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Published byRussell Sanders Modified over 9 years ago
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Modeling Progressive Collapse by Plastic Analysis
Andrew Coughlin Ashutosh Srivastava Graduate Research Assistant Graduate Research Assistant The Pennsylvania State University The Pennsylvania State University Progressive Collapse Resistance Competition (PCRC) ASCE Structures Congress April 25, 2008 Vancouver, BC
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Images are public domain distributed by wikipedia.org
Motivation Images are public domain distributed by wikipedia.org
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Problem
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Dynamic Testing
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Static Testing
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Approach Cross Section Fiber Analysis XTRACTTM
Nonlinear Pushover Analysis CAPPTM Screenshots from XTRACTTM and CAPPTM, a collaborative effort between Imbsen and Associates and Charles Chadwell, Ph.D., P.E.
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Outline Assumptions Cross Sectional Fiber Analysis
Nonlinear Pushover Analysis Results Discussion
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Assumptions Similitude: 1/8 scale model Plastic hinge length d/2
1/8th all lengths 1/64th all forces Same stress Plastic hinge length d/2 Axial deflections not considered Fixed support conditions
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Outline Assumptions Cross Sectional Fiber Analysis
Nonlinear Pushover Analysis Results Discussion
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Cross Sectional Fiber Analysis
Material Models Cover Concrete Confined Concrete Reinforcing Steel Mander, J.B., Priestley, M. J. N., "Observed Stress-Strain Behavior of Confined Concrete", Journal of Structural Engineering, ASCE, Vol. 114, No. 8, August 1988, pp
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Cross Sectional Fiber Analysis
Cover concrete Beam at joint Column Reinforcing steel Beam at cutoff Roof beam Confined concrete XTRACTTM Screenshots from XTRACTTM, a collaborative effort between Imbsen and Associates and Charles Chadwell, Ph.D., P.E.
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Moment Curvature Screenshots from XTRACTTM, a collaborative effort between Imbsen and Associates and Charles Chadwell, Ph.D., P.E.
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Outline Assumptions Cross Sectional Fiber Analysis
Nonlinear Pushover Analysis Results Discussion
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Nonlinear Springs Screenshots from CAPPTM, a collaborative effort between Imbsen and Associates and Charles Chadwell, Ph.D., P.E.
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Model Elastic Beam Elements Nonlinear Hinges Where could they form?
Joints Load points Section changes (due to bar cutoff)
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Dynamic Test
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Static Test
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Plastic Hinge Formation
5 5 3 4 4 1 6 6 2 Plastic Hinge Formation
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Predicted Bar Fracture
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Predicted Bar Fracture Location
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Outline Assumptions Cross Sectional Fiber Analysis
Nonlinear Pushover Analysis Results Discussion
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Dynamic Results Structure did not collapse Max Deflection
Predicted = 0.96” Actual = 0.21” Permanent Deflection Predicted = 0.87” Actual = 0.20” Sources of Error Dynamic effects were not considered Large change in deflection for little change in load Material overstrength
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Static Results Maximum Load Displacement at bar fracture
Predicted = 1800 lb Actual = 1800 lb (before catenary action) Displacement at bar fracture Predicted = 3.9” Actual = 3.48”
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Actual Predicted
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Predicted Bar Fracture
Actual Bar Fracture Predicted Bar Fracture
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The rest of the story… Catenary Action Prediction Cutoff
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Outline Assumptions Cross Sectional Fiber Analysis
Nonlinear Pushover Analysis Results Discussion
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Acknowledgements Yang Thao of Imbsen and Associates
Educational Software Licenses Prof. Charles Chadwell, Cal Poly Modeling advice Prof. Jeffrey Laman, Penn State Review of submission Prof. Mehrdad Sasani, Northeastern Competition organization
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“And the structure stands…”
Questions? “And the structure stands…”
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