Dynamic Response of Lightweight Cellular Concrete MSE Walls

Abstract

Due to the numerous benefits that lightweight cellular concrete offers, its use has become increasingly popular in several construction applications. One specific application is as the backfill of retaining walls or MSE walls in order to reduce earth pressure, construction cost and time. Previous studies examined the static and dynamic properties of lightweight cellular concrete with varying test and dry unit weights through laboratory testing. Furthermore, numerical modelling evaluated the deformation characteristics of geo-grid reinforced lightweight cellular concrete backfills. However, results from physical model tests to validate these results are unavailable in the literature. Given the increasing use of these geo-grid reinforced lightweight cellular concrete backfills in seismically active regions, it is critical to observe the seismic performance of these structures. As such, shake table tests were performed on a 1.2 m tall lightweight cellular concrete (material with a test unit weight of 4 kN/m³) MSE wall reinforced with a geo-grid layer at approximately 0.6 m height. The models were instrumented with a series of accelerometers and strain gauges. Additionally, in order to simulate self-weight of the MSE walls of different heights, vertical stresses of approximately 5 kPa and 8 kPa were applied to the geo-gird reinforced lightweight cellular concrete before the structure was subjected to a series of sinusoidal ground motions with varying amplitudes and frequencies. Additionally, the geo-grid reinforced lightweight cellular concrete was also subjected to the ground motions recorded from the 1994 Northridge earthquake. The entire geo-gird reinforced lightweight cellular concrete backfill was found to displace as a single monolithic unit with no significant relative displacements between the geo-grid reinforcement layer and the lightweight cellular concrete. Furthermore, no fractures were observed during the application of the ground motions.