCTION
Prestressed concrete is a method for overcoming concrete's natural
weakness in tension.
In 1904, Freyssinet attempted to introduce permanent acting forces .
To resist elastic forces under loads and was named “Pre Stressing”.
It can be used to produce beams , floors , bridges with a longer span
than is practical with ordinary reinforced concrete.
4. DEFINITION OF PRESTRESS
• Prestress is defined as a method of applying pre-
compression to control the stresses resulting due to
external loads below the neutral axis of the beam
tension developed due to external load which is more
than the permissible limits of the plain concrete.
5. PRINCIPLE OF PRE-STRESSING
• Pre-stressing is a method in which compression force is
applied to the reinforced concrete section.
• Pre-stressing tendons (generally of high tensile steel cable or
rods) are used to provide a clamping load which produces a
compressive stress that balances the tensile stress that the
concrete compression member would otherwise experience
due to a bending load.
6. METHODs OF PRESTRESSING
This classification is based on the method by which the prestressing
force is generated.
Hydraulic Prestressing
Mechanical Prestressing
Electrical Prestressing
Chemical Prestressing
7. GIRDER DESIGN
• For transportation and handling purposes of the pier segments of both tx70 and
Texas u54 girder bridges.
• Diameter are provided in the bottom flange of the pier segments.
• Various corrosion protection systems are available for these 106 thread bars, none
of which bond with the structure.
• Once the pier segment is erected on site, it behaves as a cantilever.
• The preliminary designs for tx70 and Texas u54 girder bridges assumed shored
construction.
• From the preliminary designs, it was noted that the span lengths of 280 ft and 240 ft
for the continuous prestressed concrete bridges using the standard tx70 and texas
u54 girders, respectively are achieved using shoring towers (shored construction)
and by making the girder sections work up to their limits.
8. WORKING OF PRESTRESSED
CONCRETE Pre-stressed concrete refers to a procedure whereby
tensile rods are put in place first and tightened,
followed by concrete pouring.
Compression can be applied after pouring concrete
using bonds. They are tightened once the concrete is
dry
Main disadvantage is that a cable can burst out of the
slab, if the anchoring system fails.
9. DIFFERENCE B/W ORDINARY AND
PRESTRESSED CONCRETE
• Even without a load, the
ordinary concrete beam
must carry its own weight.
• An upward force is created
which in effect relieves the
beam of having to carry its
own weight.
10. TYPES OF PRESTRESSED
CONCRETE
• There are two types of prestressed concrete.
• They are
Pre- tensioned concrete
Post tensioned concrete
11. PRE-TENSIONED CONCRETE Pre-tensioned concrete is cast around
already tensioned tendons.
This method produces a good bond
between the tendon and concrete, which
both protects the tendon from corrosion and
allows for direct transfer of tension.
The cured concrete adheres and bonds to
the bars and when the tension is released it
is transferred to the concrete as
compression by static friction.
13. POST TENSIONED CONCRETE
Post tensioning is a technique for reinforcing concrete.
Post-tensioning tendons, which are prestressing steel cables inside plastic ducts
or sleeves, are positioned in the forms before the concrete is placed.
Afterwards, once the concrete has gained strength but before the service loads
are applied, the cables are pulled tight, or tensioned, and anchored against the
outer edges of the concrete.
They are classified into two types,
Bonded post tensioned concrete
Unbonded post tensioned concrete
15. BONDED POST-TENSIONED
CONCRETE
• Bonded post-tensioned concrete is the descriptive term for a
method of applying compression after pouring concrete and
the curing process (in situ).
• The concrete is cast around a plastic, steel or aluminum
curved duct, to follow the area where otherwise tension would
occur in the concrete element.
16. UNBONDED POST-TENSIONED
CONCRETE
• Unbounded post-tensioned concrete differs from bonded post-
tensioning by providing each individual cable permanent
freedom of movement relative to the concrete.
• To achieve this, each individual tendon is coated with a grease
(generally lithium based) and covered by a plastic sheathing
formed in an extrusion process.
18. POST- TENSIONED SPLICE
The specimen was loaded through a hydraulic jack at the
centerline of the span. The jack reacted against a steel
test frame bolted to the foundation. Elastomeric bearing
pads were used at the end bearings and between the jack
and the slab. The jack had a capacity of 400 kips, while
the test frame was rated at about 200 kips. The jack had
been pre-calibrated for correspondence between gage
pressure and applied load.
23. RESULT
MEMBER 6”*12” cylinder compressive strengths
1 day 7 days 28 days
Beam
slab
3790 psi
4180 psi
4990 psi
5060 psi
5380 psi
5440 psi
24. CAST-IN-PLACE SPLICE
The splice contemplated in the present application
consists of cast-in place concrete section of perhaps 4
feet in length, reinforced with mild steel bars
projecting from each precast element. Supplemental
stirrups are also used in the splice. (Possible
variations would include post-tensioning the cast-in-
place portion, but this will not be considered herein)
31. ADVANTAGES
Take full advantages of high strength concrete and high
strength steel
Need less materials
Smaller and lighter structure
No cracks
Use the entire section to resist the load
Better corrosion resistance
Very effective for deflection control
Better shear resistance
32. DISADVANTAGES OF
PRESTRESSED CONCRETE
• The availability of experienced builders is scanty.
• Initial equipment cost is very high.
• Availability of experienced engineers is scanty.
• Prestressed sections are brittle
• Prestressed concrete sections are less fire
resistant.
33. APPLICATION
• Bridges
• Slabs in buildings
• Water tank
• Concrete pile
• Thin shell structures
• Offshore platform
• Nuclear power plant
• Repair and rehabilitations
34. CASE STUDY
HARRODS CREEK ARCH BRIDGE WIDENING
• Completion Date: August, 2010
• Cost: $34,00,000
• Designer: Stantec Consulting
• Client/Owner: Louisville Metro Public Works
• Contracter MAC Construction & Excavating, New Albany, Indiana.
• Located on River Road over Harrods Creek near Prospect, Kentucky, 10 miles
northeast of Louisville
• River Road is a Kentucky Scenic Byway and the bridge is located within the
Harrods Creek Historic District.
36. CONCLUSION
• Thus, pre-stressed concrete increases the quality, strength,
span of the structure.
• Since it is cost effective, it is used widely on recent days.