No abstract

This study investigated the concrete-to-concrete friction behavior under dynamic cyclic loading at different loading rates, vertical loads, and surface roughness. The present work answers essential questions about the dynamic behavior of concrete-to-concrete friction since most of the available literature deals with static or quasi-static loading conditions. To this end, an experimental program was devised by casting 96 concrete blocks. A total of 48 dynamic push–pull tests were performed on each pair of blocks (mobile top block and fixed bottom block). Test variables included three types of surface roughness, four different loading rates, and two normal stresses. Performance measures included the static and dynamic friction forces coefficients of static and kinetic friction in addition to effective stiffness and effective damping. Moreover, the test results showed that the static and kinetic friction coefficients, effective stiffness, and effective damping decrease with increasing loading rates. Moreover, increasing the normal stress increases the friction force, thus increasing the effective stiffness and reducing the effective damping surface for all surface roughness types. The effects of test variables on the hysteresis behavior were also investigated.

No abstract

This paper demonstrates the evaluation of the energy dissipation capacity of a steel damper made from mild steel plates through performing a finite element analysis simulating cyclic loading. Results aimed to obtain the damper characteristics incorporated in retrofitting frames to increase their seismic resistance and energy dissipation. The analysis has well captured the damper energy dissipation capacity and the effective stiffness. Results showed that stresses were concentrated on the diaphragm plate since it is the weakest part of the damper and where the failure is expected to occur. Also, the diaphragm plate was the first segment of the damper to yield and enter the plastic ranges.