Team UCDSESM Yihai Bao, YeongAe Heo, Zhiyu Zong University of California, Davis April 4 th , 2008

1. Prediction for Progressive Collapse Resistance of a 2D RC frame Team UCDSESM Yihai Bao, YeongAe Heo, Zhiyu Zong University of California, Davis April 4th, 2008

2. Outline • Background • Methodology • the alternate path method by General Services Administration (GSA, revised June 2003) • nonlinear static, nonlinear dynamic • Models • Macroscopic modeling approach • Beam column modeling: beam-column fiber model • Joint modeling: macro joint model • Results • Dynamic response after removing first floor center column • Response from static pushdown • Summary

3. Background Glass Column Testing frame at Northeastern University

4. Methodology: GSA Criterion GSA criterion utilizes the alternate path method to ensure that progressive collapse does not occur • Scenario: instantaneous removal of a column in the first story • Structural analysis for prescribed set of load combinations and material strength factors • Linear/Nonlinear Static • Nonlinear Dynamic • Evaluating the potential for progressive collapse • Strength requirements (DCR, Demand Capacity Ratio) • Reinforcement detailing and ductility requirements

5. Methodology: Two Step Test • First step • Dynamic loading: breaking the glass column with sudden impact • Second step • Static loading: displacement controlled pull down if frame dose not collapse during first step Testing frame with dynamic loading Northeastern University Testing frame under pull down loading Northeastern University

6. Models: Macroscopic Modeling Macroscopic modeling approach • Using simplified models to predict a specific overall behavior Advantages: computational efficiency; compatibility with traditional structural analysis models. Disadvantages: complexities involved in development of an objective and transparent calibration procedures. Finite element model Macro joint model Beam fiber model

7. Models: Materials Panel Shear Spring Property Reference: Vecchio & Collins (1986) Concrete Property Reference: Mander et al (1988) Interface Shear Spring Property Reference: Walraven (1981) Bond-Slip Property Reference: Lowes & Altoontash (2003)

8. Bond-Slip Table: Average bond strengths as a function of steel stress state For With, For With, and Bond and bar stress distribution for a reinforcing bar anchored in a joint From Lowes, L.N. & Altoontash, A. (2003) PEER Report

9. Interface shear Walraven J.C. (1981)

10. Results Observed position of first bar fracture Predicted position, “top bar”, of first barfracture

11. Summary • Both simulation results and test results show the frame dose not collapse and no wire fractures after removal of first floor center column. • Simulation results and test results indicate the same location of first wire fracture which is close to steel cutting region in second floor middle bay beams. • No shear failure (joint shear failure or beam shear failure) is observed. • Simulation responses give a good prediction for the tested frame although minor disparity exists.

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