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51 1 304-1-CSEP E21 Lecture 6 3D Elastic Analysis

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Instructor: Ella Li
CSE E21 - 2022
CSE E21 Two Way Slab
Lecture 6
3-D Elastic Analysis
Course Coordinator:
John Pao, P.Eng. Struct.Eng., S.E.
Instructor:
Ella Li, MASc, P.Eng, PE, SE
Certificate Program in Structural Engineering – E21
Instructor: Ella Li
LESSON OVERVIEW
1) FINITE ELEMENT ANALYSIS
2) ADAPT-BUILDER
~D
3) MOMENT REDISTRIBUTION
Certificate Program in Structural Engineering – E21
SAFE
RAM
CONCEPT
.
No. 2
Instructor: Ella Li
1) FINITE ELEMENT ANALYSIS
• 1.1 INTRODUCTION
↑β‘£
• 1.2 ADAPT-BUILDER
• 1.3 SAFE
• 1.4 RAM CONCEPT
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these are
Certificate Program in Structural Engineering – E21
Adapt
FEM
RC
.
Uses
ELF
.
No. 3
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
WHAT IS FE AND WHY
•
•
•
•
Finite element analysis is a powerful computer method of analysis that can be used to
obtain solutions to a wide range of one- two- and three-dimensional structural
problems involving the use of ordinary or partial differential equations.
For the majority of structural applications the displacement FE method is used, where
displacements are treated as unknown variables to be solved by a series of algebraic
equations. Each member within the structure to be analyzed is broken into elements
that have a finite size.
For a 2D surface such as a flat slab, these elements are either triangular or
quadrilateral and are connected at nodes, which generally occur at the corners of the
elements, thus creating a ‘mesh’.
Parameters and analytical functions describe the behavior of each element and are
then used to generate a set of algebraic equations describing the displacements at
each node, which can then be solved. The elements have a finite size and therefore
the solution to these equations is approximate; the smaller the element the closer the
approximation is to the true solution.
Certificate Program in Structural Engineering – E21
No. 4
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
WHAT IS FE AND WHY
•
•
•
•
FE methods generate numerous complex equations that are too complicated to be
solved by hand; hence FE analysis was of interest only to academics and
mathematicians until computers became available in the 1950s.
The relative cost of computer hardware and software has reduced significantly over
recent years and many engineers now have access to powerful software such as finite
element (FE) analysis packages.
it needs to be understood that FE is an elastic method, just like the elastic frame
method described in the Codes.
The use of FE analysis and design is certain to increase in the future. Currently it is a
very useful method for slabs with irregular geometry, for dealing with openings in the
slab and for estimating deflections. However, it is important to realize that the
technique will not give lower design bending moments for regular grids.
Certificate Program in Structural Engineering – E21
No. 5
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
FINITE ELEMENT ANALYSIS ADVANTAGES
•
•
•
•
•
•
It assists in the design of slabs with complex geometry where other methods require
conservative assumptions to be made.
It can be used to assess the forces around large openings.
It can be used to estimate deflections where other methods are time-consuming,
particularly for complex geometry.
It can be used for unusual loading conditions, e.g. transfer slabs.
The model can be updated should changes occur to the design of the structure.
Computer processing speeds are increasing; reducing the time for analysis
Certificate Program in Structural Engineering – E21
No. 6
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
FINITE ELEMENT ANALYSIS DISADVANTAGES
•
•
•
•
•
•
The model can take time to set-up, although the latest generation of software has
speeded up this process considerably.
The redistribution of moments is not easily achieved.
There is a steep learning curve for new users and the modelling assumptions must
be understood.
Human errors can occur when creating the model; these can be difficult to locate
during checking.
Design using FE requires engineering judgement and a feel for the behavior of
concrete.
FE will not always return lower bending moments and deflections than would be
obtained using traditional methods.
Certificate Program in Structural Engineering – E21
No. 7
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
FE SOLVERS – LINEAR ANALYSIS
•
•
•
•
This is currently the most widely used method of FE analysis, but it is less sophisticated
than non-linear analysis.
Reinforced concrete (RC) is treated as an elastic isotropic material, which it evidently is
not, and a number of assumptions have to be made to allow this method to be used.
These assumptions in the modelling can lead to misunderstanding of the results.
A linear analysis is more than adequate for carrying out a design at the ultimate limit
state. The serviceability limit state can be checked by using ‘deemed to satisfy’ span-toeffective-depth ratios or by using conservative values for the elastic modulus and slab
stiffness.
Typically, 85% of elements are designed using the span-to-effective-depth rules and this
is considered to be perfectly adequate for the majority of designs. Even the most
sophisticated analysis only giveS an estimate of deflection in the range +15% to –30% .
Certificate Program in Structural Engineering – E21
No. 8
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
FE SOLVERS – NON-LINEAR ANALYSIS
•
•
•
Many FE packages are capable of carrying out non-linear (iterative) analysis, but this
is useful only for reinforced concrete design where it can be used to model the cracked
behavior of concrete.
Non-linear analysis is used for RC design because as the slab is loaded it will crack
and this affects its stiffness. The program carries out an analysis with uncracked
section properties; it can then calculate where the slab has cracked, adjust the
material properties and run the analysis again. This process continues until the
variation in section properties between runs reaches a predetermined tolerance.
A more sophisticated method is to also model the yielding of the reinforcement where
it reaches the elastic limit. This requires advanced software and is generally used only
for specialist situations.
I
For
gravity
design
βœ— 10
,
analysis
Reboot
stops @
cracked
section
yielding
Certificate Program in Structural Engineering – E21
No. 9
Instructor: Ella Li
1.1 FINITE ELEMENT ANALYSIS - INTRODUCTION
FE SOLVERS – NON-LINEAR ANALYSIS
•
•
•
non-linear software will carry out an iterative analysis to determine an initial deflection;
this will be based on initial, assumed, areas of reinforcement.
Once the initial deflection has been determined, an assessment of the results should
be carried out to decide whether the initial areas of reinforcement were appropriate. If
not, they should be revised and the analysis re-run until there is convergence. It will be
necessary to run the ULS model again with the correct reinforcement, because varying
the area of reinforcement will alter the slab stiffness and hence the distribution of the
moments (i.e. the stiffness at the supports will be reduced because of cracking and
hence moment will be shed to other areas).
An important aspect to achieving a realistic estimate of deflection is to consider the
loading history for the slab; once the slab has cracked (and hence has reduced in
stiffness) this will affect the deflection throughout the life of the slab. This should be
considered in the model.
Certificate Program in Structural Engineering – E21
No. 10
Instructor: Ella Li
1.2 FINITE ELEMENT ANALYSIS – ADAPT BUILDER
ADAPT BY RISA
https://risa.com/product
s/adapt-builder
•
•
•
•
1
FOR
FEM
.
FULLY INTEGRATED DESIGN FOR CONCRETE BUILDINGS.
Seamless Modeling Workflow for Every Concrete Building.
Efficiently analyze slabs or entire structures for the combined effects of gravity, lateral
and vibration loading, utilizing true 3D finite element analysis, straightforward load
takedown and realistic slab alignment.
Whether you’re investigating an existing reinforced concrete slab or designing a multistory post-tensioned building, ADAPT-Builder allows you to control all aspects of design
including cracking, long term deflections and punching shear, ensuring results are
accurate and complete.
Certificate Program in Structural Engineering – E21
No. 11
Instructor: Ella Li
1.2 FINITE ELEMENT ANALYSIS – ADAPT BUILDER
ADAPT BUILDER OUTPUT
Certificate Program in Structural Engineering – E21
No. 12
Instructor: Ella Li
1.3 FINITE ELEMENT ANALYSIS - SAFE
SAFE BY CSI
https://www.csiamerica.com/
products/safe
•
•
•
•
•
ANALYSIS AND DESIGN OF FLOOR SYSTEMS
SAFE offers a single user interface to perform modeling, analysis, design and reporting.
A new model explorer is available for quick access to objects, properties and forms.
CSI solvers have been tried and tested by the industry for over 45 years. The SAPFire
Analysis Engine can support multiple 64-bit solvers for analysis optimization and can
perform both eigen analysis and Ritz analysis.
SAFE is ideal for modeling foundations, basemats, and footings. Easily model soil
supports and zero tension soil models with uplift analysis.
Design strips are used to define how reinforcement requirements are to be calculated.
SAFE can automatically define the strips for you, or you can define them yourself.
Certificate Program in Structural Engineering – E21
No. 13
Instructor: Ella Li
1.3 FINITE ELEMENT ANALYSIS - SAFE
SAFE OUTPUT
might
not
good
be
M
¥¥¥¥%N
↓
term
short
OK !
Is
cracked
is
good
.
deflection
Certificate Program in Structural Engineering – E21
No. 14
Instructor: Ella Li
1.4 FINITE ELEMENT ANALYSIS – RAM CONCEPT
RAM CONCEPT BY BENTLEY
https://www.bentley.com/soft
ware/ram-concept/
•
•
•
•
•
THE GO-TO FOR CONCRETE SLAB AND FOUNDATION DESIGN
Optimize the design of post-tensioning, reinforcement, and studded shear reinforcement
for post-tensioned concrete floors using cloud-based optimization. Save engineering time
by letting the optimizer sort through thousands of design alternatives and have
confidence that your post-tensioned design has reduced material and labor costs.
Design Raft Or Mat Foundations using soil springs and a zero-tension analysis.
Confidently complete your designs with the extensive support of international standards.
Design And Analyze With Finite Elements. Complete building analysis, design, drafting
with finite element analysis. Reduce time spent waiting for results with fast solvers.
Analyze Deflections For Time-Dependent Effects
Certificate Program in Structural Engineering – E21
No. 15
Instructor: Ella Li
1.4 FINITE ELEMENT ANALYSIS – RAM CONCEPT
RAM CONCEPT OUTPUT
Certificate Program in Structural Engineering – E21
No. 16
Instructor: Ella Li
2) ADAPT BUILDER
• 2.0 SOFTWARE INSTALLATION
• 2.1 GEOMETRY
using
• 2.2 MODEL SETUP
Eg
• 2.3 LOADS
.
known
Use
DDM
check
Example
.
and
with
software
• 2.4 MODELING
• 2.5 ANALYTICAL TOOLS
• 2.6 DESIGN OUTPUT
Certificate Program in Structural Engineering – E21
No. 17
Instructor: Ella Li
2.0 ADAPT BUILDER - SOFTWARE INSTALLATION
LICENSE FOR SEABC E21 PARTICIPANTS
•
Software download: https://secure.risa.com/index/downloads
Register for ADAPT-Builder License
Certificate Program in Structural Engineering – E21
RISA Customer Portal
No. 18
Instructor: Ella Li
2.0 ADAPT BUILDER - SOFTWARE INSTALLATION
INSTALLATION
Licensing Type
Certificate Program in Structural Engineering – E21
First Time Launch Software
No. 19
Instructor: Ella Li
2.0 ADAPT BUILDER - SOFTWARE INSTALLATION
LAUNCH SOFTWARE
7.
PP0R
RC
design
.
Launch Software
Certificate Program in Structural Engineering – E21
No. 20
Instructor: Ella Li
2.0 ADAPT BUILDER - SOFTWARE INSTALLATION
RESOURCES
User Manual
https://risa.com/risahelp/adaptbuilder/index.html#
Home.htm?TocPath=_____1
Slab Design Tutorial
https://risa.com/risahelp/adaptbuilder/Content/Tuto
rials/ADAPT-Builder%20MultiLevel%20Tutorial_05052022.pdf
https://risa.com/risahelp/adaptbuilder/index.html#T
utorials/ADAPT-Builder%20Multi-Level-Tutorial.zip
YouTubeTutorial
https://www.youtube.com/playlist?list=PLYrSU5MZrOnRu0XwKUlY0JR1hGS_P1ez
Certificate Program in Structural Engineering – E21
No. 21
Instructor: Ella Li
2.0 ADAPT BUILDER – SOFTWARE INSTALLATION
MAIN USER INTERFACE
1.
2.
3.
4.
5.
6.
7.
Certificate Program in Structural Engineering – E21
Quick Access
(toolbar)
Level Tools (toolbar)
Message Bar
Quick Access Tools
(toolbar)
Status Bar - Model
Information
Results View (Result
Display Viewer panel)
Properties/Colorize/
Visibility (panels)
No. 22
Instructor: Ella Li
2.1 ADAPT BUILDER – STRUCTURE GEOMETRY
CONCRETE HANDBOOK EXAMPLE
•
EXAMPLE MODIFIED FROM CAC CONCRETE HANDBOOK
Example
¥1
"
Certificate Program in Structural Engineering – E21
No. 23
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
GEOMETRY
•
Method #1 Creating Gridlines: two options for creating gridlines.
– Using the Wizard
– Creating User-Defined gridlines.
•
Method #2 Import CAD File
Certificate Program in Structural Engineering – E21
No. 24
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
REFERENCE PLANE
By default, a new file in ADAPT-Builder has three reference planes:
• Bottom Plane
• Current Plane
• Top Plane.
µ
"
:*
:*
or
"
µ
Certificate Program in Structural Engineering – E21
No. 25
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
MATERIAL PROPERTIES - CONCRETE
•
•
software
gives
Compressive strength fc’ = 25 MPa
you default
Modulus of Elasticity (CSA A23.3-14 CL. 8.6.2.2) (Eq. 8.3)
γ𝑐 1.5
2300
= 3300 25 + 6900 ×
2400 1.5
2300
va↳
only
•
𝐸𝑐 = 3300 𝑓𝑐′ + 6900 ×
•
Modulus of Rapture of Concrete (CSA A23.3-14 CL. 8.6.4) (Eq. 8.3)
•
π‘“π‘Ÿ = 0.6λ 𝑓𝑐′ = 0.6 × 1.0 × 25 = 3.0 π‘€π‘ƒπ‘Ž
Certificate Program in Structural Engineering – E21
.
= 24,943 π‘€π‘ƒπ‘Ž
No. 26
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
MATERIAL PROPERTIES - REINFORCEMENT
•
Specified yield strength of the reinforcement fy = 400 MPa
Certificate Program in Structural Engineering – E21
No. 27
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
DESIGN CRITERIA
•
Design code: CSA A23.3-14
-
check
all
tubs
•÷:;;÷÷÷
more
•
tower
!¥m
or
Certificate Program in Structural Engineering – E21
No. 28
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
DESIGN CRITERIA
\
Certificate Program in Structural Engineering – E21
No. 29
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
DESIGN CRITERIA
Certificate Program in Structural Engineering – E21
No. 30
Instructor: Ella Li
2.2 ADAPT BUILDER – MODEL SETUP
DESIGN CRITERIA
Certificate Program in Structural Engineering – E21
No. 31
Instructor: Ella Li
2.3 ADAPT BUILDER – LOADS
LOAD CASE AND LOAD COMBINATION
Certificate Program in Structural Engineering – E21
No. 32
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MODELING SLAB
-0
I
the
corner
should
the
OR
Draw
not
@ Gt
change
coordinate
first
CAD
in
Certificate Program in Structural Engineering – E21
No. 33
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MODELING COLUMN
:÷ :O
above
& below
.
@ properties
↑
You
thou
Id
"
have
COLUM
2#
type
You
•
not
¥0m
• ment
.
Do
Not
to
Certificate Program in Structural Engineering – E21
use
MY
Rotate
COLUMNS
No. 34
°
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MODELING COLUMN – COPYING VERTICALLY
bottom
top @
of
Certificate Program in Structural Engineering – E21
Stato
No. 35
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MODELING METHOD – IMPORT CAD/DXF
•
•
STEP 1: Go to File → Import → DWG
STEP 2: Transforming DWG Entities into ADAPT-Builder Model Objects
Certificate Program in Structural Engineering – E21
No. 36
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
TOP FRONT VIEW
Certificate Program in Structural Engineering – E21
No. 37
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
VERIFY MATERIAL PROPERTIES
colour
coded
material
properties
Certificate Program in Structural Engineering – E21
No. 38
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
ESTABLISH COMPONENT CONNECTIVITY TOOL
relative
;¥hmnthat
¥
to
me
µpets
.
In:{
Certificate Program in Structural Engineering – E21
No. 39
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MESHING THE MODEL
Certificate Program in Structural Engineering – E21
No. 40
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
ANALYZING THE MODEL
check
deflected
Shape
check moment diagrams
check Reaction
@ column
Certificate Program in Structural Engineering – E21
.
No. 41
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MODEL VERIFYING - SLAB DEFORMATION (SELF-WEIGHT)
chelK#
:É↑"
¥we
deported
shape
Certificate Program in Structural Engineering – E21
No. 42
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
MODEL VERIFYING - SLAB DEFORMATION (SELF-WEIGHT)
•
CHECK COLUMN AT GRIDLINE D&3:
𝑃 = 24 × 0.25π‘š × 6.6π‘š × 6.7π‘š + 12.71 = 278.0 π‘˜π‘
c.net#J
:*
:::
*important
Weight of
column
column
..
toe
stiffness
Certificate Program in Structural Engineering – E21
No. 43
Instructor: Ella Li
2.4 ADAPT BUILDER – MODELING
APPLY GRAVITY LOAD TO THE MODEL
•
SLAB UNIFORM LOAD
– Superimposed Dead Load SDL = 1.0 kN/m2
– Live Load LL = 1.9 kN/m2 for Residential Floors
•
CLADING LINE LOAD
must
the
select
before
slab
How
?
,↓Y¥%ed
Certificate Program in Structural Engineering – E21
No. 44
Instructor: Ella Li
2.5 ADAPT BUILDER – ANALYTICAL TOOLS
SUPPORT LINES AND SPLITTERS
•
•
•
≤
design strip
.
better
manage
If you'd like to hasten the design process in ADAPT-Builder, each slab must be subdivided into multiple design strips associated with a specific design criterion; (two-way
slab, one-way slab, or beam) for two characteristic directions of the slab, X and Y (these
directions do not have to align with the global X and Y axes).
These strips are further sub-divided into design sections for the purpose of finding design
actions, stresses, reinforcement, and more. You have complete flexibility and control over
the location of design strips and the density and distribution of design sections.
Splitters can be used in conjunction with support lines to give the user more control over
the tributary generated by the program. Refer to the Splitters topic for more information
on using splitters to limit the tributary width of the support line tributary.
Learn
main advantage
0g ADAPT
↓:[Ignores.→:÷:*:*
over SAFE
fine
Certificate Program in Structural Engineering – E21
No. 45
Instructor: Ella Li
2.5 ADAPT BUILDER – ANALYTICAL TOOLS
SUPPORT LINES
L_4aLUMNSTR
↳
steb
create
step
support lines
How
≤ Advantage
ADAPT
to
edit
suppot
line
9
.
0
:*
.
support
""
lines
are
4h ships
.
//
qq.eyj-my .IT#IIpp0rts
:*
÷
.
live
¥
:*
short
Certificate Program in Structural Engineering – E21
No. 46
Instructor: Ella Li
2.5 ADAPT BUILDER – ANALYTICAL TOOLS
MIDDLE STRIP
?
↳ what is this
the support
points
↳ divide
in
further
µm%%α΅—emidβ‘ 
to create
middle
strip
Certificate Program in Structural Engineering – E21
No. 47
Instructor: Ella Li
2.5 ADAPT BUILDER – ANALYTICAL TOOLS
DESIGN STRIP
Certificate Program in Structural Engineering – E21
No. 48
Instructor: Ella Li
2.5 ADAPT BUILDER – ANALYTICAL TOOLS
ANALYZE THE SLAB
Certificate Program in Structural Engineering – E21
No. 49
Instructor: Ella Li
2.6 ADAPT BUILDER – DESIGN OUTPUT
MOMENT CAPACITIES
STEP
Certificate Program in Structural Engineering – E21
#1
No. 50
Instructor: Ella Li
2.6 ADAPT BUILDER – DESIGN OUTPUT
MOMENT CAPACITIES
Certificate Program in Structural Engineering – E21
No. 51
Instructor: Ella Li
2.6 ADAPT BUILDER – DESIGN OUTPUT
MOMENT CAPACITIES – MOMENT DEMAND
Certificate Program in Structural Engineering – E21
No. 52
Instructor: Ella Li
2.6 ADAPT BUILDER – DESIGN OUTPUT
MOMENT CAPACITIES – COMPARISON WITH EFM
Certificate Program in Structural Engineering – E21
No. 53
Instructor: Ella Li
3) MOMENT REDISTRIBUTION
• 3.1 CODE OVERVIEW
Certificate Program in Structural Engineering – E21
No. 54
Instructor: Ella Li
3.1 MOMENT REDISTRIBUTION – CODE OVERVIEW
CSA A23.3-14
Certificate Program in Structural Engineering – E21
No. 55
Instructor: Ella Li
3.1 MOMENT REDISTRIBUTION – CODE OVERVIEW
CONCRETE DESIGN HANDBOOK
Certificate Program in Structural Engineering – E21
No. 56
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