Title:
Experimental Evaluation of Prestressed Concrete Girders with Low-shear Reinforcement
Author(s):
Nikhil Potnuru
Publication:
Web Session
Volume:
ws_F24_NikhilPotnuru.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
11/3/2024
Abstract:
This study experimentally investigates minimum shear reinforcement requirements based on existing codes of practice and a parametric study of the factors affecting them. Minimum shear reinforcement requirements in the American Association of State Highway Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications were originally based on tests conducted on reinforced concrete panels and beams as well as limited, recent data on prestressed girders. Thus, it remains unclear if current provisions provide sufficiency or over-conservatism in shear design. An experimental study was conducted on 11 full-scale precast, pretensioned bridge girder specimens with a four-point bending test setup. The experimental specimens were designed following a study of the extent of the minimum shear reinforcement zone in typical girder designs. The specimens have variations in design parameters that are known to affect minimum shear reinforcement requirements, such as cross-section depth, shear span-to-depth ratio, concrete tensile strength, prestressing ratio, tendon path, shear reinforcement spacing, and yield strength. The experimental tests featured sensor arrays such as strain gauges, LVDTs, and string potentiometers, as well as advanced optical data acquisition methods including Digital Image Correlation (DIC) and the Optotrak system. The performance of these girders was evaluated in terms of Reserved Shear Strength (RSS) index, which is the ratio of the nominal shear strength to the shear strength at the onset of web shear cracking, and serviceability requirements. The experimental findings are compared with provisions in codes and standards and, together with a companion study, make recommendations for new minimum shear requirements.