Abstract
A one-fifth scale, two-story, two-bay reinforced lightweight aggregate concrete (LWAC) frame subjected to quasi-static cyclical loading was analyzed to investigate the seismic behavior of this innovative system, primarily focusing on the failure modes, plastic hinge mechanism, load-deformation response, skeleton curves, stiffness degradation and energy dissipation capability. Overall, the test demonstrates that the LWAC frame meets the requirement of a “strong-column and weak-beam, strong-joint and weak-member” design criteria, exhibiting a mixed failure mechanisms consisting of both the beam hinge mechanism and column hinge mechanism. The former was the predominant failure mechanism and was fully developed after reaching the peak load point, while the latter was the inevitable result in the final failure of the LWAC frame. The fatter hysteretic loop and the displacement ductility factor Δu/Δy of 3.49 observed from LWAC frame indicate excellent energy dissipation and reliable displacement ductility capability, which are comparable to those of NWC frames. The test data observed in this study can provide theoretical guidance for the application of LWAC frames in seismic regions.
Highlights
Lightweight aggregate concrete (LWAC) has many advantages including better durability, higher fire-resistance capacity, lower permeability and can effectively reduce the dead load and dimensions of elements while improving the seismic resistance capacity of building structures [1, 2]
The results of experiments and the analysis reported in this paper will help to characterize the seismic behavior of LWAC frames
This paper focused on determining the seismic behavior of LWAC frames by subjecting a onefifth scale two-story, two-bay test specimen to quasi-static cyclical loading that gave an indication of its ductility in a seismic event
Summary
Lightweight aggregate concrete (LWAC) has many advantages including better durability, higher fire-resistance capacity, lower permeability and can effectively reduce the dead load and dimensions of elements while improving the seismic resistance capacity of building structures [1, 2]. Many buildings constructed of LWAC, including the Olive View Hospital, were severely damaged or collapsed due to shear failure. Initial investigation showed that the brittle defects of LWAC might have been the main cause for the collapses, while subsequent studies indicated that the building collapses were mainly caused by the unreasonable consideration of ductility design and the insufficient configuration of lateral shear reinforcements. During the 1989 Loma Prieta earthquake with a magnitude of 6.9, high-strength LWAC columns in highway overpasses experienced serious damage due to the same causes, namely, insufficient shear reinforcements and poor ductility. It simultaneously emphasized that the compressive strength of LWAC should be lower than 34.5 MPa unless it can be ensured with proper ductility through experimental investigation
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