Dynamic Behavior of Rocking and Hybrid Cantilever walls in Precast Concrete Building

Abstract

His research activities include the seismic design and retrofit of precast and reinforced concrete bridges and buildings.

Finite Element Modeling of “Rocking Walls”

“…From the graph it is possible to see how the 2D elements model is able to describe the global rocking wall behavior and to capture base shear peaks for wall base rotations close to zero. These peaks are associated to horizontal acceleration spikes (Figure 11) arising when the wall gains horizontal lateral stiffness in the unloading phase, as explained and showed elsewhere [12,23], which happens in proximity of zero base rotation. Figure 11 shows horizontal (a h ) and vertical (a v , positive upward, acceleration of gravity excluded) acceleration time histories at the wall 3 rd floor.…”

“…Figure 11 shows horizontal (a h ) and vertical (a v , positive upward, acceleration of gravity excluded) acceleration time histories at the wall 3 rd floor. The peaks in vertical acceleration arise when the wall base gap closes [12] and show higher values compared to experimental test due to the increased stiffness of the foundation beam model compared to the actual tested structure. Regarding 1D elements models, the comparison is made between two damping formulations, Rayleigh (R) damping and stiffness proportional (SP) damping, both considering tangent stiffness proportionality at each time increment in the damping matrix definition.…”

“…Detailed information on the test specimen geometry, material tests and loading sequence can be found elsewhere [11,12].…”

“…The dynamic interaction between rocking and hybrid walls and the rest of the structure was investigated during the DSDM project [10] in which shake table tests were conducted on a three story half-scale precast concrete structure whose lateral force resisting system consisted entirely on rocking and hybrid walls [11,12].…”

“…The present paper focuses on numerical modeling of rocking walls investigating the effects of different modeling techniques in both nonlinear static and dynamic analyses. The rocking wall chosen as reference for the present study is extrapolated from the aforementioned DSDM project [11,12]. Being the aim of the paper the investigation of finite modeling techniques, there is no interest in modeling the whole building in order to capture rocking wall and floors interaction and wall foundation influence; therefore the floors are modeled as point masses and the foundation is deliberately made rigid.…”