ce710 – behavior and numerical modeling of rc … documents (do not need to be purchased) • k....

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CE710 – Behavior and Numerical Modeling of RC Structures

Instructor: Dan Kuchma, GC B2 474, [email protected]: Fabio Brantschen, GC B2 485, [email protected]

Learning Objectives1.) Develop an in-depth understanding of the behavior of structural concrete 2.) Be able to safely and effectively use a variety of computational tools for the design and analysis of concrete structures

Reference Documents (do not need to be purchased)• K. Maekawa, A. Pimanmas, and H. Okamura, “Nonlinear Mechanics of Reinforced Concrete”• fib Task Group 4.4 Computer Based Modeling and Design, “Practitioners' Guide to Finite Element Modelling of Reinforced Concrete Structures”, International Federation for Structural Concrete (fib), State-of-the-Art Report, Bulletin 45, 344 pp., 2008• http://www.civ.utoronto.ca/vector/journal_publications.html (jp1.pdf, jp2.pdf, jp4.pdf, jp6.pdf, jp8.pdf, jp9.pdf, jp12.pdf, & jp42.pdf) mandatory reading

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PhD University of Toronto 1996 under Michael Collins Started as an Assistant Professor at the University of Illinois 1997 Currently an Associate Professor at the University of Illinois Chair of ACI Technical Committee 445 “Shear and Torsion” Member of ACI318 Subcommittee on “Shear and Torsion” Introduced 2 Shear Design Methods in AASHTO LRFD Specifications Member of 3 Groups of the Int. Federation of Structural Concrete (fib) Director of Operations of Illinois NEES Testing Facility Consultant on 14 Projects; P-Eng: Province of Ontario Teaching Experiences: All RC & PC Concrete Courses, Statics,

Introduction to Design, Structural Dynamics, Structural Experimentation

Research Interests: Shear, Torsion, Strut-and-Tie Models, Advanced Instrumentation, Large-Scale and Fully-Realistic Experimentation, Data Visualization and Analysis, Earthquake Engineering

My Background

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Syllabus – Course Program

Week # Date Course Topic Tutorial Content1 21-Sep (0) Course Introduction Matlab Instructions

(1) Compressive Response: Columns Asmt. #1 Distributed (Q&A)2 28-Sep (1) Compressive Response: Columns, cont. Matlab Interfaces

Asmt. #1 Due; Asmt. #2 Distributed (Q&A)3 5-Oct (1) Compressive Response: Walls In-Class Exercise on Testing of Columns

Asmt. #2 Q&A4 12-Oct (2) Tensile Response Asmt. #2 Due; Asmt. #3 Distributed (Q&A)5 19-Oct (3) Response of Membrane Elements Asmt. #3 Q&A6 26-Oct (3) Response of Membrane Elements, cont. Asmt. #3 Q&A7 2-Nov (4) 2D Continuum FEA Tools Asmt. #3 Due; Asmt. #4 Distributed (Q&A)8 9-Nov (5) Experimental Measurements and Analysis Asmt. #4 Q&A

Discussion of Project Options9 16-Nov (6) Model Validation Asmt. #4 Due

Model Validation In-Class Exercise11 30-Nov (8) Bond To Be Determined12 7-Dec (9) Beams with Shear To Be Determined13 14-Dec Test Test Only on This Day14 21-Dec Project Presentations Presentations Only on This Day

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Syllabus – Overview of Course Content

(1) COMPRESSIVE RESPONSE OF STRUCTURAL CONCRETE 1.1 Unreinforced Concrete 1.2 Actively Confined Plain Concrete 1.3 Circular Concrete Columns Passively Confined by Spirals 1.4 Rectangular Concrete Columns Passively Confined by Hoops/Ties 1.5 ACI318 Design Requirements for Columns 1.6 Constitutive Models for Passively Confined Concrete Columns ------------------------------------------------------------------------------------------------------- 1.7 Walls (including Webs/Membranes) Subjected to Transverse In-Plane Compression 1.8 Walls Subjected to Transverse Tension In-Plane Tension 1.9 Walls Confined by Out-Of-Plane Reinforcement 1.10 Constitutive Models for Walls (incl.Webs/Membranes) (2) TENSILE RESPONSE OF STRUCTURAL CONCRETE 2.1 Cracking Strength 2.2 Average Tensile Stress in Concrete 2.3 Crack Widths and Crack Spacings 2.4 Force Transfer across Cracks

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Syllabus – Overview of Course Content

(3) RESPONSE OF 2D CONTINUUMS 3.0 Response of Membrane Elements 3.1 Variable Angle Truss Model 3.2 Compression Field Theory (CFT) 3.3 Example: Shear Response by CFT 3.4 Modified Compression Field Theory (MCFT) 3.5 Secant Stiffness Formulation for MCFT 3.6 Program MEMBRANE 2000 (M2K) 3.7 Analysis of 2D continuums

(4) 2D CONTINUUM FEA TOOLS (5) EXPERIMENTAL MEASUREMENTS AND ANALYSIS (6) MODEL VALIDATION (7) FRACTURE (8) BOND (9) BEAMS WITH SHEAR STUDENT PROJECT PRESENTATIONS

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Syllabus – Topic 1

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Syllabus – Topics 2-3

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Syllabus – Assignments and Projects

Assignments (in Matlab) (1) Predicting the Response of a Linear Elastic Simply-Supported Beam using Matlab (2) Fiber (or Multilayer) Analysis of a Section Subjected to Flexural and Axial Loads (3) Predicting the Inelastic Response of a Reinforced Concrete Frame (4) Predicting the Response of a 2D Element Subjected to Membrane Actions Project Ideas 1.) Group Project on Model Evaluation/Validation 2.) Extension of Assignments 3.) Develop Non-Linear 2D Continuum Analysis Program 4.) Develop Sectional Analysis Program with Shear Included 5.) Understanding and Implementation of Other Models 6.) Understand Functionality of a particular Software 7.) Other, as proposed by students Distribution and Posting of Materials http://ibeton.epfl.ch/Etudiant/et_doct-11/default.asp (then go to “Course Lectures Link”)

Assignments– #1 Response of Linear Elastic Beam

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Assignments– #2 Moment-Curvature Response of a Section

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Assignments– #3 Inelastic Response of a Frame

Provided Working Matlab Program for Linear Elastic Frame Analysis Complete with GUI for Plotting Shear and Bending Moment Diagrams Will Need to Utilize Non-Linear Beam Analysis Program that you

Developed in Assignment #2 to Predict Full Inelastic Response Simple Secant Formulation is to be used

3”

3”

17”

10”

(4)#9Bars

(4)#9Bars

5’ 5’ 10’

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Assignments– #4 Response of a Membrane Element

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Project Example – 2D Continuum Analysis

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Project Example – 2D Continuum AnalysisSet Load Step

dVBDBT

MCFT

Bilinear Quadrilaterals (Q4)

Isoparametric formulation

Any shaped quadrilateral

Gauss Quadrature numerical integration

Full Order Integration (2nd order)

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Project Example – 2D Continuum Analysis

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Project Example – Response of Beam to Shear & Moment

16

50

02

00

30

0

60

0

35050 900 400

150 150

P

Project Example – Model Validation

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18


19


20

0

200

400

600

800

1000

0 2 4 6 8 10 12 14

Displacement, mm

Fo

rce,

kN

Experiment VecTor Rotating Crack Maekawa CAST


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22


23

Capacity

DemandF.S.

Design Code

Linear Elastic Analysis

>

Lo

ad/S

tres

s

Deformation/Strain

Axial load

Moment

Torsion

Shear

Problem Statement – Shortcomings in Design Practice

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Concrete structures are not linear elastic


-300

-200

-100

0

100

200

300

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

Base Shear (kips)

Top Drift (%)

W

Elastic Stiffness

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Codes-of-practice use one size fits all empirical expressions


0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 20 40 60 80 100 120 140

f'c (MPa)

Vte

st / V

AC

I

0.0

1.0

2.0

3.0

0 20 40 60 80 100 120 140f′c (MPa)

bdfV ccode '17.0

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Laboratory structures not representative of field structures


Shear Test, Illinois, circa 1910

Confederation Bridge, Canada

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Codes do not cover many of the most critical aspects of design

Codes are principally concerned with strength


-50

-40-34

-36-39 -27

-35 -35 -32

-46-30

-40-33

-34-34

-35

-36

-28-22

-31 -28-27

-24

-50

-40-34

-36-39 -27

-35 -35 -32

-46-30

-40-33

-34-34

-35

-36

-28-22

-31 -28-27

-24

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Increasing complexity of codes


ACI Code > 40 Equations for Shear Design

AASHTO LRFD Specifications 1822 Pages

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Increasing complexity of codes Difficult to account for advancements in

materials, structural forms, and analysis methods in codes of practice


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Integrated linear elastic analysis and design computer programs


Linear Elastic Analysis + Implementation of Codes =

Str. Eng. too reliant on software

+ automated design procedure

+ uncertain dist. of responsibility

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Integrated linear elastic analysis and design computer programs

Non-uniqueness of adv. analysis tools


Deformation/Strain

Load

/Str

ess

A

B

C

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Motivation – Support the Advancement of Eng. Practice

Principally Linear Elastic Analysis & Empirical Code Provisions

Integrated Design &Advanced Analysis

Environment

New MaterialsNew Design ConceptsEngineering Creativity

PRESENT

FUTUREPerformance-BasedDesign; Improved Limit State Definitions, Infrastructure Mgmt.

Data from Experiments

Comprehensive Test Data

Benchmark Tests

System Level Simulations

On-Line Data Archives

Model Validation (New Field)

Data Visualization/Analysis Tools

Challenges for Data Fusion

Metrics for Model Validation

Probabilistic-Based Approaches

Instruction (Needed Additions)

Behavior incl. Laboratory-Based

Advanced Models & Comp. Tools

Technical Organizations

Peer-Reviewed Test Data

Support Use of Comp. Tools

Tim

elin

e: 0

-40

Yea

rs

Comp. Tools with Known Accuracy

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Motivation – Building Information Modeling

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Capabilities of advanced computational tools will continue to increase Development of design tools in absence of consideration of known and

definable complexities is both limiting and potentially dangerous Building Information Modeling (BIM) Tools are here to stay and will

continue to develop Existence of BIM makes automated numerical modeling, design

checking, performance evaluation, and design iterations, etc. possible To support the development and use of advanced computational tools,

the following is needed Changes in research that take advantage of increasing capabilities

of advancing sensor technologies Creation of model validation methods and metrics Changes in structure of codes-of-practice Changes in education are needed that allow students/practitioners

to gain an improved understanding of behavior and of how to safe users on advanced computations tools

Motivation – Certainties

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Future Design Practice for Civil Structures

Designer

Archived data

Data-Visualization

Model-Validation