Ph.D. Thesis Defense Announcement

Time-Dependent Behavior of Pretensioned Stainless Steel Bars Used for Structural Rehabilitation and Retrofitting

by:
Falak Shah

Advisors:
Professors Abdul-Hamid Zureick (CEE) and Bruce Ellingwood (CEE)

Committee Members:
Professors Richard Neu (ME), Preet Singh (MSE),
and Phanish Suryanarayana (CEE)

Date & Time: Friday, October 31, 2014, at 11:00 a.m.

Location: SEB, Room 122

Abstract:
The objective of this study is to characterize the long-term behavior of an austenitic-ferritic stainless steel-based pretensioned system for strengthening reinforced concrete bridge pier caps in shear. Stress relaxation experiments were conducted on UNS S32101 stainless steel bars subjected to various initial stresses and temperatures within the low homologous temperature (LHT) regime. Data from these experiments were used to develop a viscoplastic constitutive model to describe the long-term time- and temperature-dependent behavior of the stainless steel bars. This mechanics-based approach is integrated with a new analytical method based on strut-and-tie analysis to compute the shear strength of reinforced concrete pier caps strengthened with this external pretensioned system. The findings of this investigation are used to form the basis for a technical guideline for the design of stainless steel-based pretensioned strengthening systems.