Energy dissipation models for RC members and structures

Abstract

Summary The unloading parameters of hysteretic models for RC members are given in terms of their shear‐span‐to‐depth ratio and the viscous damping used to model other energy dissipation sources. They reflect the energy dissipation in full post‐yield load cycles in 534 tests of rectangular or circular members. Pre‐yield hysteretic energy dissipation—ignored if the model is elastic till yielding—amounts in the tests to a mean viscous damping around 8.5% and can be considered in nonlinear response‐history analysis through a new model which combines constant elastic stiffness in virgin loading with hysteretic energy dissipation both before and after yielding. Models with linear behavior till yielding and hysteretic energy dissipation only after it come closer to the results of the new model if viscous damping is 5%.

Cracking behavior and energy consumption of Steel Fiber Concrete Encased Steel beams

“…The energy consumption of specimens S-R-1-360 and S-R-2-360 (E 3 ) were 10814.73 kNmm and 11515.79 kNmm, respectively, which represents a significant increase in energy consumption compared with beams without stirrups. However, the total energy consumption did not increase with decreasing stirrup spacing, contrarily to RC (Grammatikou et al, 2019) and SRC beams (Qin et al, 2012). Moreover, the simultaneous use of steel fibers, longitudinal reinforcements, and stirrups exhibited a complex coupling effect on the energy consumption capacity of the specimens.…”

Energy dissipation in reinforced concrete members before or after yielding

“…Several past works-e.g., [1][2][3][4][5][6] -have proposed empirical expressions giving the equivalent viscous damping ratio, ζ, in terms of the peak displacement ductility factor, μ, in a cycle of loading. Some of them fitted empirical μ-ζ formulae to a narrow strip of own test results.…”

“…In, ref. 6 instead, physical models, derived from two well-known hysteretic force-deformation laws, were chosen to describe the mathematical relation between μ and ζ. In addition, the parameters of these μ-ζ models were expressed in terms of the shear-span-(to-depth)-ratio and the dimensionless axial load of the member.…”

“…Moreover, unlike the models proposed in ref. 6 for the post-elastic range, which relate to two specific hysteretic force-deformation laws from literature [7][8][9] and do not generalize to other hysteresis laws, the models proposed here can be applied together with any type of post-yield hysteresis law. In addition, separate models developed for energy dissipation in the pre-yield range are seamlessly integrated with the post-yield model.…”

“…Last, but not least, the present work uses a database which is almost 2.5-times that in ref. 6 regarding the number of test specimens or load cycles. The added tests concern primarily members whose cyclic inelastic behavior is controlled by shear, or members with deficient detailing, not conforming to current-generation seismic design codes and standards: plain (smooth) longitudinal bars and lap-splicing of longitudinal bars, ribbed or plain, within the region where a plastic hinge develops.…”