Eabs intro & Siesmic Terminologies UBC-1991

Three Dimensional
Static and
Dynamic Analysis
and Design of
Buildings
Three Dimensional
Static and
Dynamic Analysis
and Design of
Buildings
Structural Designing Course
Build‐Tech Consultants Pvt .Ltd
INTRODUCTION TO ETABS & SEISMIC
TERMINOLOGIES
INSTRUCTOR:
M.OMAIR JAMIL

ETABS SOFTWARE
• ETABS is a powerful program that can greatly enhance
an engineer's analysis and design capabilities for
structures. Part of that power lies in an array of options
and features. The other part lies in how simple it is to
use.
• ETABS is a finite element base software that is software
divide every structural element in finite pieces and every
piece has two nodes.
• In analysis every node has a reaction which
superimposes on each other for a final result.
• In this way results obtained from this software is very
precise & ACCURATE.

Key Features
• Fully integrated interface within
Windows XP/WIN 7/WIN 8
• Optimized for modeling of
multistory buildings
• 3D perspective plan, elevation,
developed elevation, and custom
views
• 3D model generation using plans
and elevations
• CAD drawing/editing for fast,
intuitive framing layout
Key
Features

Key Features
• Extensive Analysis Capabilities
– Linear Static Analysis
– Linear Dynamic Analysis
– Static and Dynamic P‐Delta Analysis
– Static Non‐Linear Analysis
– Dynamic Non‐Linear Analysis
– Pushover Analysis
– Multiple Response Spectrum Analysis
– Multiple Time History Analysis
Key
Features

Key Features
• Fast generation of
model using the
concept of similar
stories
• Automated templates
for typical structures
• Easy editing with
move, merge, mirror
and replicate
Key
Features

Key Features
• Multiple views in 3D perspective with zooming and
snapping
• Onscreen assignment of properties, loading and supports
• Powerful grouping, selection and Display options
• Cut, copy and paste options
Key
Features

Key Features
• Unlimited levels of undo
and redo
• Cut/Paste geometry to
and from spreadsheets
• Import and export of .DXF
file for model geometry
• Detailed context‐sensitive
online help
• Analysis integrated with
post‐processing and
design
Key
Features

Realistic Modeling
Interactive
Modeling

Powerful Viewing Options
Interactive
Modeling

Flexible Grid Systems
• Convenient dividing and
meshing of design
objects
• Multiple simultaneous
rectangular and
cylindrical grid systems
• Accurate dimensioning
with guidelines and
snapping
• Quick‐draw options to
create objects with one
mouse click
Interactive
Modeling

Parametric Templates
• Automated model generation for typical
structures using powerful templates
– Steel Deck
– Flat Slab
– Two‐way Slab
– Waffle Slab
– Ribbed Slab
Interactive
Modeling

“Similar “ Story Concept
• Time saving
Story
definitions
using the
concept of
similar Stories
• Common
labeling of
Objects
between similar
Stories
Interactive
Modeling

Object Based Modeling
• Area objects for
– Walls, Slabs/Decks,
Opening
• Line objects for
– Columns, Beams, Braces,
Links, Springs, Mass, Loads
• Point objects for
– Supports, Springs, Mass,
Loads
Interactive
Modeling

Rigid Diaphragm Concept
• Define Rigid
Diaphragms to
effectively
model floor
slabs and to
constrain
deformations
Interactive
Modeling

Extensive Section Database
• Built‐in
database of
steel
sections
Interactive
Modeling

Powerful Section Designer
• Graphical Section Designer
for defining custom
sections
Interactive
Modeling

Building Loads
• No limit on
number of
independent load
cases
• Gravity loads
specified as point,
line or area loads
• Wind and Seismic
Load Generator for
several codes
Interactive
Modeling

Building Loads
• Automatic wind
load generation
– UBC, BOCA, ASCE,
NBCC
Interactive
Modeling

Building Loads
• Automatic Seismic
Load Generation
– UBC, BOCA, NBCC
Interactive
Modeling

Building Loads
• Built‐in response
spectrum and
time history input
• User‐defined
response
spectrum
functions
• User defined time
history functions
Interactive
Modeling

Powerful Object Based Elements
• Area objects
– Walls
– Slabs/Decks
– Opening
• Lines objects
• Columns
• Beams
• Braces
• Links
• Non‐linear Link
• Lines objects
• Columns
• Beams
• Braces
• Links
• Non‐linear Link
• Point objects
– Supports
– Springs
– Mass
– Loads
• Point objects
– Supports
– Springs
– Mass
– Loads
Modeling
Elements

Wall, Slab, Deck Elements
• Shell, plate or
membrane action
• General quadrilateral
or triangular element
• Six degree of freedom
per joint
• Uniform load in any
direction
• Temperature and
thermal‐gradient
loading
Modeling
Elements

DIFFERENCE BETWEEN
MEMBRANE,SHELL AND PLATE

Joint Element
• For modeling of
Support
• Coupled or uncoupled
grounded springs
• Force loads
• Ground‐displacement
loads
• Inclined Supports
Modeling
Elements

0][ 2
 MK
)cos()()()( tptrtuMtKu 


Main Analysis Options
• Linear Static Analysis
• Linear Dynamic Analysis
• Static and Dynamic P‐
Delta Analysis
• Static Non‐Linear
Analysis
Analysis
Options

Special Analysis Options
• Automatic transfer
of loads on
decks/slabs to
beams and walls
• Automatic
meshing of frame
members into
analysis elements
• Automatic
meshing of
decks/slabs for
flexible diaphragm
analysis
Analysis
Options

Dynamic Analysis Options
• Static and dynamic
response
combinations by ABS
or SRSS method
• Eigen and load‐
dependent Ritz vector
determination
• Model combination by
SRSS, CQC or GMC
(Gupta) method
• Combination of three
direction by ABS or
SRSS method
Analysis
Options

Analysis Results
• Deformed and
Un‐deformed
geometry in 3D
perspective
• Animation of
deformed
shapes
Analysis
Results

Analysis Results
• Bending‐Moment
and Shear‐Force
diagrams for Frames
• Instantaneous on‐
screen results
output with right‐
button click on
element
• Integrated‐force
diagrams for Wall
Piers and Spandrels
Analysis
Results

Analysis Results
• Loading diagrams
• Stress contours
for shells
• Interactive
Section‐force
results using
Groups
Analysis
Results

Fully Integrated Element Design
• Design of Steel Beams, and Columns
• Design of Concrete Beams and Columns
• Design of Composite Beams
• Design of Concrete Shear Walls
Member Design

Concrete Frame Design
Member Design

• Fully integrated concrete
frame design
• ACI, UBC, Canadian and Euro
codes
• Design for static and dynamic
loads
• Seismic design of
intermediate/ special
moment‐resisting frames
• Seismic design of beam/
column joints
• Seismic check for strong‐
column/ weak‐beam design
Member Design

• Graphical Section Designer
for concrete rebar location
• Biaxial‐moment/ axial‐load
interaction diagrams
• Graphical display of
reinforcement and stress
ratios
• Interactive design and
review
• Summary and detail reports
including database formats
Member Design

Shear Wall Design
Member Design

Concrete Shear Wall Design
• Fully integrated wall pier and
spandrel design
• ACI, UBC and Canadian
Codes
• Design for static and
dynamic loads
• Automatic integration of
forces for piers and spandrel
Member Design

The seismic zone factor Z, given in UBC table-16-
1, is the Code estimate of the applicable site
dependent effective peak ground acceleration
expressed as a function of the gravity constant ‘g’.
Seismic zone factor

The ground response coefficients Ca and Cv are defined in UBC section
1629.4.3 and are parameters which reflect the potential amplification of the
ground vibration caused by different soil types. These coefficients are a
function of the zone factor Z, the soil profiles SA to SF and, where
applicable , the near source factors Na and Nv.
Ground response coefficients
 The fundamental period of a structure determines which of the two
coefficient Ca or Cv govern the seismic design of the structure. The
acceleration based coefficient Ca controls for shorter periods up to
approximately one second and the velocity based coefficient Cv controls for
longer periods.

Ground Response Coefficients

Soil Profile types
• The ground vibration caused by an earthquake tends to be
greater on soft soil than on hard soil or rock. As the vibration
propagates thought the material underlying the structure, it
may be either amplified or attenuated depending on the
fundamental period of the material. To account for this
potential amplification, six different soil types are identified in
the Code ranging from hard rock to soft soil .

Fundamental Period
• Each structure has a unique natural or
fundamental period of vibration which is the time
required for one cycle of free vibration. The
factors determining the fundamental period
include the stiffness and height of the structure,
and the fundamental period may vary from 0.1
seconds for a single-story building to several
seconds for a multi story building. As a first
approximation, the fundamental period may be
assumed equal to the number of stories divided
by 10.

 Two methods are provided in the Code for determining the
natural period of vibration, method A. and method B. Method A
utilizes UBC Formula (30-8) which is
T = Ct(hn)3/4 (1)
Where
hn = height in feet of the roof above the base, not including
the height of penthouses or parapets
Fundamental period
Ct = 0.035 for steel moment-resisting frames
= 0.030 for reinforced concrete moment-resisting
frames and eccentric braced steel frames
= 0.020 for all other buildings.

Response modification factor
The structure response modification factor R given in UBC
Table 16-N is the ratio of the seismic base shear, which would
develop in a linearly elastic system, to the prescribed design
base shear and is a measure of the ability of the system to
absorb energy and sustain cyclic inelastic deformations
without collapse.

Structural system R
Height limit,
ft o
Bearing wall system
Wood light-framed walls with shear panels 5.5 651 2.8
Concrete or masonry shear walls 4.5 160 2.8
Steel braced frames 4.4 160 2.2
Heavy timber braced frames 2.8 65 2.2
Building frame system
Steel eccentrically braced frame 7.0 240 2.8
Wood light-framed walls with shear panels 6.5 65' 2.8
Concrete shear walls 5.5 240 2.8
Masonry shear walls 5.5 160 2.8
Steel ordinary braced frames 5.6 160 2.2
Heavy timber braced frames 5.6 65 2.2
Steel special concentrically braced frames 6.4 240 2.2
Moment resisting frame system
Steel or concrete special moment-resisting frames
8.5 None 2.8
Masonry moment-resisting wall frames 6.5 160 2.8
Steel special truss moment frames 6.5 240 2.8

Structural system R
Height
limit, ft o
DUAL SYSTEM
Concrete shear walls with SMRF2
8.5 None 2.8
Masonry shear walls with SMRF 5.5 160 2.8
Masonry shear walls with masonry MRWF3
6..0 160 2.8
Steel eccentrically braced frames with steel SMRF 8.5 None 2.8
Steel ordinary braced frames with steel SMRF 6.5 None 2.8
Steel special concentrically braced frames with steel SMRF 7.5 None 2.8
Inverted Pendulum
Cantilevered column elements
2.2 354 2.0
Note: 1. Three stories or less
2. Special moment-resisting frame
3. Moment-resisting wall frame
4. Height of the columns included

Classification of structural systems
 UBC Section 1629.6 details five major categories of building
types distinguished by the method used to resist the lateral force.
These are illustrated in Figure-4 and consist of bearing walls,
building frames, moment-resisting frames, dual systems, and
cantilevered columns. These categories are further subdivided
into the types of construction material used. UBC Table 16-N lists
the different framing systems, with the height limitations and
response modification factors for each, together with the
restrictions imposed on the use of different building types in
specific seismic zones.

 In a bearing wall system, shear walls or
braced frames provide support for all or
most of the gravity loads and for resisting all
lateral loads. In general, a bearing wall
system has a comparably lower value for R
A building frame system has
separate systems to provide support
for lateral forces and gravity loads. A
frame provides support for essentially
all gravity loads with independent
shear walls or braced frames.

Moment-resisting frames are specially detailed to
provide good ductility and support for both lateral
and gravity loads by flexural action. In seismic
zones 3 and 4, the moment-resisting frames are
required to be specially detailed to satisfy UBC
Sections 1921 or 2211.
Dual system has a comparably higher value for R
since a secondary lateral support system is
available to assist the primary nonbearing lateral
support system. Nonbearing walls or bracing
supply the primary lateral support system with a
moment-resisting frame providing primary support
for gravity loads and acting as a backup lateral
force system.
The moment-resisting frame must be designed to
independently resist at least twenty-five percent of
the base shear.

 Essential facilities are defined in UBC Table 16-K as hospitals, fire and
police station, emergency response centers and buildings housing
equipment for these facilities. Hazardous facilities are defined as structures
housing materials which will endanger the safety of the public if released.
In order to ensure that essential and hazardous facilities remain functional
after an upper level earthquake, an importance factor I of 1.25 is assigned
to these facilities. This has the effect of increasing the prescribed design
base shear by twenty-five percent, and raises the seismic level at which
inelastic behavior occurs and the level at which the operation of essential
facilities is compromised.
Occupancy categories and importance factors

BASE SHEAR
*WHERE Cs=CvI/RT is siesmic response cooficient
Nv is near source factorStructural Designing Course

Load Combinations according to UBC-1997
FACTORED LOAD COMBINATIONS

ALLOWABLE OR SERVICE LOAD COMBINATIONS
Load Combinations according to UBC-1997

Eabs intro & Siesmic Terminologies UBC-1991

More Related Content

Similar to Eabs intro & Siesmic Terminologies UBC-1991

Recently uploaded

Eabs intro & Siesmic Terminologies UBC-1991