Experimental study of repaired RC columns subjected to uniaxial and biaxial horizontal loading and variable axial load with longitudinal reinforcement welded steel bars solutions

Abstract

A B S T R A C TThe study of the reinforced concrete (RC) columns' response to horizontal cyclic loads is of full importance to understand how earthquakes affect the integrity of structures. Essentially those already built and especially vulnerable to this type of action, as is the case of many existing buildings on significant seismic activity zones which are not adequately prepared for that eventuality. Consequently, there is also the need to perform a significant number of studies of repairing procedures of structural elements, so as to restore its function and possibly achieve an improvement in relation to its original seismic resistance. The present experimental work is focused in the study of welding joints for steel bars used in building columns, supported by tensile tests on specimens according to the actual welding regulations. The experimental results are analyzed and discussed with particular attention to the specimens' behaviour in terms of strength and ductility compared to the results obtained for original steel bars. After the definition of the proper welding solution, six RC columns previously tested were repaired and retrofitted with this solution tested under uniaxial and biaxial horizontal loading and variable axial load in order to compare the global result with the original tested columns and the effects introduced by the repair process. Adequate detailing can improve the structure seismic behaviour by (H. Rodrigues).Engineering Structures 155 (2018) 371-386 0141-0296/

Strengthening and Repair of Reinforced Concrete Columns by Jacketing: State-of-the-Art Review

“…More recently, Rodrigues et al [13] repaired severely damaged RC columns by replacing the damaged concrete in the plastic hinge region with high-strength micro-concrete and welding of ruptured longitudinal bars. The subsequent testing of the repaired columns under bi-directional lateral loading with constant axial compression showed that the repair technique fully restored the strength and ductility of the columns; however, the stiffness was still lower than in the original specimen.…”

Influence of seismic loading on axial load variation in reinforced concrete columns

“…By analyzing the experimental results, they found that the variation in the axial load, along with horizontal loads, led to an increase in stiffness and maximum strength, and that the strength degradation was higher for high axial load values and decreased when the values of axial forces decreased [17,18]. More recently, Rodrigues et al [11,19] performed a test campaign to investigate one of the gaps identified in the previous studies and proceeded to evaluate the behavior of six RC columns subjected to biaxial horizontal loading under variable axial load. Thus, the effect of axial load variation was evaluated throughout the experimental tests, in terms of damage evolution, global inelastic behavior, stiffness degradation, strength degradation, and energy dissipation.…”

Seismic Damage Model of Bridge Piers Subjected to Biaxial Loading Considering the Impact of Energy Dissipation

“…This fact indicates that the seismic performance of a structure, including the ultimate load-bearing capacity, the stiffness degeneration, and the strength degradation could be influenced by more than one directional seismic excitation. Several studies have shown that the failure characteristics of structures under multi-direction loadings are more complicated due to the multi-axial coupling effect [13][14][15][16][17][18]. The crack resistance, energy absorption capacity, damage propagation, and ductility of the RC bridge columns under biaxial horizontal cyclic loading usually differs markedly from that under uniaxial loading [14][15][16][17]19].…”