• Structural Engineering and Mechanics
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• v.46 no.2
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• pp.213-229
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• 2013

Although performance based assessment procedures are mainly developed for reinforced concrete and steel buildings, URM (Unreinforced Masonry) buildings occupy significant portion of buildings in earthquake prone areas of the world as well as in IRAN. Variability of material properties, non-engineered nature of the construction and difficulties in structural analysis of masonry walls make analysis of URM buildings challenging. Despite sophisticated finite element models satisfy the modeling requirements, extensive experimental data for definition of material behavior and high computational resources are needed. Recently, nonlinear equivalent frame models which are developed assigning lumped plastic hinges to isotropic and homogenous equivalent frame elements are used for nonlinear modeling of URM buildings. The equivalent frame models are not novel for the analysis of masonry structures, but the actual potentialities have not yet been completely studied, particularly for non-linear applications. In the present paper an effective tool for the non-linear static analysis of 2D masonry walls is presented. The work presented in this study is about performance assessment of unreinforced brick masonry buildings through nonlinear equivalent frame modeling technique. Reliability of the proposed models is tested with a reversed cyclic experiment conducted on a full scale, two-story URM building at the University of Pavia. The pushover curves were found to provide good agreement with the experimental backbone curves. Furthermore, the results of analysis show that EFM (Equivalent Frame Model) with Dolce RO (rigid offset zone) and shell element have good agreement with finite element software and experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.6
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• pp.293-303
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• 2013

This paper deals with steel braced frame as increasing the lateral strength and ductility in order to seismic retrofit of existing buildings and discusses the designing criteria and calculation method of retrofitted buildings. The addition of steel braced frame can be effective for increasing the lateral strength and ductility of existing buildings. However, There is a problem in utilizing this method. It is the approach to provide an adequate connection between the existing RC frame and the installed steel braced frame, because global strength by failure mode(three type) depends on detail of connection and strength of existing RC frame. So, the designer must be confirmed if it satisfies the required performance or not. Failure mode of type I is the most appropriate for increasing the lateral strength and ductility. Seismic performance evaluation and strength calculation of seismic retrofit are performed by guideline by KISTEC(Korea Infrastructure Safety & Technology)'s "seismic performance evaluation and rehabilitation of existing buildings" and Japan Building Disaster Prevention Association. Buildings are modeled and non-linear pushover analysis are performed using MIDAS program.

• Journal of the Korea Concrete Institute
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• v.11 no.5
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• pp.89-98
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• 1999

This paper evaluates nonlinear response characteristics of precast concrete frame buildings. where plastics hinging occurs in the precast connection. Designs were developed for buildings of 5, 10 and 15 stories in hight for moderate seismic risk regions of the U. S. The responses of the buildings were analyzed using DRAIN-2DX and following Nonlinear static analysis procedure of ATC 19. The main variables of the analyses were the strength and stiffness of the connection. Also, for the analysis, the bi-linear response model, developed and inserted into the DRAIN-2DX program by Shan Shi and D. Fouch, was used. With the results of analysis, the deformation demands of the connection of precast concrete frame buildings are proposed by using equal-dissipated energy capacity. It was shown that the strength of the buildings as well as their displacement capacities decreased with the decrease of either the strength or stiffness in the connections. Therefore such changes also require reductions in the response modification factors for such buildings. However, if the precast concrete frame building has plastic hinging in the connection, and has a more ductile connection than the monolithic frame building, then no reduction in R may be necessary. The deformation demand required of the connection to achieve that condition is evaluated and a simple relation is suggested in the paper.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.111-116
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• 2011

Consumers demand an increasing variety of requirements for the residential space as the quality of life improves. However, many apartment buildings with the bearing wall structure cannot meet such demands in Korea. A lot of construction resources are squandered and wastes are created as this type of residential buildings is reconstructed. The life of apartment buildings needs to be extended on the basis of easy remodeling of internal space in order to overcome the limits of the bearing wall structure. This research project aims to propose the Rahmen composite frame concept for the long life of apartment buildings. The Rahmen composite frame is expected to have better structural performance, constructability and economic feasibility than the bearing wall structure.

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.89-100
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• 2014

Energy consumption statistics in 2005 from the Korea Energy Management Corporation show that building energy usage was about 24.2% of total domestic energy consumption, and 64% of total building energy usage was consumed by residential buildings. Thus, about 10% of total domestic energy consumption is due to the heating of residential buildings. Building energy can be calculated by the configuration of the building envelope and the rate of infiltration (the volume of the infiltration of outdoor air and the leakage of indoor air), and by doing so, the annual energy usage for heating and cooling. Therefore, air-tightness is an important factor in building energy conservation. This investigate air infiltration and various factors that decrease it in timber frame buildings and suggest ways to improve air-tightness for several structural types. Timber frame buildings can be classified into light frame, post and beam, and log house. Post and beam includes Han-ok (a Korean traditional building). Six light frame buildings, three post and beam buildings, one Korean traditional Han-ok and a log house were selected as specimens. Blower door tests were performed following ASTM E779-03. The light frame buildings showed the highest air-tightness, followed by post and beam structures, and last, log houses.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.1
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• pp.1-9
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• 2021

Most commercial buildings among existing RC buildings in Korea have a multi-story wall-frame structure where RC shear wall is commonly used as its core at stairways or elevators. The members of the existing middle and low-rise wall-frame buildings are likely arranged in ordinary details considering building occupancy, and the importance and difficulty of member design. This is because there are few limitations, considerations, and financial burdens on the code for designing members with ordinary details. Compared with the intermediate or unique details, the ductility and overstrength are insufficient. Furthermore, the behavior of the member can be shear-dominated. Since shear failure in vertical members can cause a collapse of the entire structure, nonlinear characteristics such as shear strength and stiffness deterioration should be adequately reflected in the analysis model. With this background, an 8-story RC wall-frame building was designed as a building frame system with ordinary shear walls, and the effect of reflecting the shear failure mode of columns and walls on the collapse mechanism was investigated. As a result, the shear failure mode effect on the collapse mechanism was evident in walls, not columns. Consequently, it is recommended that the shear behavior characteristics of walls are explicitly considered in the analysis of wall-frame buildings with ordinary details.

• Earthquakes and Structures
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• v.15 no.4
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• pp.383-393
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• 2018

In this study, seismic performance of low and medium-rise RC buildings with wide-beam and ribbed-slab were evaluated numerically. Moment resisting systems consisting of moment and dual frame were selected as structural system of the buildings. Sufficiency of moment resisting wide-beam frames designed with high ductility requirements were evaluated. Upon necessity frames were stiffen with shear-walls. The buildings were designed in accordance with the Turkish Earthquake Code (TEC 2007) and were evaluated by using the strain-based nonlinear static method specified in TEC. Second order (P-delta) effects on the lateral load capacity of the buildings were also assessed in the study. The results indicated that the predicted seismic performances were achieved for the low-rise (4-story) building with the high ductility requirements. However, the moment resisting frame with high ductility was not adequate for the medium-rise building. Addition of sufficient amount of shear-walls to the system proved to be efficient way of providing the target performance of structure.

• Computers and Concrete
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• v.13 no.2
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• pp.271-290
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• 2014

In this study, structural irregularities in plan, which has a considerable effect on earthquake behavior of buildings, have been investigated in detail based on Turkish Earthquake Code 2007. The study consists of six main parametric models and a total of 144 sub-models that are grouped based on RC structural systems such as frame, frame + rigid core, frame with shear wall, and frame with shear wall + rigid core. All models are designed to have both symmetrical plan geometry and regular rigidity distribution. Changes in the earthquake behavior of buildings were evaluated according to the number of storeys, number of axes and the configuration of structural elements. Many findings are obtained and assessed as a result of the analysis for each structural irregularity. The study shows that structural irregularities can be observed in completely symmetric buildings in terms of plan geometry and rigidity distribution.

• Steel and Composite Structures
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• v.22 no.2
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• pp.235-255
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• 2016

This paper experimentally investigated the behavior of steel frame structures of traditional-style buildings subjected to combined constant axial load and reversed lateral cyclic loading conditions. The low cyclic reversed loading test was carried out on a 1/2 model of a traditional-style steel frame. The failure process and failure mode of the structure were observed. The mechanical behaviors of the steel frame, including hysteretic behaviors, order of plastic hinges, load-displacement curve, characteristic loads and corresponding displacements, ductility, energy dissipation capacity, and stiffness degradation were analyzed. Test results showed that the Dou-Gong component (a special construct in traditional-style buildings) in steel frame structures acted as the first seismic line under the action of horizontal loads, the plastic hinges at the beam end developed sufficiently and satisfied the Chinese Seismic Design Principle of "strong columns-weak beams, strong joints-weak members". The pinching phenomenon of hysteretic loops occurred and it changed into Z-shape, indicating shear-slip property. The stiffness degradation of the structure was significant at the early stage of the loading. When failure, the ultimate elastic-plastic interlayer displacement angle was 1/20, which indicated high collapse resistance capacity of the steel frame. Furthermore, the finite element analysis was conducted to simulate the behavior of traditional-style frame structure. Test results agreed well with the results of the finite element analysis.

• Coupled systems mechanics
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• v.2 no.2
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• pp.175-190
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• 2013

Pounding damage has been observed frequently in major earthquakes in the form of aesthetic, minor or major structural cracks and collapse of buildings. Studies have identified a building located at one end of a row of buildings as very vulnerable to pounding damage, while buildings in the interior of the same row are assumed to be safer. This study presents the results of a shake table investigation of pounding between two and three buildings in a row. Two steel portal frames, one stiffer and another more flexible, were subjected to pounding against a frame with eight other configurations. Three pounding arrangements were considered, i.e., the reference frame (1) on the right of the second frame, (2) in the middle of two identical frames, and (3) on the right of two identical frames. Zero seismic gap was adopted for all tests. Five different ground motions are applied from both directions (right to left and left to right). The amplification of the maximum deflection due to pounding was calculated for each configuration. The results showed that, for the stiffer building in a row, row building pounding is more hazardous than pounding between only two buildings. The location of the stiffer frame, whether at the end or the middle of the row, did not have much effect on the degree of amplification observed. Additionally, for all cases considered, pounding caused less amplification for stronger ground motions, i.e., the ground motions that produced higher maximum deflection without pounding than other ground motions.