Proposal of Damage Index Ratio for Low- to Mid-Rise Reinforced Concrete Moment-Resisting Frame with Setback Subjected to Uniaxial Seismic Loading

Abstract

A vertical irregularity setback in reinforced concrete (RC) building affects its performance and response especially subjected to earthquake ground motions. It is necessary to understand how the seismic damage is established due to setbacks and avoid damage concentration on the irregularity section. The objective of this study is to propose a formula to estimate the damage distribution along the height of the setback building from a geometric measure of the degree of irregularity. First, previous experimental tests for two types of setback buildings, a towered and a stepped setback frames, were analyzed to verify the accuracy of the frame analysis. The results of the frame analysis considerably matched the experimental test results. Furthermore, to study the relationship between the degree of setback and the distribution of damage, a parametric study was conducted using 35 reinforced concrete setback frames, consisting of models with stepped setback type and towered setback type with different degrees of setback. The inelastic dynamic analyses of all the frames under three earthquake ground motions were conducted. The irregularity indices proposed in literature were adopted to express the degree of setback and the structural damage was expressed by the Park–Ang damage index. Using nonlinear regression analysis, formulas to estimate damage index ratio between two main structure parts (tower and base) from setback indices were proposed. Finally, the proposed formula was applied to the experimental test results to confirm its validity.

The Effect of Span-to-Height Aspect Ratio to The Damage Index Ratio of RC Buildings with Vertical Irregularity Setbacks

“…After calculating the damage index for every element with Park-Ang damage index Park et al1985) and story damage index proposed by , the damage index ratio between tower part and base part can be calculated by using Equation 2, which originally proposed by Maulana et al (Maulana et al 2021) as follow.…”

“…The geometry irregularities are accommodated in the calculation of geometrical indices proposed by , the damage index ratio between tower part and base part can be calculated by using Equation 2, which originally proposed by Maulana et al (Maulana et al 2021) as follow.…”

“…Both proposals could forecast the damage index decently, but it is only overall damage index and only suits for horizonal irregularity, and to calculate the equations, dynamic analyses were still needed to retrieve the seismic responses. To overcome those limitations, Maulana, et al (Maulana, Enkhtengis & Saito 2021) proposed simpler formulas by only considering the irregularity indices to retrieve the damage index ratio, a ratio between maximum damage index of the tower part to the maximum damage index of the base part, specifically for the reinforced concrete building with irregularity setback. The idea was tested on the experimental shaking table tests by other researchers.…”

“…In this study, the effect of span-to-height ratio to damage index ratio of the reinforced concrete buildings with setbacks were observed. Four sets of 2D RC frames having setback with stepped type are adopted by following the previous research (Maulana et al 2021). The seismic response of the building is evaluated with nonlinear dynamic analyses under three different seismic input motions.…”

Application of Genetic Algorithm to Optimize Location of BRB for Reinforced Concrete Frame with Curtailed Shear Wall

“…In this study, nonlinear structural seismic response analyses are employed using STERA_3D, a software developed by the co-author [26]. In the previous study by Maulana et al [27], STERA_3D was used to conduct seismic response analyses for RC setback buildings, and the results were considerably matched with experimental shaking table tests.…”