Analysis & Design Using ETABS

Analysis and Design of Buildings using ETABS

Asian Center for Engineering Computations and Software, AIT Asian Institute of Technology

Users’ Forum Manila, 2009

Analysis and Design of Buildings Using ETABS 9.5 Dr. Naveed Anwar, Keerati Tunthasuwat, Thuang Htut Aung

About ACECOMS and AIT „

The Asian Center for Engineering Computations and Software (ACECOMS) is a part of the Structural Engineering Field in the School of Engineering and Technology (SET) at the Asian Institute of Technology (AIT), Thailand.

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AIT is a postgraduate international institute established in 1959 with the mission “to develop highly qualified and committed professionals who play leading roles in the region's sustainable development and its integration into the global economy”.

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The Structural Engineering Field is one of the first programs to be established at AIT and has been as a strong academic and research program for almost fifty years. The program is well known for excellence in academic, research and industry partnership.

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Analysis and Design of Buildings using ETABS

About ACECOMS and AIT „

ACECOMS was established in 1995 as one of the first not-for-profit, self-sustaining outreach center in then the School of Civil Engineering to provide and interface between academic and research activities and the professional practice. Since its establishment., ACECOMS has been contributing significantly in the development and effective applications of computational technologies in structural and civil engineering through its activities

ACECOMS „ „

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ACECOMS, AIT

Carry-out research and development in engineering computational technology and software. Carry-out research and provide consultancy for the applications of computing tools on the real world problems Provide general and specialized consulting services and support for project design, system development, review and investigation etc. Provide trainings and technical support for development of knowledge, information and skills Establish networks and associations with regional academic institutions and professional organizations Disseminate practical information and knowledge · Encourage active participation of professionals

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Analysis and Design of Buildings using ETABS

Agenda Overview „ Handling Materials, Sections, Loads „ Handling Special Behavior „ Creating Complex Models „ Analysis for various purposes „ Interpreting and evaluating results „ Specific Questions „ What is Coming Next? „ Discussion „

Software Discussed ETABS „ SAP2000 „ SAFE „ CSICOL „

GEAR „ GRASP „

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Analysis and Design of Buildings using ETABS

Overall Process Define the Parameters and Properties „ Quick Modeling „ Import, Draw and Edit „ Select and Assign „ Analyze and Understand „ Design and Check „

Define and Preferences Basic Parameters to be used in Analysis and Design

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Analysis and Design of Buildings using ETABS

Define Coordinate System/Grids „

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For a regular or general system, the coordinate system is defined using an origin and orientation relative to the Global coordinate system. All coordinate systems follow the right-hand rule. The grid lines for a regular system are defined relative to X and Y (Cartesian) or r and theta (cylindrical). The grid lines for a general system are defined relative to X and Y only. A regular system is any coordinate/grid system having a Cartesian (rectangular) or cylindrical grid system. A general system is a system comprised of arbitrarily defined grid lines. The Global coordinate system always exists, and has its own grid. All other systems are user defined with respect to the Global system.

Define Coordinate System/Grids „

Configuration of alternate coordinate systems

Locate the system origin

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Analysis and Design of Buildings using ETABS

Define Coordinate System/Grids „

Configuration of alternate coordinate systems

Define Coordinate System/Grids „

How to determine regular system or general system „

To determine if a previously defined system is a regular or general system, access the Coordinate/Grid Systems form and highlight the system name in the Systems display area. If the Convert to General Grid check box is NOT checked (with the system name highlighted), the grid system is a regular system.

Regular system

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General system

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Analysis and Design of Buildings using ETABS

Define Coordinate System/Grids „

General System „

In general system, we can draw the arbitrary grid lines which does not need to perpendicular each other.

Define Coordinate System/Grids „

General System

General System

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Analysis and Design of Buildings using ETABS

Functions „ „

Response Spectrum Time History

Functions Response Spectrum Function For Seismic Analysis „ From Code (IBC2006, AASHTO, EuroCode 8 …etc.) „ User Define from File

Response Spectrum Function for UBC97

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Analysis and Design of Buildings using ETABS

Functions Time History Function „ „

From Built-in (Sine, Cosine, Ramp, Sawtooth…etc.) User Define from File

Time History Function for Sine Function

Quick Modeling Using Parametric Structures and Templates

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Analysis and Design of Buildings using ETABS

Templates

Steel Deck System

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Analysis and Design of Buildings using ETABS

Staggered Truss System

Flat Slab System

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Analysis and Design of Buildings using ETABS

Flat Slab with Perimeter Beams

Waffle Slab System

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Analysis and Design of Buildings using ETABS

Ribbed Slab System

Template „

Add template to existing model „

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Able to add the components from template to the existing model

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Analysis and Design of Buildings using ETABS

Export, Draw and Edit Creating Complex Geometry Efficiently

Import & Export Capability to import data from many structural engineering software to create the model „ Export the model to SAFE and other drawing software „

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Analysis and Design of Buildings using ETABS

Export to AutoCAD .dxf File

Export to AutoCAD .dxf File

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Analysis and Design of Buildings using ETABS

Drawing and Editing „

Points „

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Lines „ „

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Nodes, Supports etc. Frames, Beams, Trusses Cables

Areas „

Plate, Shell, Membrane

Move „ Replicate „ Extrude „ Edit Points „ Divide „ Mesh „

Replicate „

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Generating a large model from a small model when the objects and/or joints form a linear or radial pattern or are symmetrical about a plane or story. Different from Cut, Copy and Paste commands. Replicate command replicated the assignments and loads on the objects but Cut, Copy and Paste commands are NOT capable of copying the assignments or loads. Four types of replication „ „ „ „

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Linear Radial Mirror Story

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Analysis and Design of Buildings using ETABS

Extrude „

Sweep selected objects through space to create new objects of higher dimension „

Extrude points to lines „ Model

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circular-shaped beam

Extrude lines to areas „ Model

the ramp

Extrude

Model circular shaped beam by radial extrusion of point object

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Analysis and Design of Buildings using ETABS

Extrude

Model circular shaped ramp by radial extrusion of line object

Edit Point „

Merge joints „ „

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Align points „

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Merge the joints outside the auto merge tolerance. To eliminate the extraneous joints that may occur if the elements are drawn with snap turned off. If the floor area is manually meshed in irregular pattern and the different pattern loading is to be assigned, the edge of area elements should be aligned along the border of the pattern loading.

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Analysis and Design of Buildings using ETABS

Edit Point - Merge

Select the points to merge

Merge tolerance must be greater than distance between the points

Edit Point - Align

The floor elements are aligned along the border of different pattern loading Live load = 2 kN/m2

Live load = 5 kN/m2

To assign different pattern loading on irregular shaped meshed floor

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Draw the line along the border of pattern loading. Select the line and the points to be aligned

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Analysis and Design of Buildings using ETABS

Edit Lines Divide frames „ Join frames „ Trim/Extend frames „ Edit curved frame geometry „ Edit cable geometry „ Edit tendon profile „

Edit Lines „

Divide frames „

Divide the frame intersect with selected frames.

Select the frame object to bed divided and select the intersecting objects

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Join frames „

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Join the selected frame objects and remove the unused joints.

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Analysis and Design of Buildings using ETABS

Edit Areas - Divide „

Divide into the number of objects specified using the edit box for each edge.

Edit Areas - Divide „

Divide area into objects of given maximum size

10 elements

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Analysis and Design of Buildings using ETABS

Edit Areas - Divide „

Divide area based on points on area edges „

Divide based on specified lines and points. Program will not extend the selected line to make it intersect an edge; the selected line must already intersect an edge of the selected area object. The selected point must also intersect an edge of the selected object, not inside the selected object.

Edit Areas - Divide „

Divide area using cookie cut based on selected straight line objects „

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The selected line object does not need to intersect with the edge of the selected area object .

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Analysis and Design of Buildings using ETABS

Edit Areas - Divide „

Divide area into given number of objects „

The selected point object must lie either on the edge or inside the selected area object. The rotation in degrees of dividing lines can be specified from original local 1 and 2 axes.

Edit Areas - Divide „

Divide area using general divide tool based on selected points and lines „ „

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Divide the area object based on specified maximum dimension. The division lines intersect the selected points and concurrent with the selected lines.

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Analysis and Design of Buildings using ETABS

Edit Areas - Divide „

Local axes for added points Specify that the local axes definitions for new points added along the edges of an area object are the same as an adjacent area object corner point if the local axes definition for the adjacent corners are identical. „ Specify that the local axes definition for the new points on the face of the area object are set the same as a corner point of the area object if the local axes definitions for all of the corner points of the area object are identical. „

Edit Areas - Divide

Added points on the edge of original element have the same local axes with original element. If the second check box is checked, local axes of added points on the face of original element will be same.

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Analysis and Design of Buildings using ETABS

Edit Areas - Divide „

Restraints and constraints for added points „

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Specify that a restraint degree of freedom (or constraint) is added to new points on the edges of the area object if both adjacent corners have that degree of freedom restrained (constrained) and the local axes definitions for the adjacent corners and the new point are identical. Specify that a restraint degree of freedom (or constraint) is added to new points on the face of the area object if all area object corners have that degree of freedom restrained (constrained) and the local axes definitions of all corners and the new points are identical.

Edit Areas - Divide

Added points on the edge of original element have the same restraints with original element. If the second check box is checked, restraints of added points on the face of original element will be same.

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Analysis and Design of Buildings using ETABS

Edit Areas-Merge „ „ „

Selected areas essentially in the same plane and sharing a common edge or with overlapping area edges will be merged. Areas that lie one on top of the other or that share no common or overlapping edges will not be merged. Choose an area that has assignments suitable for the merged area.

Edit Areas-Merge

Maintain the assignments for Area 7 Area 6

Area 7

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Analysis and Design of Buildings using ETABS

Edit Areas „

Expand/Shrink areas „ „

A positive value expands the area and a negative value shrinks the area. The offset distance is measured perpendicular to the area edge.

Offset all area edges

100

100

100

100

Select the edge or whole area

Edit Areas

100

Select the edge

Offset selected area edges only

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Analysis and Design of Buildings using ETABS

Edit Areas The offset for points is measured along a bisector angle formed by the area edges adjacent to the selected point(s).

10 0

Select the point and area

Offset selected points of selected areas only

Edit Areas „

Add point to area edge „ „

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Add points to the edges at the midpoint between the existing points of the selected object. This procedure can do repeatedly as many times as needed.

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Analysis and Design of Buildings using ETABS

Edit Areas „

Remove points from area „ „

Select the area and the point to be removed. If the point was not colinear with the remaining points, the area object will be reshaped.

Special Tools Handling Special Problems and Behavior

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Analysis and Design of Buildings using ETABS

Basic Modeling Techniques Behavior „ Constraints „ Restraints „ Springs „ Nonlinear

Links „ Nonlinear Hinges „ Element End Conditions „ Dummy elements

Link/Support Element „ „

A Link element is a two-joint connecting link. A Support element is a one-joint element

Link Element

Support Element

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Analysis and Design of Buildings using ETABS

Link/Support Element Type of Link/Support Element available in ETABS „ „ „ „ „ „ „

Linear Damper Gap Hook Plastic1 Isolate1 Isolate2

Link/Support Element „ „

Damper Element Gap Element „

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Hook Element „

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Compression only (for example Spread Footing)

Tension only (for example Tie Rod)

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Analysis and Design of Buildings using ETABS

Diaphragms In ETABS: Only diaphragms is available as constraint option for joint and shell element

Diaphragms Rigid Option „ Fully rigid diaphragm is assumed

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Analysis and Design of Buildings using ETABS

Diaphragms Semi Rigid Option: „ The in-plane rigidity of the diaphragm comes from the stiffness of the objects that are part of the diaphragm „ Used to calculate the dimension of diaphragm in application of the wind/static equivalent earthquake loading

Select and Assign Connecting Geometry with Defined Parameters

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Analysis and Design of Buildings using ETABS

Select and Assign Many tools to select the drawn objects „ Many types of assignments „

Sections „ Loads, Temperature, Joint Patters „ Constraints, Restraints, Releases „ Special modifications „ Axis, Insertion Points, Offsets „ Local material changes „

Analyze and Understand Getting the Required Response and Understanding Behavior

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Analysis and Design of Buildings using ETABS

Analysis Case „

Static Linear Static „ Nonlinear Static (Included Push Over) „ Staged Construction „

Response Spectrum „ Time History „

Linear Time History „ Nonlinear Time History „

Analysis Case „

Static: Linear: The most common type of analysis. Loads are applied without dynamical effects. „ Nonlinear: Loads are applied without dynamical effects. May be used for pushover analysis, and other types of nonlinear problems. (Pushover + P-Delta) „

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Nonlinear Staged Construction: The definition of a nonlinear direct-integration time-history analysis case for staged construction.

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Analysis and Design of Buildings using ETABS

Analysis Case

3 2 1

Nonlinear Staged Construction

Analysis Case „

Modal: Calculation of dynamic modes of the structure using the Eigenvector or Ritz-vector method. Loads are not actually applied, although they can be used to generate Ritz vectors.

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Analysis and Design of Buildings using ETABS

Analysis Case „

Response Spectrum. Statistical calculation of the response caused by acceleration loads. Requires response-spectrum functions.

Response Spectrum Function

Analysis Case „

Time History: „

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Linear Time History. Time-varying loads are applied. Requires time-history functions. All objects behave linearly. Period. Specify a single cycle of the periodic function and assumes that the specified cycle continues indefinitely. All objects behave linearly. Nonlinear Time History. Time-varying loads are applied. Requires time-history functions. Nonlinear dynamic properties assigned to link elements are considered.

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Analysis and Design of Buildings using ETABS

Pushover Analysis

Pushover Analysis Available Hinge Properties „ „ „ „ „ „ „

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Axial P Shear V2 Shear V3 Moment M2 Moment M3 Torsion T Interaction P-M2-M3

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Analysis and Design of Buildings using ETABS

Pushover Analysis Hinge Property Data Displacement Controlled

Pushover Analysis Pushover Curve „

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Resultant Base Shear vs Monitored Displacement

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Analysis and Design of Buildings using ETABS

Pushover Analysis Pushover Curve „

ATC-40 Capacity Spectrum

ATC-40 Capacity Spectrum

Show Response Spectrum Curve „

Create from Time History Case at Particular Joint

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Frequency or Period Versus

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Spectral Displacement Spectral Velocity Pseudo Spectral Velocity Spectral Acceleration Pseudo Spectral Acceleration

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Analysis and Design of Buildings using ETABS

Show Plot Function Energy Function Input, Kinetic, Potential Modal Damping Link Damper, Energy Error „ Base Function „ Joint Displacement/Forces „ Frame Forces „ Pier Forces „ Spandrel Forces „

Show Plot Function

Base Function

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Displacement Function

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Analysis and Design of Buildings using ETABS

Energy/ Virtual Work Function Figure "a," that has lateral loads P1 and P2 at the Roof and Second story levels, respectively. Also note the displaced shape, D, associated with this structure and loading, which is shown as a dashed line.

Energy/ Virtual Work Function Figure "b", with a single load P (typically a unit load) applied to it and a resulting displaced shape, d, shown as a dashed line. Maxwell's Reciprocal Theorem states that: Pδ = P1 δ roof + P2 δ second

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Analysis and Design of Buildings using ETABS

Energy/ Virtual Work Function In this very simple example, the equation above could be reduced to an element level where the elements are illustrated in Figure "c" as: P δ = [P1 δ roof - P1 δ second] + [(P1 + P2) δ second]

Energy/ Virtual Work Function P δ = [P1 δ roof - P1 δ second] + [(P1 + P2) δ second] ETABS show the energy diagram, it reports the equivalent of the values shown in brackets in the above equation of the background information for each element in the structure. Note the following about the energy values that ETABS reports:

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Analysis and Design of Buildings using ETABS

Energy/ Virtual Work Function P δ = [P1 δ roof - P1 δ second] + [(P1 + P2) δ second] They are based on all six degrees of freedom of the element, not just the one degree of freedom described in the Figure and the associated equations in the background information. They are determined as follows: „ ETABS determines the energy per unit volume associated with each element in the structure. „ ETABS normalizes all of the calculated energy values such that the largest one has a value of 100.

Energy/ Virtual Work Function Sample of Energy/ Virtual Work Diagram due to Wind Load

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Analysis and Design of Buildings using ETABS

Time History Traces Available Functions for Time History Traces „ Input Function „ Energy Function „ Base Function „ Point Displacement/ Forces „ Line Element Forces „ Pier Forces „ Spandrel Forces

Time History Traces Input Function = Input Time History Function

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Analysis and Design of Buildings using ETABS

Time History Traces Energy Function

Time History Traces Energy Function

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Analysis and Design of Buildings using ETABS

Time History Traces Base Function = Total Base Reaction Function

Time History Traces „ „ „ „

Point Displacement/ Forces Line Element Forces Pier Forces Spandrel Forces

Point

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Line

Displacement/ Forces at Particular Element and Location

Pier

Spandrel

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Analysis and Design of Buildings using ETABS

Time History Traces „ „ „ „

Point Displacement/ Forces Line Element Forces Pier Forces Spandrel Forces

Displacement/ Forces at Particular Element and Location

Element ID Location Force Component

Outrigger System

No Outrigger

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Outrigger

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Analysis and Design of Buildings using ETABS

Shear Force in Beams due to Lateral Load (No Outrigger Wall)

3.14 T

3.25 T

4.24 T

Shear Force in Beams due to Lateral Load (Outrigger Wall)

2.58 T

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2.41 T

2.95 T

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Analysis and Design of Buildings using ETABS

Axial Force in Columns due to Lateral Load (No Outrigger Wall)

623 T

350 T

383 T

Axial Force in Columns due to Lateral Load (Outrigger Wall)

746 T

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580 T

484 T

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Analysis and Design of Buildings using ETABS

Bending Moment due to Lateral Load (No Outrigger Wall)

8.3

8.6

11.3

40.2

38.3

36.9

Bending Moment due to Lateral Load (Outrigger Wall)

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6.9

6.4

7.9

33.7

31.1

29.1

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Analysis and Design of Buildings using ETABS

Top Displacement due to Lateral Load Top Displacement = 75 cm

Top Displacement = 40 cm

Construction Sequence Analysis

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Analysis and Design of Buildings using ETABS

Construction Sequence Analysis

Deflected Shape due to DL (Linear Analysis)

Deflected Shape due to DL (Construction Sequence Analysis)

Construction Sequence Analysis

1018 T

16135 T

1141 T

1011 T

Axial Force due to DL at the Base (Linear Analysis)

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1101 T

15333 T

1248 T

1035 T

Axial Force due to DL at the Base (Construction Sequence Analysis)

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Analysis and Design of Buildings using ETABS

Construction Sequence Analysis

11.3

Bending Moment due to DL (Linear Analysis)

12.4

Bending Moment due to DL (Construction Sequence Analysis)

Construction Sequence Analysis

8.9

Shear Force due to DL (Linear Analysis)

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9.3

Shear Force due to DL (Construction Sequence Analysis)

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