• International Journal of Concrete Structures and Materials
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• 제9권1호
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• pp.89-118
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• 2015

The geometric nonlinearity of off-diagonal bracing system (ODBS) could be a complementary system to covering and extending the nonlinearity of reinforced concrete material. Finite element modeling is performed for flexural frame, x-braced frame and the ODBS braced frame system at the initial phase. Then the different models are investigated along various analyses. According to the experimental results of flexural and x-braced frame, the verification is done. Analytical assessments are performed in according to three dimensional finite element modeling. Nonlinear static analysis is considered to obtain performance level and seismic behaviour, and then the response modification factors calculated from each model's pushover curve. In the next phase, the evaluation of cracks observed in the finite element models, especially for RC members of all three systems is performed. The finite element assessment is performed on engendered cracks in ODBS braced frame for various time steps. The nonlinear dynamic time history analysis accomplished in different stories models for three records of Elcentro, Naghan and Tabas earthquake accelerograms. Dynamic analysis is performed after scaling accelerogram on each type of flexural frame, x-braced frame and ODBS braced frame one by one. The base-point on RC frame is considered to investigate proportional displacement under each record. Hysteresis curves are assessed along continuing this study. The equivalent viscous damping for ODBS system is estimated in according to references. Results in each section show the ODBS system has an acceptable seismic behaviour and their conclusions have been converged when the ODBS system is utilized in reinforced concrete frame.

• Computers and Concrete
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• 제20권5호
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• pp.539-544
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• 2017

Shear walls have high stiffness and strength; however, they lack energy dissipation and repairability. In this study, an innovative slotted shear wall featuring vertical slots and steel energy dissipation connectors was developed. The ductility and energy dissipation of the shear wall were improved, while sufficient bearing capacity and structural stiffness were retained. Furthermore, the slotted shear wall does not support vertical forces, and thus it does not have to be arranged continuously along the height of the structure, leading to a much free arrangement of the shear wall. A frame-slotted shear wall structure that combines the conventional frame structure and the innovative shear wall was developed. To investigate the ductility and hysteretic behavior of the slotted shear wall, finite element models of two walls with different steel connectors were built, and pushover and quasi-static analyses were conducted. Numerical analysis results indicated that the deformability and energy dissipation were guaranteed only if the steel connectors yielded before plastic hinges in the wall limbs were formed. Finally, a modified D-value method was proposed to estimate the bearing capacity and stiffness of the slotted shear wall. In this method, the wall limbs are analogous to columns and the connectors are analogous to beams. Results obtained from the modified D-value method were compared with those obtained from the finite element analysis. It was found that the internal force and stiffness estimated with the modified D-value method agreed well with those obtained from the finite element analysis.

• 한국지진공학회논문집
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• 제14권5호
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• pp.33-39
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• 2010

본 연구는 Modal Pushover Analysis(MPA)를 기반으로 비탄성 변위비(inelastic displacement ratio, $C_R$)와 붕괴 강도비(collapse strength ratio, $R_C$)를 이용한 간략한 Incremental Dynamic Analysis (IDA) 해석법을 제안해 냈다. 이 해석법은 선형 또는 비선형 동적해석 수행 없이 다자유도 시스템의 응답을 계산하기 때문에 간단하게 IDA곡선을 얻을 수 있다. 제안한 방법의 정확성은 6층, 9층, 20층의 철골 모멘트 골조를 대상으로 44개의 지진데이터를 사용하였으며 본 연구에서 제안하는 MPA를 이용한 $C_R-R_C$ IDA 해석결과와 비선형 동적해석 (Nonlinear Response History Analysis)을 통한 IDA 응답값, 그리고 각 주요모드의 비선형 동적해석을 통한 MPA-IDA 응답 값을 비교하여 타당성을 확인하였다. MPA를 이용한 $C_R-R_C$ IDA 해석법은 반복된 비선형 동적해석 과정이 없기 때문에 계산시 소요시간이 가장 작았으며 비교적 정확한 결과를 나타냈다.

• Steel and Composite Structures
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• 제33권1호
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• pp.19-36
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• 2019

Cyclic behaviour of composite (steel-concrete) plate shear walls (CPSW) with variable column flexural stiffness is experimentally and numerically investigated. The investigation included design, fabrication and testing of three pairs of one-bay one-storey CPSW specimens. The reference specimen pair was designed in way that its column flexural stiffness corresponds to the value required by the design codes, while within the other two specimen pairs column flexural stiffness was reduced by 18% and 36%, respectively. Specimens were subjected to quasi-static cyclic tests. Obtained results indicate that column flexural stiffness reduction in CPSW does not have negative impact on the overall behaviour allowing for satisfactory performance for up to 4% storey drift ratio while also enabling inelastic buckling of the infill steel plate. Additionally, in comparison to similar steel plate shear wall (SPSW) specimens, column "pull-in" deformations are less pronounced within CPSW specimens. Therefore, the results indicate that prescribed minimal column flexural stiffness value used for CPSW might be conservative, and can additionally be reduced when compared to the prescribed value for SPSWs. Furthermore, finite element (FE) pushover simulations were conducted using shell and solid elements. Such FE models can adequately simulate cyclic behaviour of CPSW and as such could be further used for numerical parametric analyses. It is necessary to mention that the implemented pushover FE models were not able to adequately reproduce column "pull-in" deformation and that further development of FE simulations is required where cyclic loading of the shear walls needs to be simulated.

• Earthquakes and Structures
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• 제24권1호
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• pp.37-51
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• 2023

Türkiye has made significant changes and updates in both seismic risk maps and design codes over time, as have other countries with high seismic risk. In this study, the last two seismic design codes and risk maps were compared for the Aegean Region (Western Türkiye) where the earthquake risk has once again emerged with the 2020 Izmir Earthquake (Mw=6.9). In this study, information about the seismicity of the Aegean Region was given. The seismic parameters for all provinces in the region were compared with the last two earthquake risk maps. The spectral acceleration coefficients of all provinces have increased and differentiated with the current seismic hazard map as a result of the design spectra used on a regional basis have been replaced by the geographical location-specific design spectra. In addition, section damage limits were obtained for all provinces within the scope of the last two seismic design codes. Structural analyses for a sample reinforced-concrete building were made separately for each province using pushover analysis. The deformations in the cross-sections were compared with the limit states corresponding to the damage levels specified in the last two seismic design codes for the region. Target displacement requests for all provinces have decreased with the current code. The differentiation of geographical location-specific design spectra both in the last two seismic design code and between provinces has caused changes in section damages and building performance levels. The main aim of this study is to obtain and compare both seismic and structural analysis results for all provinces in the Aegean Region (Western Türkiye).

• Coupled systems mechanics
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• 제7권3호
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• pp.281-295
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• 2018

This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.

• Steel and Composite Structures
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• 제8권1호
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• pp.35-52
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• 2008

The paper investigates the seismic performance of a Partially-Restrained (PR) steel-concrete composite frame using the probabilistic approach. The analysed frame was tested at the ELSA laboratory of the Joint Research Centre of Ispra (Italy), while the representative beam-to-column composite connections were tested at the Universities of Pisa, Milan and Trento (Italy). The component modelling of both interior and exterior composite joints is described first, including the experimental-numerical validation. The Latin Hypercube method has been used to draw the probabilistic distribution curves of joints, and then the whole PR composite frame has been analysed. Pushover and incremental dynamic analyses have been carried out using the non-linear FE code SAP2000 version 9.1. The fragility and performance curves of the PR composite frame have been determined for four damage limit states.

• Coupled systems mechanics
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• 제6권4호
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• pp.523-537
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• 2017

This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.305-312
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• 1999

A four-story reinforced concrete frame building model is designed for the gravity loads. only Static nonlinear pushover analyses are performed in two orthogonal horizontal directions. The overall capacity curves are converted into ADRS spectra and compared with demand spectra. At several points the deformed shape moment and shear distribution are calculated. It is observed that the seismic capacity may not meet the design requirements in soft soil condition and may collapse in MCE. It is concluded that limited but adequate amount of ductility need be provided in the seismic design in low to moderate seismicity regions.

• Steel and Composite Structures
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• 제50권6호
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• pp.643-658
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• 2024

The main aim of this study is to quantify the code seismic design coefficients of the RCS system, which consisted of reinforced concrete columns and steel beams, based on the FEMA P-695 methodology. The underlying intention is to evaluate the seismic performance of the RCS system at the system level rather than the connection level. A set of 24 archetype buildings with a various number of stories, beam span lengths, gravity load levels, and seismic load levels are selected and designed based on the prevailing code requirements. Nonlinear analytical models are developed and validated by experimental tests. The pushover and response history dynamic analyses are conducted to evaluate the required data in the performance quantification process. The results show that the design coefficients suggested by the code are acceptable. However, the level of conservatism is very high. Thus, it is possible to use a larger R-factor in the design process or make some relaxations in the design requirements related to this structural system.