ATC-114 Next-Generation Hysteretic Relationships for Performance-based Modeling and Analysis

Nonlinear analysis has become an increasingly useful and important tool for evaluation, upgrade and design of structures for seismic resistance. However, despite steady improvements in analysis capability, most practice remains anchored to guidelines developed more than 20 years ago. Under its ATC- 114 project, the Applied Technology Council is developing updated hysteretic envelope models for use in seismic analysis of new and existing buildings. The intent of this project is to support the development of updated building code criteria contained in such standards as ASCE 7 and ASCE 41. Project support is provided by the National Institute of Standards and Technology

A cyclic backbone curve for squat reinforced concrete shear walls

by Siamak Epackachi, Nikhil Sharma, Andrew Whitaker, Ronald O. Hamburger and Ayse Hortacs

A cyclic backbone curve for shear-critical reinforced concrete walls

Backbone curves are used in seismic design standards as the basis for developing component models for nonlinear static and dynamic analysis. Herein, data from 240 tests of rectangular, barbell, and flanged shear-critical walls are assembled and analyzed to develop an improved cyclic backbone curve for use in nonlinear response-history analysis. Values of drift ratio and normalized lateral force at the control points on the cyclic backbone curve are identified. The effects of design parameters, including wall aspect ratio, axial load, day-of-test concrete compressive strength, vertical and horizontal web reinforcement ratio, reinforcement ratio in the boundary elements, and yield strength of reinforcement, on the coordinates of the control points are addressed. The accuracy of equations for peak shear strength is assessed using the collected test data.by Siamak Epackachi, Nikhil Sharma, Andrew Whittaker, Ronald O. Hamburger and Ayse Hortacs