• Earthquakes and Structures
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• v.10 no.6
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• pp.1405-1428
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• 2016

Besides the complex instructions of guidance documents for seismic rehabilitation of existing buildings, some institutions have provided simple criteria in terms of simplified rehabilitations. ASCE 41-06 is one of documents that introduced a simple method for assessment of certain buildings that do not require advanced analytical procedures. Furthermore the New Zealand guideline has presented a simple lateral mechanism analysis that is a hand static analysis for determining the probable collapse mechanism, lateral strength and displacement capacity of the structure. The present study is focused on verifying the results of the simplified methods which is used by NZSEE and ASCE 41-06 in assessment of existing buildings. For this, three different special steel moment and braced frames are assessed under these two guidelines and the accuracy of the results is checked with the results of nonlinear static and dynamic analysis. After comparison of obtained results, suggestions are presented to improve seismic retrofit criteria.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.1
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• pp.33-43
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• 2018

'Seismic Performance Evaluation Method for Existing Buildings (2013)' developed in accordance with the overseas guidelines ASCE 41 - 06 is the most widely used procedure among domestic seismic performance evaluation guidelines in Korea. However, unlike ASCE 41 - 06, it stipulates that the final performance should be derived as the gravity load distribution ratio of the lateral force resistance system in the guideline. Therefore, in the case of a dual steel structure system with slender braces, where the internal moment frame is mostly responsible for the gravity load, the evaluation of slender braces based on gravity load distribution ratio is difficult to be achieved. In this research, we propose an objective evaluation process for such system by evaluating seismic performance for large-scale factory facilities as an example.

• Earthquakes and Structures
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• v.10 no.3
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• pp.539-562
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• 2016

The seismic behavior of a ${\frac{1}{2}}$ scaled, three-story three-bay RC frame with masonry infill walls was studied experimentally and numerically. Pseudo-dynamic test results showed that despite following the column design provisions of modern seismic codes and neglecting the presence of infill walls, shear induced damage is unavoidable in the boundary columns. A finite element model was validated by using the results of available one-story one-bay frame tests in the literature. Simulations of the examined test frame demonstrated that boundary columns are subjected to shear demands in excess of their shear capacity. Seismic assessment of the test frame was conducted by using ASCE/SEI 41-06 (2006) guidelines and the obtained results were compared with the damage observed during experiment. ASCE/SEI 41-06 method for the assessment of boundary columns was found unsatisfactory in estimating the observed damage. Damage estimations were improved when the strain limits were used within the plastic hinge zone instead of column full height.

• Earthquakes and Structures
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• v.10 no.4
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• pp.811-828
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• 2016

This study aims to present nonlinear time history analysis results of double leaf cavity wall (DLCW) reinforced concrete structure exposed to shake table tests. Simulation of the model was done by a Finite Element (FE) program. Shake table experiment was performed at the National Civil Engineering Laboratory in Lisbon, Portugal. The results of the experiment were compared with numeric DLCW model and numeric model of reinforced concrete structure with unreinforced masonry wall (URM). Both DLCW and URM models have two bays and two stories. Dimensions of the tested structure and finite element models are 1:1.5 scaled according to Cauchy Froude similitude law. The URM model has no experimental results but the purpose is to compare their performance level with the DLCW model. Results of the analysis were compared with experimental response and were evaluated according to ASCE/SEI 41-06 code.

• Earthquakes and Structures
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• v.13 no.3
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• pp.309-322
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• 2017

In this paper, a simplified evaluation method of the skeleton curve for reinforced concrete (RC) frame with unreinforced masonry (URM) infill is proposed in a practical form, based on the previous studies. The backbone curve for RC boundary frame was modeled by a tri-linear envelope with cracking and yielding points. On the other hand, that of URM infill was modeled by representative characteristic points of cracking, maximum, and residual strength; also, the interaction effect between RC boundary frame and the infill was taken into account. The overall force-displacement envelopes by the sum of RC boundary frame and URM infill, where the backbone curves of the infill from other studies were also considered, were then compared with the previous experimental results. The simplified estimation results from this study were found to almost approximate the overall experimental results with conservative evaluations, and they showed much better agreement than the cases employing the infill envelopes from other studies.

• Steel and Composite Structures
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• v.25 no.2
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• pp.217-229
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• 2017

The effect of column loss location on the structural response of steel moment resisting frames (MRF) is investigated in this study. A series of nonlinear static and dynamic analyses were performed to determine the resistance of a generic frame to an arbitrary column loss and detect the structural members that are susceptible to failure progression beyond that point. Both force-controlled and deformation-controlled actions based on UFC 4-023-03 and ASCE/SEI 41-06 were implemented to define the acceptance criteria for nine APM cases defined in this study. Results revealed that the structural resistance against an arbitrary column loss in the top story is at least 80% smaller than that of the bottom story. In addition, it was found that the dynamic increase factor (DIF) at the failure point is at most 1.13.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.5
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• pp.1-11
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• 2012

In this paper, non-linear analysis was performed for Reinforced Concrete (RC) walls using different macroscopic models subjected to cyclic loading, and the analytical results were compared with previous experimental studies of RC walls. ASCE41-06 (American Society of Civil Engineers) specifies that the hysteresis behaviors of RC walls are different due to the aspect ratio of the walls. For a comparison between analytical and experimental results, a slender wall with an aspect ratio exceeding 3.0 and a squat wall with an aspect ratio of 1.0 were selected among previous research works. For the non-linear analysis, each test specimen was modeled using two different macroscopic methods: the first representing the flexural behavior of the RC wall, and the second considering the diagonal shear in the web of the wall. Through nonlinear analysis of the considered RC walls, the analytical difference of a slender wall was negligible due to the different macroscopic modeling methods. However, the squat wall was significantly affected by the considered components of the modeling method. For an accurate performance evaluation of the RC building with squat walls, it would be reasonable to use a macroscopic model considering diagonal shear.

• Structural Engineering and Mechanics
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• v.55 no.5
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• pp.1037-1053
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• 2015

This paper presents finite element (FE) based pushover analysis of a reinforced concrete structure with a two-leaf cavity wall (TLCW) to estimate the performance level of this structure. In addition to this, an unreinforced masonry (URM) model was selected for comparison. Simulations and analyses of these structures were performed using the DIANA FE program. The mentioned structures were selected as two storeys and two bays. The dimensions of the structures were scaled 1:1.5 according to the Cauchy Froude similitude law. A shake table experiment was implemented on the reinforced concrete structure with the two-leaf cavity wall (TLCW) at the National Civil Engineering Laboratory (LNEC) in Lisbon, Portugal. The model that simulates URM was not experimentally studied. This structure was modelled in the same manner as the TLCW. The purpose of this virtual model is to compare the respective performances. Two nonlinear analyses were performed and compared with the experimental test results. These analyses were carried out in two phases. The research addresses first the analysis of a structure with only reinforced concrete elements, and secondly the analysis of the same structure with reinforced concrete elements and infill walls. Both researches consider static loading and pushover analysis. The experimental pushover curve was plotted by the envelope of the experimental curve obtained on the basis of the shake table records. Crack patterns, failure modes and performance curves were plotted for both models. Finally, results were evaluated on the basis of the current regulation ASCE/SEI 41-06.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.85-93
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• 2016

In this study, finite element analyses of masonry infilled frames using a general purpose FE program, ABAQUS, were conducted. Analysis models consisted of the bare frame, infilled frames with masonry wall thickness of 0.5B and 1.0B, respectively. The masonry walls were constructed using the concrete bricks which were generally used in Korea as infilled wall. The material properties of frames and masonry for the analysis were obtained from material tests. However, four times increased the tensile strength was used for 1.0B wall, which is seemingly due to the differences in locating the bricks. The force-displacement relation and development of crack from the FE analysis were very similar to those from the experiments. From the FEA results, contact force between the frame and masonry, distribution of shear force and bending moments in frame members were analyzed. Obtained contact stress shows a trianglur distribution, and the contact length for 0.5B speciment and 1.0B specimen were close to the value estimated using ASCE 41-06 equation and ASCE 41-13 equation, respectively. Obtained shear force and bending moment distribution seems to replicate actual behavior which originates from the contact stress and gap between the frame and masonry.