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This study aims to evaluate influences of isolation made using friction pendulum type isolators on seismic behavior of irregular mid-rise RC frame buildings without shear walls. For this at first, a 4-storey 3D reference building model which have no irregularity is designed as residential building. Afterwards, models including heavy overhang, short...
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... In addition, beams in x direction between columns to which overhangs are connected, have been removed due to presence of beams on ceiling unfavorable affecting appearance aesthetically and architectural needs in application. The plan view of heavy overhang (HO) buildings with protrusions on both sides created using regular building is given in Fig. ...
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Citations
... Increasing the structure's stiffness reduces the vibration period, causing a rise in acceleration and amplified seismic loads. Concurrently, higher ductility contributes to an increase in interstory drift demands [6,7]. The negative side of this method is that the building has to absorb all the lateral forces induced by the seismic ground motion. ...
This study evaluates seismic mitigation methods, including high damping rubber bearing, lead rubber bearing, double sliding pendulum (DSP), and tuned mass damper (TMD), considering earthquake intensity, building height, and isolation level. Moreover, the study delves into a novel approach that incorporates multi-level isolation and multi-level TMD. Reinforced concrete buildings, ranging in height from 4 to 40 storeys, were nalysed and nalysed using SAP2000 under the seismic influence of the Badra, El Centro, and Northridge earthquakes. The study reveals a significant rise in the fundamental period (T) with base isolation systems, reaching 378% of the fixed base value for a six-storey building. Building height directly affects T values, with simplified equations introduced for calculation. DSP proves 5% more efficient in reducing base shear (BS), while TMD is effective in weaker earthquakes for minimizing lateral displacement. Base isolators outperform mid-level isolation and TMD at the top storey. Combining base isolators with TMD at the top storey is deemed impractical and uneconomical. The study recommends multilevel isolation or multilevel TMD for enhanced seismic isolation efficiency, with four-level isolation achieving an 80% reduction in BS for 12-storey buildings. In addition, four-level TMD outperforms TMD at the top storey with a 44.5% reduction in BS, surpassing the 26.6% reduction achieved with TMD at the top storey only.
... Therefore, investigating the effects of irregularity on the performance of the structure is very practical and necessary [1][2][3]. The most important structural irregularities include the following: -Vertical stiffness: the lateral stiffness in every story is less than 70% of the adjacent story [4]. ...
... -Mass: The effective mass in the story is more than 150% of the effective mass in the upper or lower story [4]. -Vertical geometry: The horizontal dimension of the bearing system against the story lateral force is more than 130% of the adjacent story [5]. ...
... From the investigation, it is found that providing floating column in irregular buildings development drift and displacement in story. Meral [4] investigation of the friction pendulums effects on irregular buildings. So, a 4-story structure which has no irregularity is modeled. ...
Irregular structures have special seismic performance during earthquakes. Major irregularities in structural standards include geometric, torsional, diaphragm, out-of-plane and non-parallel. In the present paper, 5, 8 and 11-story steel structures with mass and height irregularities were modeled with SAP2000 software. The structures were subjected to 11 scaled earthquakes (near and far-fault) by nonlinear time history analysis method (direct integration). Steel structures have three types of concentrically braces including Gate, Inverted V and Knee. The results showed that the Knee brace has the best performance in the acceleration and displacement parameters of the structure. Inverted V brace has the best performance in shear force parameter. The average displacement reduction of irregular steel structures (5, 8 and 11-story) with Gate, Inverted V and Knee braces is 39.26%, 23.15%, and 49.65%, respectively. The average acceleration reduction of irregular steel structures (5, 8 and 11-story) with Gate, Inverted V and Knee braces is 28.56%, 17.23%, and 45.98%, respectively. The average reduction of column shear force in irregular steel structures (5, 8 and 11-story) with Gate, Inverted V and Knee braces is 14.11%, 24.48%, and 9.51%, respectively.
... Displacement demands with respect to the ground are at least two times higher for all base-isolated models. The difference of total displacement demand ratios is increased up to 8 times in FPS type isolators as observed in previous studies (Erduran 2011;Ismail 2015;Meral 2021). However, significant part of displacement demands is absorbed at the isolator interface. ...
This study aims to compare seismic response of fixed-base and most preferred base isolation models including lead rubber bearing (LRB), curved surface friction bearing (FPS) and flat slider (FS) types for regular low- and mid-rise reinforced concrete (RC) framed buildings. For this purpose, 352 nonlinear time history analyses of three-dimensional building models were carried out considering 11 different ground motion pairs. Most important parameters related to seismic behavior of base-isolated systems such as displacement and acceleration demands, interstory drift ratios, base shear demands and isolator capacity usage ratios were investigated. The fixed-base models were subjected to the highest seismic demands as expected. While significant part of individual analysis cases exceeded controlled damage state for fixed-base models, only a few cases reached limited damage state in base-isolated models. Although total lateral displacement values are much higher for base-isolated models, significant part of seismic demands is damped at isolator interface and transmitted demands are at negligible level. Obtained results indicated that using LRB and FS type isolators together causes increase in seismic demands compared to the use of only LRB isolators since FS type isolators cannot generate recall force. LRB type isolators seem to be a better choice for regular buildings that have not re-centering problem. Significant variation under different ground motion records is also observed for all analysis case. For that reason, it has great importance to use sufficient number of ground motion records for proper seismic performance evaluation.
... Habib et al. [33] researched the regular and irregular reinforced concrete structural models with seismic isolators exposed to pulse-like earthquakes with low and high PGA/PGV ratios. Meral [34] investigated the effects of friction pendulum isolators on the seismic behavior of reinforced concrete buildings. For this purpose, four-story building models with no irregularities and with heavy overhangs, short columns, and soft story irregularities were examined by the time history analysis. ...
In this study, the seismic behavior of isolated- and fixed-base regular and irregular reinforced concrete structures was investigated. For this purpose, a three-dimensional, eight-story reference building model without any irregularity was designed in accordance with the Turkish Building Earthquake Code (TBEC-2018). Later, the building models with irregularities were created using the reference building model. In the building models with seismic isolators and fixed supports, fiber hinges were used for columns and beams to model nonlinear behavior. Moreover, nonlinear behavior at the isolation level was taken into account in building models with seismic isolators. Eleven different earthquake records were scaled using the geometric scaling method. Bi-directional nonlinear response history analysis (NRHA) was performed simultaneously for both horizontal components of the earthquake records in all building models. In addition to boundary analyses (Lower Bound and Upper Bound), which do not take into account the strength loss defined by the codes, analyses considering the strength loss as a result of heating in the lead core due to cyclical motion (Temperature Including) were carried out for building models with seismic isolators. In the analyses, displacement, acceleration, story drift ratio, base shear ratio, and damage mechanisms in the columns and beams obtained from the fixed-base and isolated-base structures were compared. In addition, the results of the analysis, in which the loss of strength due to temperature increase due to cyclical motion in the lead core is taken into account, were compared with the results obtained from the boundary analysis. As a result of the study, it was deduced that significant improvements were observed in the structural behavior of all regular and irregular models with seismic isolators under earthquake effects.
... erefore, this technology has the advantages of damping, energy dissipation, and foundation isolation. e friction pendulum system (FPS) has been utilized in engineering since it was initially developed by Professor Zayas of the University of California, Berkeley, in 1985 [16][17][18][19]. ere is a joint in the sliding block of the FPS, which keeps the sliding block horizontal when it slides along the slideway. e slideway has the same radius of curvature as the slide surface and is coated with low friction materials, such as polytetrafluoroethylene (Teflon). ...
Given the issues existing in the isolation technology of high-rise structures, this study displays a thorough examination ponder of three control strategies incorporating numerical and experimental investigation on high-rise structures, which include friction pendulum system (FPS) base isolation, the FPS inter-storey isolation, and the FPS dual isolation. Depending on the third-generation benchmark structure, a scaled 9-storey finite element model is designed, and the matching model of FPS is outlined and fabricated, as required by the geometric similarity criteria. Four typical ground motions and four types of peak ground acceleration (PGA) are considered to investigate the dynamic response of three control strategies. The findings demonstrate that the FPS dual isolation technology can viably smother that acceleration of the top layer of the high-rise structure, and the vibration reduction effect of the substructure will be additionally self-evident. For high-rise structures, the FPS dual isolation technology has a significant vibration decrease impact, not just during minor earthquakes but also even during vast earthquakes. The vibration reduction mechanism of FPS dual isolation technology combines tuned mass damper (TMD) and base isolation technology. Those inertial force drives of the superstructure suppress response from claiming substructure, and same time, substructure is the form of base isolation, which extends that structural period segregates the seismic vitality. The structural deformation can be spread between the lower isolation storey and the upper isolation storey, which effectively limits the floor displacement of the structure. The FPS dual isolation does not mainly reduce that essential mode response of the system and suppresses the response of the high-order mode, which will be the primary reason behind the tremendous vibration decreased impact of the long-period structure. Eventually, it is demonstrated that the finite element model can simulate the dynamic response of the FPS dual isolation system with acceptable accuracy and is suitable for further parametric analysis and comparison by comparing the numerical analysis with the experimental findings.
A Triple Friction Pendulum (TFP) base-isolated building is designed to reduce displacement during an earthquake. However, the appropriate torsional response of multi-storey RCC buildings under stochastic ground motion is still unclear. This paper proposes a new mathematical model to study the torsional response of a TFP base-isolated RCC building subjected to stochastic ground motions. Stochastic ground motions are generated by the Monte Carlo simulation technique. The study examines the torsional response of the base-isolated building through base eccentricity (eb/d), super-structure eccentricity (es/d), uncoupled torsional to lateral frequency ratio of super-structure (Ωs), uncoupled torsional to the lateral frequency of isolator (Ωb) and base shear. The displacement attained as a result of eccentricity is compared with the design-bearing displacement recommended by the China Building Code (GB-2005). The study reveals that the torsion caused by eccentricities significantly influences the torsional behaviour of base-isolated buildings. The TFP base-isolated building with Ωs > 1 is torsionally more stable and potential displacement is not more complex by increasing the value of eb/d. In contrast, the building with Ωs < 1 is torsionally elastic and potential displacement becomes more complex by increasing the value of eb/d. The effect of superstructure eccentricity decreases almost linearly when isolation eccentricities take place. As the time of the superstructure increases, the torsional response of the building also increases. The study concludes that the GB-2005 Standard's design isolator displacement is traditional for the isolation eccentricities.
The base isolation technique is a well-known strategy used for the seismic protection of structures. It introduces a highly deformable device between the structure and the foundation to isolate the main structure from the ground motions. Despite the continuous enhancement of base isolation techniques, the limitations of this strategy are well known to researchers and engineers. Base isolation systems undergo large displacement under strong earthquake motions, which usually results in structural damage and users’ discomfort. In this study, a magnetorheological (MR) damper is used to improve the performance of a benchmark base-isolated building by placing the MR damper between the base of the structure and the foundation. The soil-structure interaction (SSI) effect is included in the study by considering three types of soil, denoted dense, medium, and soft. The soil is introduced through two degrees of freedom, namely, sway and rocking, based on the cone simplified linear model. The MR damper parameters are optimized using a particle swarm optimization (PSO) algorithm under a set of benchmark earthquake records. The optimal local parameters related to each benchmark earthquake and soil type are averaged to obtain general optimum parameters. The acquired general optimum parameters are then used to study the dynamical response of the benchmark base-isolated building controlled by the MR damper, considering an array of 100 natural earthquake ground motions. The obtained results show an enhancement of the dynamic response under all soils conditions compared to non-optimized and base isolation only scenarios. Several engineering demand parameters (EDP) and response indicators were investigated in this study, including top floor and base displacements, inter-storey drift, storey drift, top floor acceleration, and base shear. The results obtained show the effectiveness of the optimization in improving the response of base-isolated structures. It also demonstrates the dependence of damper parameters on soil typologies.
