Abstract
Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member’s loss factor and stress amplitude was derived based on Lazan’s damping-stress function. Then, the influence of stress amplitude on the loss tangent of RAC was experimentally investigated. Finally, parameters used to determine the newly derived function were obtained by numerical fitting. It is shown that the member’s loss factor is affected not only by the stress amplitude but also by factors such as the cross section shapes, boundary conditions, load types, and loading positions. The loss tangent of RAC increases with the stress amplitude, even at low stress amplitude. The damping energy exponent of RAC is not identically equal to 2.0, indicating that the damping is nonlinear. It is also found that the energy dissipation capacity of RAC is superior to that of natural aggregate concrete (NAC), and the energy dissipation capacity can be further improved by adding modified admixtures.
Highlights
Damping reflects energy dissipation, and it is one of the intrinsic dynamic characteristics of a material
Compared with the loss tangents at the exciting force amplitude of 50 N, the loss tangents at the exciting force amplitude of 200 N increased by 5.8% (RCA-0), 3.9% (RCA-30), 6.0% (RCA-70), 20.1% (RCA-micro-silica fume (MSF) + polypropylene fiber (PF)), 16.0% (RCA-rubber powder (RP) + steel fiber (SF)), and 13.6% (RCA-FA + ultrafine slag (US)), respectively
Compared with the loss tangent of recycled coarse aggregate (RCA)-0 at the exciting force amplitude of 200 N, the loss tangents increased by 1.2% (RCA-30), 5.5% (RCA-70), 20.1%
Summary
It is one of the intrinsic dynamic characteristics of a material. It strongly affects a structure’s dynamic response and damage evolution. Many studies have focused on the influence of admixtures on the damping of concrete; few studies have investigated the influence of coarse aggregate, especially recycled coarse aggregate (RCA). Chung et al [1,2,3,4] studied the damping capacity and storage modulus of cement paste and mortar with silica fume, latex, methycellulose, and graphite as admixtures. Neithalath et al [5] investigated the influence of morphologically altered cellulose fibers on the acoustic and damping characteristics of cement mortar
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