“…It is reasonably highlighted in past studies that floor amplification is strongly dependent on the dynamic characteristics of the supporting structure and torsional response of the supporting structure leads to increased floor acceleration demands at the FE . Hill‐side buildings have signifcantly different structural configuration as compared with regular buildings located on plane topography, resulting in significantly different dynamic chracteristics while also exhibiting torsional effects in the across‐slope direction .…”
Section: Background Studiesmentioning
confidence: 96%
“…A comprehensive state‐of‐the‐art review on the seismic design of NSCs in context of regular buildings has already been reported in earlier studies . Past studies on the evaluation of floor acceleration demands can be broadly classified under the categories of studies based on both single‐degree‐of‐freedom and multiple‐degree‐of‐freedom modeling of the supporting structure. The parameters affecting the floor response, identified in these studies, include the dynamic characteristics (periods and mode shapes) of the supporting structure, the input seismic ground motion characteristics, and the inelasticity (ductility demand) of the supporting structure .…”
Section: Background Studiesmentioning
confidence: 99%
“…Contrary to regular buildings, very few studies have focused on the floor response of irregular buildings . Mohammed et al carried out experimental investigations on NSCs mounted on stiffness‐ and mass‐eccentric torsionally yielding supporting structures, through shake‐table tests.…”
Section: Background Studiesmentioning
confidence: 99%
“…They further concluded that Eurocode 8 predictions underestimated acceleration demand for NSCs attached to the flexible side, under tuned conditions, by 36% and 28.2%, for site class A and E, respectively. Later on, it was attributed to the fact that the Eurocode 8 model does not take into account the floor amplification caused by torsional response of the supporting structure . In addition, the torsional amplification factors (TAFs; defined as the ratio of peak component accelerations at the FE to CR) were found to be well correlated with the floor rotation as well as angular accelerations …”
Section: Background Studiesmentioning
confidence: 99%
“…37,55,61 Contrary to regular buildings, very few studies have focused on the floor response of irregular buildings. [57][58][59][60] Mohammed et al 57 carried out experimental investigations on NSCs mounted on stiffness-and mass-eccentric torsionally yielding supporting structures, through shake-table tests. It was reported that the torsional yielding of the supporting structure has significant implications on the deamplification of near-tuned secondary system response.…”
Summary
A suite of reinforced‐concrete frame buildings located on hill sides, with 2 different structural configurations, viz step‐back and split‐foundation, are analyzed to study their floor response. Both step‐back and split‐foundation structural configurations lead to torsional effects in the direction across the slope due to the presence of shorter columns on the uphill side. Peak floor acceleration and floor response spectra are obtained at each storey's center of rigidity and at both its stiff and flexible edges. As reported in previous studies as well, it is observed that the floor response spectra are better correlated with the ground response spectrum. Therefore, the floor spectral amplification functions are obtained as the ratio of spectral ordinates at different floor levels to the one at the ground level. Peaks are observed in the spectral amplification functions corresponding to the first 2 modes in the upper portion of the hill‐side buildings, whereas a single peak corresponding to a specific kth mode of vibration is observed on the floors below the uppermost foundation level. Based on the numerical study for the step‐back and split‐foundation hill‐side buildings, simple floor spectral amplification functions are proposed and validated. The proposed spectral amplification functions take into account both the buildings' plan and elevation irregularities and can be used for seismic design of acceleration‐sensitive nonstructural components, given that the supporting structure's dynamic characteristics, torsional rotation, ground‐motion response spectrum, and location of the nonstructural components within the supporting structure are known, because current code models are actually not applicable to hill‐side buildings.
“…It is reasonably highlighted in past studies that floor amplification is strongly dependent on the dynamic characteristics of the supporting structure and torsional response of the supporting structure leads to increased floor acceleration demands at the FE . Hill‐side buildings have signifcantly different structural configuration as compared with regular buildings located on plane topography, resulting in significantly different dynamic chracteristics while also exhibiting torsional effects in the across‐slope direction .…”
Section: Background Studiesmentioning
confidence: 96%
“…A comprehensive state‐of‐the‐art review on the seismic design of NSCs in context of regular buildings has already been reported in earlier studies . Past studies on the evaluation of floor acceleration demands can be broadly classified under the categories of studies based on both single‐degree‐of‐freedom and multiple‐degree‐of‐freedom modeling of the supporting structure. The parameters affecting the floor response, identified in these studies, include the dynamic characteristics (periods and mode shapes) of the supporting structure, the input seismic ground motion characteristics, and the inelasticity (ductility demand) of the supporting structure .…”
Section: Background Studiesmentioning
confidence: 99%
“…Contrary to regular buildings, very few studies have focused on the floor response of irregular buildings . Mohammed et al carried out experimental investigations on NSCs mounted on stiffness‐ and mass‐eccentric torsionally yielding supporting structures, through shake‐table tests.…”
Section: Background Studiesmentioning
confidence: 99%
“…They further concluded that Eurocode 8 predictions underestimated acceleration demand for NSCs attached to the flexible side, under tuned conditions, by 36% and 28.2%, for site class A and E, respectively. Later on, it was attributed to the fact that the Eurocode 8 model does not take into account the floor amplification caused by torsional response of the supporting structure . In addition, the torsional amplification factors (TAFs; defined as the ratio of peak component accelerations at the FE to CR) were found to be well correlated with the floor rotation as well as angular accelerations …”
Section: Background Studiesmentioning
confidence: 99%
“…37,55,61 Contrary to regular buildings, very few studies have focused on the floor response of irregular buildings. [57][58][59][60] Mohammed et al 57 carried out experimental investigations on NSCs mounted on stiffness-and mass-eccentric torsionally yielding supporting structures, through shake-table tests. It was reported that the torsional yielding of the supporting structure has significant implications on the deamplification of near-tuned secondary system response.…”
Summary
A suite of reinforced‐concrete frame buildings located on hill sides, with 2 different structural configurations, viz step‐back and split‐foundation, are analyzed to study their floor response. Both step‐back and split‐foundation structural configurations lead to torsional effects in the direction across the slope due to the presence of shorter columns on the uphill side. Peak floor acceleration and floor response spectra are obtained at each storey's center of rigidity and at both its stiff and flexible edges. As reported in previous studies as well, it is observed that the floor response spectra are better correlated with the ground response spectrum. Therefore, the floor spectral amplification functions are obtained as the ratio of spectral ordinates at different floor levels to the one at the ground level. Peaks are observed in the spectral amplification functions corresponding to the first 2 modes in the upper portion of the hill‐side buildings, whereas a single peak corresponding to a specific kth mode of vibration is observed on the floors below the uppermost foundation level. Based on the numerical study for the step‐back and split‐foundation hill‐side buildings, simple floor spectral amplification functions are proposed and validated. The proposed spectral amplification functions take into account both the buildings' plan and elevation irregularities and can be used for seismic design of acceleration‐sensitive nonstructural components, given that the supporting structure's dynamic characteristics, torsional rotation, ground‐motion response spectrum, and location of the nonstructural components within the supporting structure are known, because current code models are actually not applicable to hill‐side buildings.
This paper presents a study of acceleration demands in low-rise reinforced concrete (RC) buildings with torsion, evaluated by quantifying peak floor accelerations (PFAs) and floor response (acceleration) spectra (FRS). The study was performed with the aim to provide simple empirical formulas to quantify the amplification effects due to torsion, which can occur in most of the existing and new RC buildings. With this goal in mind, a set of eight archetype buildings was selected, characterized by an increasing floor eccentricity obtained by moving the centre of rigidity (CR) away from the centre of mass (CM). Numerical models of the proposed set of archetype RC buildings were considered in both linear elastic and nonlinear configurations. For the latter, the properties of models were widely varied, by systematically modifying parameters of plastic hinges, in order to obtain a sample of 1000 models. Non-structural components (NSCs) were considered linear elastic in all cases. To investigate acceleration demands, a set of forty Eurocode 8 spectrum-compatible ground motion records were used as input. For linear elastic building models, it was observed that the change of demands depends on the position of the NSC (in-plan and in-height), and on the distance between CR and CM. On the other hand, for nonlinear models, additional parameters must be considered, such as the building ductility (μ) and yielding force (Vy). New regression models were proposed for quantifying the observed differences in PFAs and FRS when torsion occurs. The efficiency of the proposed models was assessed by testing the new formulas on an existing case study building, as well as on the well-known SPEAR building.
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