Stiffness-Displacement Correlation from the RC Shear Wall Tests of the SAFE Program: Derivation of a Capacity Line Model

Abstract

The response of 13 reinforced concrete shear walls submitted to successive seismic tests has been postprocessed to produce time histories of secant stiffness and displacement oscillation amplitude. For every wall an envelope curve of displacement amplitude versus stiffness is identified which is fairly modelled by a straight line in double logarithmic scale. This relatively simple model, when used as a capacity line in combination with the demand response spectrum, is able to predict in an approximate manner the maximum response to the applied earthquakes. Moreover, the graphic representation of the demand spectrum and a unique model capacity line for a group of equal walls with different assumed design frequencies on them gives a visual interpretation of the different safety margins observed in the experiments for the respective walls. The same method allows as well constructing vulnerability curves for any design frequency or spectrum. Finally, the comparison of the different identified line models for the different walls allows us to assess the qualitative effect on the behaviour of parameters such as the reinforcement density or the added normal load.

Assessment of a capacity spectrum seismic design approach against cyclic and seismic experiments on full‐scale precast RC structures

“…The experimental curves available are the ones associated to the PsD tests only. These results were analyzed to get a series of EVD curves (see Molina et al for details on the procedure used), as shown in the succeeding part of the paper. If adopting the experimental EVD curve, which is characterized by a larger EVD in the displacement region of interest, the performance point is found at a sensibly low value along the capacity curve, which is also in accordance with the experimental observation.…”

“…The method proposed by Molina et al to determine the EVD factors directly from the results of PsD tests brings to the curves reported in Figure 11 in comparison with those obtained from cyclic tests. Moreover, Molina et al use a capacity line obtained from the PsD results as well, which should match the RS spectrum in the ADRS representation. Such capacity line is derived from the simultaneous identification of linear stiffness and damping properties and is necessary to avoid the need of cyclic tests or any numerical simulations.…”

“…Sources of error within the present application of the method come from the existing difference between the EVD curves evaluated from cyclic tests-or numerical in case C-and the effective damping occurred during the PsD tests. The method proposed by Molina et al 62 to determine the EVD factors directly from the results of PsD tests brings to the curves reported in Figure 11 in comparison with those obtained from cyclic tests. Moreover, Molina et al 62 use a capacity line obtained from the PsD results as well, which should match the RS spectrum in the ADRS representation.…”

“…Its definition has been usually provided for symmetric hardening structural systems, while in Priestley et al, a more general definition is provided. However, some authors suggest referring to an explicit viscous‐type related specific energy. An alternative version for wall structures based on a reduced elastic deformation energy, whose accuracy is not studied in the present paper, was proposed in Igarashi…”

Investigation on the Structural Behavior of Shear Walls with Steel Truss Coupling Beams under Seismic Loading

“…Nonlinear seismic response of walls coupled with steel and concrete beams was also investigated [4][5][6]; the research demonstrated the advantages of using steel beams to couple reinforced concrete walls. Experiments and simulations have been conducted on the joints of steel CBs and shear walls [7][8][9][10][11], and the results demonstrated that the anchorage has important impacts on the stiffness degradation; the shear yield style steel CB has excellent ductility performance and energy performance, construction convenient, and easy maintenance and replacement, and especially the maintenance can be easily replaced after the earthquake. Wu [12] investigated the steel CB and concrete shear wall joints by employing experiments and finite element analysis, the failure mode of joints, strain distribution, bearing capacity, CB size, concrete strength, ductility, and hysteretic behaviors were studied.…”