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Civl512/Mech 539Finite Element MethodsFinite Element Modeling of Building Structures

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Overall Design ProcessOverall Design Process

Conception

Modeling

Analysis

Design

Detailing

Drafting

Costing

IntegratedIntegratedDesignDesign

ProcessProcess

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Building Systems

Building is an assemblage of various Systems

Basic Functional System

Structural System

Plumbing and Drainage System

Electrical, Electronic and CommunicationSystem

Security System Other specialized systems

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Beams, Columns, One-way/Two-way Slabs, Flat Slabs,

Transfer Plates, Shear Walls, Deep Beams

Sub-structure and Member Design

Frame and Shear WallsLateral Load Resisting System

Floor Slab SystemGravity Load Resisting System

Building Structure

Floor Diaphragm

The Building Structural System - Physical

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The Building Structural System - Conceptual

The Gravity Load Resisting System (GLRS)

The structural system (beams, slab, girders, columns, etc)that act primarily to support the gravity or vertical loads

The Lateral Load Resist ing System (LLRS)

The structural system (columns - tubular structure, shear

walls, bracing, etc) that primarily acts to resist the lateralloads

The Floor Diaphragm (FD)

The structural system that transfers lateral loads to thelateral load resisting system and provides in-plane floorstiffness

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Building Response

Objective: To determine the load path for gravity and lateral loads

For Gravity Loads - How Gravity Loads are Distributed

Analysis of Gravity Load Resisting System for:

Dead Load, Live Load, Cladding Loads, temperature,

shrinkage, creep

Important Elements: Floor slabs, beams, columns, openings,J oists, etc.

For Lateral LoadsHow Lateral Loads are Distributed

Analysis of Lateral Load Resisting System for:

Wind Loads, Seismic Loads, Structural Un-symmetry

Important elements: Columns, shear walls, bracing , beams

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Structural Response To LoadsStructural Response To Loads

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STRUCTURE

pv

EXCITATION

Loads

Vibrations

SettlementsThermal Changes

RESPONSES

Displacements

Strains

StressStress Resultants

Structural System

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Analysis of Structures

pv

xx yy zzvxx y z

p+ + + = 0

Real Structure is governed by Partial

Differential Equations of various order

Direct solution is only possible for:

Simple geometry Simple Boundary

Simple Loading.

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We would like to predict the structural response before

the structure is being constructed

Real structure are not available for analysis

We therefore need tools to Model the

Structure and to Analyze the Model

The Need for Modeling

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StructuralModel

The Need for Structural Model

EXCITATION

Loads

Vibrations

SettlementsThermal Changes

RESPONSES

Displacements

Strains

StressStress Resultants

STRUCTURE

pv

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Finite Element Analysis (FEA)

A discretized solution to a continuum

problem using FEM

Finite Element Method (FEM)

A numerical procedure for solving (partial)

differential equations associated with fieldproblems, with an accuracy acceptable to

engineers

Throughout the semester, you have alreadylearnt the foundation of FEM:-

- The matrix structural analysis technique

- Different element types for FEM

Finite Element Method: The Analysis Tool

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(Governed by partial

differential equations)

CONTINUOUS MODEL

OF STRUCTURE

(Governed by either

partial or total

differential equations)

DISCRETE MODEL

OF STRUCTURE

(Governed by algebraic

equations)

3D-CONTINUM

MODEL

Continuum to Discrete Model

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xx yy zz

vxx y zp+ + + =0

t

v

t

s

t

vdV p udV p uds

_ _ _

= +

Assumptions

Equilibrium

Compatibility

Stress-Strain Law

(Principle of Virtual Work)

Partial

Differential

Equations

Classical

Actual Structure

Kr R=

Algebraic

Equations

K = Stiffness

r = Response

R = Loads

FEM

Structural Model

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Simplified Structural System

Loads (F) Deformations (D)

Fv

F = K DF = K D

FF

KKDD

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EXCITATION RESPONSES

STRUCTURE

pv

Static

Dynamic

Static

Dynamic

Elastic

Inelastic

Elastic

Inelastic

Linear

Nonlinear

Linear

Nonlinear

Simplified Structural System

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Static Vs Dynamic Static Excitation

When the Excitation (Load) does not vary rapidly with Time When the Load can be assumed to be applied Slowly

Dynamic Excitation

When the Excitation varies rapidly with Time

When the Inertial Force becomes significant

Most Real Excitation are Dynamic but are consideredQuasi Static

Most Dynamic Excitation can be converted toEquivalent Static Loads

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Elastic Vs Inelastic Elastic Material

Follows the same path during loading and unloading andreturns to initial state of deformation, stress, strain etc.after removal of load/ excitation

Inelastic Material

Does not follow the same path during loading andunloading and may not returns to initial state ofdeformation, stress, strain etc. after removal of load/excitation

Most materials exhibit both, elastic and inelastic behaviordepending upon level of loading.

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Linear Vs Nonlinear Linearity

The response is directly proportional to excitation

(Deflection doubles if load is doubled)

Non-LinearityThe response is not directly proportional to excitation

(deflection may become 4 times if load is doubled)

Non-linear response may be produced by:

Geometric Effects (Geometric non-linearity) Material Effects (Material non-linearity)

Both

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Action

Deformation

Action

Deformation

Action

Deformation

Action

Deformation

Linear-Elastic Linear-Inelastic

Nonlinear-Elastic Nonlinear-Inelastic

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Basic Steps in FEAasic Steps in FEAEvaluate Real Structure

Create Structural Model

Discretize Model in FE

Solve FE Model

Interpret FEA Results

Physical significance of Results

Engineer

Engineer + Software

Software

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X

Z

Y

Membrane/ PanelIn-Plane, Only Axial

ShellIn-Plane and Bending

Plate/ SlabOut of Plane, Only Bending

General Solid

Regular Solid

Plate/ Shell

( T small compared to Lengths )

( Orthogonal dimensions)

Beam ElementSolid Element

H, B much less than L

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Global Modeling of StructuralGeometry

(b) Solid Model (c) 3D Plate-Frame (d) 3D Frame

(a) Real Structure

(e) 2D Frame

Fig. 1 Various Ways to Model a Real Struture

(f) Grid-Plate

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1 D Elements (Beam type)

Can be used in 1D, 2D and

2D

2-3 Nodes. A, I etc.

2 D Elements (Plate type)

Can be used in 2D and 3DModel

3-9 nodes. Thickness

3 D Elements (Brick type)

Can be used in 3D Model

6-20 Nodes.

Truss and Beam Elements (1D,2D,3D)

Plane Stress, Plane Strain, Axisymmetric , Plate and Shell Elements (2D,3D)

Brick Elements

Dimensions of Elements

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11

33

22

33

22

++

PP+V2+V2

+V3+V3

+V3+V3

+V2+V2+P+P

11

33

22

33

22

++

TT+M2+M2

+M+M

33

+M+M

33

+M+M

22 +T+T

Frame Six DOF at Both Ends

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Ignore bending stiffness

Tension / Compression

In- plane Shear

For in plane loads

Principle Stresses

suitable for very thinstructures / members

Thin Walled Shells,

Specially Suitable for FerroCement Structure

Membrane

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Membrane ElementGeneral

Total DOF per Node = 3 (or 2)

Total Displacements per Node = 2

Total Rotations per Node = 1 (or 0)Membranes are modeled for flat surfaces

Application

For Modeling surface elements carryingin-plane loads

Building Specific Application

For representing floor slabs for Lateral

Load Analysis.

Model Shear walls, Floor Diaphragm

etc

Membrane

U1

Node 1

R3U2

U1

Node 3

R3 U2

U1

Node 4

R3

U2

U1

Node 2

U2

3 2

1

Membrane

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1 unit

330

230

130

22

12

11

x1

x3

x2

3D Problem

2D Problem

Plain-Strain

Assumptions

12

22

11

x2

x1

Plane Stress ProblemPlane Strain Problem

Plane Stress and Plane Strain

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Primarily Bending mode

Moment and Shear arepredominant

Suitable for moderately

thick slabs and plates

For Out-of-plane loads only

Can be used in 3D or 2D

models

Suitable for planks andrelatively flat structures

Plate

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Plate ElementGeneral

Total DOF per Node = 3


Total Rotations per Node = 2

Plates are for flat surfaces

Application

For Modeling surface elementscarrying

out of plane loads

Building Specific ApplicationFor representing floor slabs for

Vertical

Load Analysis

Model slabs

R1

Node 1

U3R2

1

23

R1

Node 2

U3R2

R1

Node 3

U3 R2

R1

Node 4

U3 R2

Plate

Plate

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Combined Membrane andPlate

Suitable for general applicationto surface structures

Suitable for curved structures

Thick shell and thin shell

implementations available Membrane thickness and plate

thickness can be specifiedseparately

Numerous results generated.Difficult to design the sectionfor combined actions

Plate-Shell

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General

Total DOF per Node = 6 (or 5)


Total Rotations per Node = 3

Used for curved surfaces

Application

For Modeling surface elementscarrying general loads

Building Specific Application

May be used for modeling of generalslabs systems. But not used generally

1

23

U1, R1Node 3

U3, R3

U2, R2

U1, R1

Node 1

U3, R3 U2, R2

U1, R1

Node 4

U3, R3

U2, R2

U1, R1

Node 2

U3, R3

U2, R2

Shell

Shell

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Shear Axial deformation mode

in 3D

Suitable for micro-models Suitable for very thick plates /

solids

May not be applicable much toferocement structures

Use 6 to 20 node

elements

Solid

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Simple Supports

Fix, Pin, Roller etc.

Support Settlement

Elastic Supports

Spring to represent soil

Using Modulus of Sub-grade

reaction

Full Structure-Soil Model Use 2D plane stress elements

Use 3D Solid Elements

Soil-Structure Interaction

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OKOKDx, DzDzOKOKSolid

Rx, RzOKDx, DzRx, Ry,

Rz, DzOK

Rx, Ry,

Rz

Shell

Rx, RzOKOKRx, RzOKRx, RzPlate

OKOKDx, DyOKOKOKMembrane

Rx, Ry,

RzRx ?

Rx ?

Dx, Dy

Rx, Ry,

Rz, DzOK

Rx, Ry,

Rz

Frame

OKOKOKDzOKOKTruss

SolidShellPlateMembr

ane

FrameTruss

0

Orphan Degrees Of Freedom:

1 2 3 4

Connecting Different Types of Elements

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Vertical Load Resisting SystemsVertical Load Resisting Systems

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Purpose

To Transfer Gravity Loads Applied at the Floor Levels

down to the Foundation Level

Direct Path Systems

Slab Supported on Load Bearing Walls

Slab Supported on Columns

Indirect Multi Path Systems

Slab Supported on Beams

Beams Supported on Other Beams

Beams Supported on Walls or Columns

Gravity Load Resisting Systems

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1. Slabs supported on Long Rigid Supports

Supported on stiff Beams or Walls

One-way and Two-way Slabs Main consideration is flexural reinforcement

2. Slab-System supported on Small Rigid Supports

Supported on Columns directly Flat Slab Floor systems

Main consideration is shear transfer, moment distribution invarious parts, lateral load resistance

3. Slabs supported on soi l

Slabs on Grade: Light, uniformly distributed loads

Footings, Mat etc. Heavy concentrated loads

Vertical Load Resisting Systems

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Direct Load Transfer Systems (Single load transfer path)

Flat Slab and Flat Plate

Beam-Slab

Waffle Slab

Wall J oist

Indirect Load Transfer System (Multi step load transfer

path)

Beam, Slab

Girder, Beam, Slab Girder, J oist

Popular Gravity Load Resting Systems

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For Wall Supported Slabs

Assume load transfer in One-Way or Two-Waymanner

Uniform, Triangular or Trapezoidal Load on Walls

For Beam Supported Slabs

Assume beams to support the slabs in similar waysas walls

Design slabs as edge supported on beams

Transfer load to beams and design beams for slab

load

For Flat-Slabs or Columns Supported Slabs

Assume load transfer in strips directly to columns

Conventional Approach

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Popular Gravity Load Resting Systems

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Single PathSlab On Walls

Single PathSlab on Columns

Dual PathSlab On Beams,

Beams on Columns

Gravity Load Transfer Paths

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Mixed PathSlab On Walls

Slab On Beams

Beams on Walls

Complex PathSlab on Beams

Slab on Walls

Beams on Beams

Beams on Columns

Three Step PathSlab On Ribs

Ribs On Beams

Beams on Columns

Gravity Load Transfer Paths

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Simplified Load Transfer

Transfer of Area Load

To Lines To Points To Lines and Points

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Load Transfer Through Slab and Beam

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Slab Deformation and Beams

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5.0m

Slab T = 200 mmBeam Width, B = 300 mmBeam Depth, Da) 300 mmb) 500 mmc) 1000 mm

D

B

Slab System Behavior

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Effect of Beam Size

on

MomentDistribution

a) Beam Depth = 300 mm

b) Beam Depth = 500 mmc) Beam Depth = 1000 mm

Moment Distribution in Beam-Slab

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Effect of Beam Size on Moment Distribution

a) Beam Depth = 300 mm b) Beam Depth = 500 mm c) Beam Depth = 1000 mm

Moment Distribution in Beam-Slab

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By default uses two-way load transfer

mechanism

Simple RC solid slab

Can also be used to model one way slabs

Area Objects: Slab

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Use one-way load transfer mechanism

Metallic Composite SlabsIncludes shear studs

Generally used in association with

composite beams

Deck slabs may be

o Filled Deck

o Unfilled Deck

o Solid Slab Deck

Area Objects: Deck

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Lateral Load Resisting SystemsLateral Load Resisting SystemsLateral Load Resisting Systems

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Purpose

To Transfer Lateral Loads Applied at any location in the structure

down to the Foundation Level

Single System

Moment Resisting Frames

Braced Frames

Shear Walls Tubular Systems

Outrigger System

Dual System Shear Wall + Frames

Tube + Frame + Shear Wall

Lateral Load Bearing Systems

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Primary Lateral Loads

Load generated by Wind Pressure

Load generated due to Seismic Excitation

Other Lateral Loads

Load generated due to horizontal component ofGravity Loads in Inclined Systems and in Un-symmetrical structures

Load due to lateral soil pressure, liquid and materialretention

Lateral Load

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Bearing wall system

Light frames with shear panels

Load bearing shear walls

Fully Braced System (FBS)

Shear Walls (SW)

Diagonal Bracing (DB)

Moment Resisting Frames (MRF) Special Moment-Resisting Frames (SMRF)

Concrete Intermediate Moment-Resisting Frame (IMRF)

Ordinary Moment-Resisting Frame (OMRF)

Dual Systems (DS) Shear Walls + Frames (SWF)

Ordinary Braced Frame (OBF)

Special Braced Frame (SBF)

Sample Lateral Load ResistanceSystems

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The Load is transferred by

shear in columns, that

produces moment in columns

and in beams

The Beam-Column

connection is crucial for the

system to work

The moments and shear fromlater loads must be added to

those from gravity loads

Moment Resisting Frame

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Structural Form Rigid frame structure

Low rise buildings

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The Walls are part of the

frame and act together with

the frame members

The lateral loads is primarily

resisted by the shear in the

walls, in turn producing

bending moment.

Partial loads is resisted by the

frame members in moment

and shear

Shear Wall - Frame

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Structural Form Wall frame structure

Low to medium rise buildings

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The lateral loads is primarily

resisted by the Axial Force in

the braces, columns and beamsin the braced zone.

The frame away from the

braced zone does not have

significant moments

Bracing does not have to be

provided in every bay, but

should be provided in every

story

Braced Frame

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The system is formed by using

closely spaced columns and deep

spandrel beams

The lateral loads is primarilyresisted by the entire building

acting as a big cantilever with a

tubular/ box cross-section

There is a shear lag problembetween opposite faces of the tube

due to in-efficiency of column beam

connection

The height to width ratio should bemore than 5

Tubular Structure

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Structural Form Tubular Structure

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Diagonal Braces are added to

the basic tubular structure This modification of the

Tubular System reduces shear

lag between opposite faces

Braced Tube Systems

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Structural Form Out-rigger Structure

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1. 2D Frame Models

Convert building in to several 2D frames in each direction Suitable for symmetrical loads and geometry

2. 3D Frame Model

Make a 3D frame model of entire building structure

Can be open floor model or braced floor model3. Full 3D Finite Element Model

A full 3D Finite Element Model using plate and beamelements

4. Rigid Diaphragm Model

A special model suitable for buildings that uses theconcept of Rigid Floor Diaphragm

Modeling for Lateral Loads

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Convert 3D Building to an assemblage of 2D Frames

Using Independent Frames

Using Linked Frames Using Sub-Structuring Concept

Advantages

Easier to model, analyze and interpret

Fairly accurate for Gravity Load Analysis Main Problems:

Center of Stiffness and Center of Forces my notcoincide

Difficult to consider building torsional effects

Several Frames may need to be modeled in eachdirection

Difficult to model non-rectangular framing system

Modeling as 2D Frame

Create a Simple 2D ModelCreate a Simple 2D Model

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1. Consider the

Structure Plan and 3D

View

2. Select and

isolate

Typical 2D

Structure

4. Obtain results

3. Discretize

the Model,

apply loads

Using Linked FramesUsing Linked Frames

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Plan

Modeling

Shear Wall

Typical Frame

Elevation

Linked Elements

Link Element can allow only to transmit the shear

and axial force from one end to other end. It has

moment discontinuity at both ends

Link Element act as a member which links the forces

of one frame to another frame, representing the effect

of Rigid Floor.

F3

F2

F1

F1

F2 F3

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The columns and beams are modeled by using beamelements

The slabs and shear walls are modeled by using shellelements

Enough elements in each slab panel must be

used if gravity loads are applied to the slabs If the model is only for lateral analysis, one

element per slab panel may be sufficient to modelthe in-plane stiffness

Shear walls may be modeled by plate or panel orplane stress element. The out of plane bending isnot significant

Full 3D Finite Element Model

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Example:

Uses more than 4000beam and plate elements

Suitable for analysis for

gravity and lateral loads

Results can be used fordesign of columns and

beams

Slab reinforcement

difficult to determinefrom plate results

Full 3D Finite Element Model

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Use Plate

Elements

Use Diagonal

Bracing Use Plate Elements

Panels, Plane Stress

Use Diagonals

In 3D Frame Models

Use Conceptual Rigid Diaphragm

Link Frames in 2D

Master DOF in 3D

Use Approximately

Modeling of Floor Diaphragm

The Rigid Floor Diaphragm

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Combines the simplicity and advantages of the 2D Frame

models with the accuracy of the 3D models

Basic Concept:

The building structure is represented by vertical units (2DFrames, 3D Frames and Shear Walls), connected by the

invisible rigid diaphragmThe lateral movement of all vertical units are connected to

three master degree of freedom

This takes into account the building rotation and its effect

on the vertical units.The modeling and analysis is greatly simplified and made

efficient

The Rigid Floor Diaphragm

Rigid Floor Diaphragm Concept

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Modeled as Rigid Horizontal Plane of infinite

in-plane stiffness (in X-Y plane) Assumed to have a hinge connection with

frame member or shear wall, so flexural

influence of all floors to lateral stiff ness is

neglected

All column lines of all frames at particular

level can not deform independent of each

other

The floor levels of all frames must be at the

same elevation and base line, but they need

not have same number of stories

Rigid Floor Diaphragm Concept

How RFD Concept Works

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UL

UL1

UL2

UL3

X

Y

F3 , 2

F1 ,1

F3 ,3

uilding d.o.f.s

F2 , 1

r x

r rY

Local Frame DOF

How RFD Concept Works

When Single Rigid Floor Cannot be Used

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When Single Rigid Floor Cannot be Used

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MeshingMeshingMeshing

Basic Floor Modeling Object

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Points

Columns

Load Points Boundary Point

Lines

Beams

Areas Deck: Represents a Steel Metal Deck, One way Load Transfer

Slab: Represents one-way or two-way slab portion

Opening: Represents Openings in Floor


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Meshing Slabs and Walls

In general the mesh in the slabshould match with mesh in the

wall to establish connection

Some software automaticallyestablishes connectivity by

using constraints or Zipper

elements

ZipperZipper

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ETABS automatically meshes all line objects with frame sectionproperties into the analysis model

ETABS meshes all floor type (horizontal) area objects (deck or slab)into the analysis model

Meshing does not change the number of objects in the model

To mesh line objects with section properties use Edit menu > DivideLines

To mesh area objects with section properties use Edit menu > MeshAreas


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Automatic Meshing of Line Objects

Frame elements are meshed at locations where other frameelements attach to or cross them and at locations where point

objects lie on them.

Line objects assigned link properties are never automatically

meshed into the analysis model by ETABS

ETABS automatically meshes (divides) the braces at the point

where they cross in the analysis model

No end releases are introduced.

Automatic Meshing

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ETABS automatically meshes a floor-type area object up into four-sided (quadrilateral) elements

Each side of each element of the mesh has a beam (Real orImaginary) or wall running along it

ETABS treats a wall like two columns and a beam where the

columns are located at the ends of the wall and the beam connectsthe columns.

Each column is assumed to have four beams connecting to it

The floor is broken up at all walls and all real and imaginary beamsto create a mesh of four-sided elements

Automatic Meshing of Area Objects

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LoadingLoadingLoading

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Load Transfer Path For Gravity Loads Most loads are basically Volume Loads generated due to

mass contained in a volume

Mechanism and path must be found to transfer these loadsto the Supports through a Medium

All types of Static Loads can be represented as:

Point Loads

Line Loads Area Loads

Volume Loads

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The Load Transfer Path The Load is transferred through a medium which may be:

A Point

A Line An Area

A Volume

A system consisting of combination of several mediums

The supports may be represented as:

Point Supports

Line Supports

Area Supports Volume Supports

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Graphic Object RepresentationObject

Line

Area

Volume

Point LoadConcentrated Load

Beam Load

Wall Load

Slab Load

Slab Load

Wind Load

Seismic LoadLiquid Load

Node

Beam / Truss

Connection Element

Spring Element

Plate Element

Shell Element

Panel/ Plane

Solid Element

Point SupportColumn Support

Line Support

Wall Support

Beam Support

Soil Support

Soil Support

Point

LoadGeometry

Medium

Support

Boundary

ETABS uses graphic object modeling concept

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ETABSETABSETABS

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ETABS Nonlinear For nearly 30 years ETABS has been recognized as the

industry standard for Building Analysis and DesignSoftware.

ETABS is the solution, whether you are designing asimple 2D frame or performing a dynamic analysis of acomplex high-rise that utilizes non-linear dampers forinter-story drift control.

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Objective By performing a finite element analysis on a structure:-

Predict the top drift of the structure under differentload cases.

Predict the critical forces acting on a particularelement.

Predict the natural frequencies of the structure.

Predict the dynamic performance.

Design the member sizes to comply with the codesrequirement.

Etc.

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IntroductionGeneral procedure for computerized FEM

modeling and analysis

Study the structure Propose aims/objectives of structural analysis

Select the type of analysis Select the computer package to perform the

analysis Define materials, element/section properties

Draft the model Assign load cases Run the analysis and extract the useful data

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ETABS Key Characteristics

A wide variety of automated templates allow a quickstart for almost any building.

Units that can be changed at any time.

Fully integrated Section Designer allows definition ofcomplex sections.

Static and dynamic, linear and nonlinear analysisoptions.

Fully interactive design for American, Canadian andBritish design codes.

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ETABS

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AnalysisStaged construction(construction sequence loading)

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AnalysisStatic Analysis

Dynamic Analysis(Modal Analysis)

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AnalysisDynamic response spectrum analysis

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AnalysisTime history analysis

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AnalysisNonlinear element analysis

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OutputDeformed Shape

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OutputBending moment, shear force, axial force diagrams

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OutputStress contours

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DesignSteel frame design(BS 5950)

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DesignConcrete frame/ Composite beam/ Shear wall design(BS 8110)

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Assumption in ETABSTo avoid instabilities and to reduce computational demand,

ETABS assume some ideal conditions. These assumptionshave been proved to be valid in most cases but one shouldalways check against these assumptions when dealing withspecial structures.

Rigid Floor Diaphragm

End Pier

P-delta Effect

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Rigid Floor DiaphragmIn ETABS a rigid diaphragm translates within its own plane (global X-Y plane) androtates about an axis perpendicular to its own plane (global Z-axis) as a rigid body.Designating point objects as a rigid diaphragm has no effect on the out-of-plane

behavior of the point objects.

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End Pier

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P-delta Effect

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ETABS Example on using ETABS

4 story building

Steel frame structure

1st story = 4.5m

Remaining stories = 3.8m/story All slabs = 75mm thk.

Cladding load =3.5kN/m

Dead load = 1.5kN/m 2 Live load = 5kN/m 2

Open New Model by selecting file -> New Model, select the unit KN,m,Cand select the

template Grid Only. You are recommended to change the view to help yourselfidentify/draw your members, this can be done by selecting the appropriate view iconlocated along the top edge of the interface window

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located along the top edge of the interface window.

Introduction to interface

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Drafting Commands

Set Select ModeToggle to selection modeClick on element to selectDrag from left to right to select elements enclosed by the drag areaDrag from right to left to select elements touched by the drag areaClick on selected element to unselect

Draw Frame/CableClick on the main window to assign ends of frame element(s)Select the pre-defined element from the Propertieswindow

Quick Draw Frame/Cable

Click on any grid line to assign frame element to the grid sectionDrag to assign frame elements to all enclosed empty grid lines


D fti C d

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Drafting Commands

Quick Draw Braces

Quick Draw Secondary BeamsSelect the number of Secondary Beams assigned within the selectedarea, theconnection type and the orientation from the Propertieswindow

Draw Quad AreaSelect 4 points to assign area element

Draw Rectangular Area ElementSelect 2 corners to assign rectangular area element

Quick Draw Area ElementSelect any point to assign area element enclosed by the nearest gridlines


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Drafting Commands

The Selection Tools

Select All (Ctrl + A)Get Previous SelectionClear SelectionSelect Using Intersecting Line

Snap Tools

Snap to Points and Grid IntersectionSnap to Ends and Midpoints

Import UB & UC for BS Standard by selecting the Define -> Frame Sections.Select. Choose add auto-select list from the right and add all the available members to

the list.

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One can draw columns and beams one by one. However, for building structures, thesame floor plan usually applies to multi-stories. To draw elements on similar stories,select Edit -> Edit story data -> Edit story to open the window below, select story 4 asmaster story and all remaining stories as similar to story 4.

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Add columns by selecting the create columns at click button on the left, make sure that theproperties of the columns have been set to the auto-select list. You may change the majoraxis direction by selecting Assign Frame/Lines Local Axis

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Add beams by selecting the create lines at click button on the left, make sure that the

properties of the beams have been set to the auto-select list.

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Add secondary beams by selecting the create secondary beams at click button on the left,you make change the number of secondary beams with each bay on the properties window.

To add the slab, select the Define -> Deck sections. Select Deck 1 and click on Modify.Change the type to solid slab and adjust the slab depth to 75mm

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Add slab by selecting the draw area button on the left, you make change the number ofsecondary beams with each bay on the properties window. Make sure that the properties ofthe slab have been set to Deck 1

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Before applying the load to the structure, one should create the load cases first, select thedefine static load case button on the top and define 3 types of loading, dead load, live load

and the cladding load. Click on the plan view and make sure that the similar stories buttonis on, select the slab and choose assign -> shell area loads -> uniform command. Selectthe dead load and change the dead load to 1.5kN/m 2 and click on OK. Replete for the

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the dead load and change the dead load to 1.5kN/m 2 and click on OK. Replete for the5kN/m 2 live load.

Select the perimeter beams and select the assign -> frame/line load -> distributed load to

assign the cladding loads.

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After adding all the loads to the structure, you may now click the run analysis button to start

your analysis.

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Example

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Example

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Example

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Example

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Example

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Example

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Example

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Example

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Example

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Part 12 Final

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