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Projects : CUREE-Kajima Joint Research Program
PHASE VI RESEARCH REPORT

CKVI-01: Simulating The Behavior of Steel Members Subject To Deterioration

Yuli Huang and Stephen Mahin (University of California, Berkeley)

Background
The work described in this report is part of the Phase VI CUREE/Kajima collaborative research project on factors leading to the progressive collapse of structures during earthquakes. Various types of nonlinear behavior are considered. These relate to material inelasticity, low cycle fatigue, and local and global geometric nonlinearities. The effects of sudden onset, quasi-brittle fracture are not considered herein. The class of structures serving as the focus of this work is steel braced frames. For such structures, the braces, columns, beams, and connections are subjected to significant axial loads, as well as bending moments and shear. Under these complexloading conditions, a wide variety of behavior mechanisms and failure modes can be postulated for each type member and connection. Thus, numerical models intended to assess the initiation and propagation of failure need to account for multi-axial states of material nonlinearity, local and global buckling, and the exhaustion of the ability of the material to deform inelastically due to the consequences of ultra low cycle fatigue.

As a part of these studies, component failures are modeled, focusing on physical theory (fiber) and finite element models. Compared to phenomenological models, these types of models require more computational effort, but incorporate more realistic physical representations of members and materials, including the initiation and evolution of damage through complete failure. In addition to examining the inelastic behavior and failure of traditional steel beam-to-column connections, members and connections in concentrically braced frames are emphasized due to the prevalence of global and local buckling. Beams, columns, braces and connections, and subassemblies comprised of these components are analyzed.

The overall scope of work includes:
1. Classification of Members and Behavior Models
2. Review and Evaluate Existing Computer Programs and Analytical Models
3. Develop and Validate Optimal Models
4. Evaluate Case Study Structures

The analytical procedures and numerical models considered are evaluated from four perspectives:
1. Predicting the onset of various failure modes (fracture initiation, onset of buckling, etc.);
2. Predicting the initiation and evolution of various types of material deterioration in individual members;
3. Computational effort; and
4. Ability to track propagation (sequence/evolution) of damage in determinant system under static and dynamic loads.

CONTENTS

Chapter 1: Analysis of Structural Component Failure focusing on Steel Structural Systems that Impose Significant Axial Loads in Members

- Background
- Objectives and Scope of Work

Chapter 2: Classification of Members and Behavior Models

- Overview
- Cataloging Experimental Data
- Conventional Brace Data
- Data on Gusset Plates
- Data on Subassembly Tests
- Data on Welded Steel Beam-to-Column Moment Connection
- Concluding Observations

Chapter 3: Review and Evaluate Software and Analytical Models for Simulating Component Behavior, including Deterioration and Failure

- Introduction
- Review of Available Computer Programs and Models
- Preliminary Evaluation of Computer Programs and Models
- Summary

Chapter 4: Systematic Evaluation and Improvement of Damage Material Models

- Introduction
- Review of Material Modeling for Structural Steel
- Formulation of a Cyclic Damaged Plasticity Material Model
- Interpretation and Calibration of Parameters
- Application of new Damaged Plasticity Model
- Summary

Chapter 5: Conclusions and Recommendations

Chapter 6: References

Appendix – User’s Manual for LS-DYNA MAT_153

File Download Type Size
CKVI-01 PDF 5.4 MB


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Consortium of Universities for Research in Earthquake Engineering
last updated 02.19.15