Effect of reinforcement detailing in the seismic behavior of slender walls

Abstract

Significant damage was observed in reinforced concrete walls of residential buildings following the2010 Maule earthquake in Chile. The damage in structural walls was brittle and concentrated near theground level. The most common observed damage in such walls was crushing of concrete underflexural-compressive action, buckling and fracture of the vertical reinforcement, and opening ofhorizontal reinforcement. This damage is attributed to high axial loads, the limited wall thickness, theinadequate reinforcement detailing, and structural irregularities. The objective of this paper is tosummarize the experimental campaign of four 1/2-scale reinforced concrete walls (W1, W7, W8 andW9). The tests are aimed to assess the influence of the horizontal reinforcement detailing in theseismic behaviour of slender walls. Wall specimen W1 is referred to as the reference wall and wasdesigned following typical construction practice in Chile, with the horizontal bars bent with 90-degreee hook. Specimen W7 was designed with horizontal bars bent with 135-degree hooks, specimenW8 with additional closed stirrups in the wall boundaries, and specimen W9 with additional transversecross-ties. The aspect ratio of the walls was M/Vlw=2.5, and the thickness of the scaled specimens was100 mm. The walls were subjected to a constant axial load of c g f A ‘ 0.15 and were subjected to lateralcyclic displacements. It is concluded that the 135-degree hooks does not improve significantly thebehavior of slender walls. The use of closed stirrups at the wall boundaries are highly recommendedto reduce the likelihood of bar buckling, as well as to prevent out-of-plane buckling of the wall afterfailure.