Seismic behavior of full-scale wall piers with high-strength steel reinforcement

The introduction of openings in structural walls could cause unfavourable seismic behaviour, leading to stringent reinforcement requirements for wall piers. High-strength steel with a reduced amount of reinforcement has the potential to relieve reinforcement congestion. However, the effect of the reduced areas of high-strength steel on the seismic performance of wall piers remains largely unknown, impeding its application in earthquake-prone areas. Through experimental investigation, this research aimed to reveal the benefits and limitations of using high-strength steel in wall piers. Four full-scale wall pier specimens with a height-to-length aspect ratio of 2.8 were subjected to lateral loading and a constant axial load. The parameters that varied in the specimens included concrete strength, steel reinforcement yield strength, and loading type. Test results showed that the 50% reduction in the amount of high-strength steel reinforcement had minor influence on the failure mode and lateral load-resisting capability. However, it had implications for the flexure-shear interaction and ultimate load-resisting mechanism of wall piers. All tested wall piers experienced spalling and crushing along the diagonal strut although their peak average stress was less than the shear stress limit associated with the crushing of concrete struts, as recommended in ACI 318–19. The effective stiffness estimates per the existing code provisions were found to be consistently higher than the one measured for the tested wall piers.