Experiment Program on Retrofitted Anchorage System under Impact Loads

Abstract

This study aims to evaluate the strength and performance of retrofitted anchorage system in concrete under impact loads. A novel technique called “Post Installation of Supplementary Anchorage” (PISA) is introduced to retrofit five different configurations of rebar anchorage system used in concrete. The configurations of rebar are straight bar (A1), 90 degree bend (A2),180 degree hook (A3), single head (A4) and double head (A5) bars which was retrofitted by supplementary steel reinforcement. Direct tension pullout loads are applied on 60 anchorage specimens (each 30 of conventional and retrofitted) casted with M25 grade concrete. The boundaries of tested specimens were followed by strut-and-tie analogy. The rebar anchorage tested at 1.58, 1.52 impact factor using two different bars of 12mm and 16mm diameter respectively. The deterministic characteristics of test parameters are normal strength, bond strength, ductility, and slip of anchorage at ultimate load. The test variables are rebar configuration, size of anchored bar, and presence of supplementary steel. The results validated by nonlinear finite element based ANSYS modeling. A good agreement of results between experiment and model analysis was observed. Also a considerable improvement of nonlinear characteristics of retrofitted anchorage such as ultimate load (3%-6%), bond strength (1%-6%), ductility (3%-4%), concrete contribution (20%-32%), bar slip (8%-48%) and crack width (30%-42%) was obtained. This study promotes useful information to retrofit non-engineered anchorage system by PISA technique. Application of this technique may further extended to retrofit discrete regions of concrete elements such as bracket connection, corbel projection and beam-column joint subjected to impact loads.