| PaperNO | Paper / Abstract |
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G0-020
10:50
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11:05
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A STUDY ON COMPARISON OF MODAL RESPONSE COMBINATIONS IN SEISMIC RESPONSE ANALYSIS
One of the widely used methodologies for analyzing the behavior of a structural system subjected to seismic excitation is response spectrum analysis. The maximum responses for each mode are calculated independently, and these modal responses are then combined to obtain the model's overall response. Since the peak responses in the different modes will not in general occurred at the same time, hence the maximum response should be estimated by modal combination rules. Due to the SAP2000 is widely used commercial software in civil engineering, but not all the combination methods required by U.S. NRC are included. Therefore, the purpose of this study is to create an applicable program for modal combination rules to complete response spectrum analysis. This study analyzed the algorithmic methods for the modal combination rules which are introduced by U.S. NRC, and verified the processes via SAP2000. The results of analysis were consistent with the outputs of SAP2000. Finally, this study established the computational procedures of modal combination rules and follow-up works of programming are planned.
Jia-Sheng Chiou, Yuan-Chieh Wu
Modal Combination Rules, Nuclear Regulation, Response Spectrum Analysis
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G0-014
11:05
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11:20
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SIMPLIFIED SEISMIC ANALYSIS OF BUILDINGS WITH SETBACKS
Vertically irregular buildings with strong or stiff-and-strong lower stories such as setback buildings are common in engineering practice. However, besides a sophisticated nonlinear response history analysis, there seems to be no simplified seismic analysis method suitable for this type of building. Thus, this study explores a two-degree-of-freedom (2DOF) modal system for representing each vibration mode of such buildings. The upper and lower degrees of the 2DOF modal system respectively simulate the modal responses of the two distinct parts (i.e., the upper stories and the lower stories) of a building with strong or stiff-and-strong lower stories. Instead of a conventional single degree-of-freedom modal system, the 2DOF modal system is employed in the modal response history analysis of buildings with the specific vertical irregularities. The effectiveness of the proposed seismic analysis method is verified by investigating four 9-story and four 20-story buildings, which have the lower stories stronger or stiffer-and-stronger than the upper stories. Each of the eight example buildings is subjected to three ensembles of ground motion records.
Chih-Chia Tsaur, Jui-Liang Lin, Keh-Chyuan Tsai
modal response history analysis, modal system, pushover analysis, setback buildings, vertically irregular buildings
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G0-021
11:20
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11:35
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RETROFITTING METHOD WITH COMPRESSION BRACE WITH SELF-JOINTING DEVICE FOR RC STRUCTURE
Taiwan locates on the Pacific Seismic Belt, buildings are often challenged by earthquakes. Hence, the seismic capacity of the building is very important to protect the resident’s safety and properties. The current seismic code is stricter than the early code, therefore the seismic capacity of buildings which were built before the current code may not satisfy the requirement. The conventional retrofitting method, such as reinforced concrete column jacketing, added wing walls, infilled reinforced concrete walls and infilled masonry walls and so forth. These methods effectively improve the lateral strength of the buildings. However, the disadvantages of the conventional retrofitting method are not only a long construction period but also create a lot of noise and dust during the construction. These will not be accepted by residents, as well as become an obstacle for improving seismic capacity. This study introduces a new retrofitting method which is easy construction, short construction period and less interference. Through the series experiments, like member test, static cyclic test, and dynamic experiment, it can illustrate the benefits and feasibility of the proposed method.
RenJie Tsai, ShyhJiann Hwang, FuPei Hsaio, WenChen Shen, PuWen Weng
compression brace, pre-stress device, Retrofitting method, self-jointing
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G0-023
11:35
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11:50
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ANALYSIS MODEL OF LATERAL LOAD-DISPLACEMENT CURVE OF RC WALL WITH OPENINGS UNDER SHEAR FAILURE
Residential buildings in Taiwan consist of many reinforced concrete (RC) walls with openings which are meant for functions like ventilation, lighting, aisle and so on. These walls provide lateral stiffness and strength to the structure. However, their contribution has usually been neglected while assessing the seismic capacity of the building due to complex transfer mechanism. This study introduces an analysis model of the lateral load-displacement curve of RC walls with openings under shear failure which has significant force transfer mechanism. The proposed analysis model is applicable for the openings which cause a weak area in vertical members, like vertical wall segment, wall pier, and boundary column. The force transfer mechanism can be established through springs in series and parallel theory. Hence, not only the complex transfer mechanism can be simplified, but also the lateral load-displacement curve can be established by the proposed model.This study compares the results of experiments and predictions, which indicate the analysis results are reasonable and conservative. The proposed model can let engineers either comprehend the force transfer mechanism or apply on the practice.
RenJie Tsai, ChienChuang Tseng, ShyhJiann Hwang
analysis model, Openings, reinforced concrete, shear wall
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G3-012
11:50
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12:05
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FRACTURE ASSESSMENT OF ELECTRO-SLAG WELDING CONNECTION IN STEEL BEAM-TO-BOX COLUMN JOINTS
Steel box columns are widely used in steel building structures in Taiwan due to the strong axes in two directions. Diaphragm plates of the same thickness and elevations as beam flanges are usually welded inside box column to transfer the beam end moment to column. Electro-slag welding (ESW) process is typically used in attaching the diaphragms to column flanges. This ESW process has been widely used in steel beam-to-box column joints in Taiwan because of its’ convenience and efficiency. However, ESW may increase the hardness of the welds and heat affected zones (HAZs), while reduce the Charpy-V Notch strength in HAZ. This situation could cause the diaphragm to column flange weld to suffer premature fracture before a large plastic rotation is developed in beam-to-box column joints. In order to quantify the critical eccentricity and the effectiveness of predicting the fractures, this study utilizes the fracture prediction model and finite element model (FEM) analysis to correlate the test results. In this study, three beam-to-box column connection subassembly tests have been conducted with a different loading protocol or the shape of ESW chamber. Test results show that the fracture instances can be predicted based on the cumulative plastic deformation in the HAZs. Tests confirm that the possible fracture of the diaphragm to column flange welds can be mitigated by enlarging the chamber of the ESW. When the fracture prediction model is applied, the material parameters were firstly established from the Circumferential Notched Tensile (CNT) tests and FEM analysis. Subsequently, these parameters were used to predict the fractures observed in the beam-to-box column connection subassembly tests. The fracture locations and instances can be reasonably well predicted by a suitable FEM model analysis. Thus, the effectiveness of CNT and the fracture model are confirmed.
Keh-Chyuan Tsai, Ching-Yi Tsai, Chung-Che Wu, Chao-Hsien Li
circumferential notched tensile test, electro-slag welding, finite element model analysis, fracture prediction model, heat affected zone, steel beam-to-box column connection
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