Vol.32/No.4 (128) (2017)
| Title | Study on the Shear Behavior of Chemical Anchors in the Low Strength Concrete |
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| Author | Jia-MingHsu, Yuan-Liang Zheng, Fu-Pei Hsiao, Wen-I Liao, Pu-Wen Weng, Tai-Kuang Lee, Guo-Luen Huang |
| Keywords | low strength concrete, adhesive anchors, post-installed rebars, shear, retrofit |
| Abstract | In order to increase seismic capability of structural system, retrofit techniques are usually applied. Traditional RC retrofit methods include adding RC shear wall, wing wall and RC jacketing. In addition to connect new structural members to old structural members,adhesive anchors (post-installed rebars) are used. From the investigation results by National Center for Research on Earthquake Engineering (NCREE), it was found that concrete strength of old school buildings is very low due to poor construction quality. Therefore, the behavior of post-installed rebars in low strength concrete is very important. In this study, the concrete strength of specimens are 5MPa, 10MPa and 15MPa.According to the minimum edge distance and depth of ACI code, this study proposed a series of anchorage and shear test, a total of 192 specimens. Control parameters are the embedded depth of the rebar, the distance to edge, and concrete strength. The results of those experiments are compared with the calculated values of ACI code. It was found ACI calculated values remain conservative in strength 10MPa and 15MPa, but in the 5MPa calculated values is very close to experiment results.So,the formula of ACI code used in low strength concrete may not be conservative. From the experiments of this study,it was also found a new failure mode as steel bending failure. Finally, the importance of the shear strength of the interface between the post-installed rebar and concrete was addressed with an actual experiment of RC shear wall and the results of the reconnaissance of earthquake disaster in Taiwan. |
| Title | Loading Test Analysis of An Earthquake-Damaged Bridge |
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| Author | Chun-Chung Chen, Yu-Chi Sung, Zheng-Kuan Lee, Chia-Chung Hsu, Fang-Yao Yeh, Yu-Chi Sung, Feng-Kai Chang, Yi-Tsung Chiu, Ping-Hsun Huang, Jia-Ying Chen, Wan-Long Wu |
| Keywords | Gene Algorithm, Response Surface Method, Loading Test |
| Abstract | This paper conducts an analysis on loading tests of the earthquake-damaged bridge. The study uses the commercial finite element program to build a bridge analytical model, and the analysis result is compared with that of the field load testing to verify the proposed model. Generally, in order to improve the reliability of the finite element model, it is needed to adjust some modeling parameters using field experimental data to realize the representative characteristic of the bridge structure. However, the structural model usually involves numerous elements which lead the poor analysis efficiency of modeling parameters adjustment work. In view of this, this study applies the response method of experimental design function to take place of the finite element model by statistical experimental design theory and integrates the genetic algorithm to optimize modeling parameters which were used in the model and can make the model gives the reliable results which close to static and dynamic characteristics of the actual bridge. |
| Title | Study and Establishment for Cloud Platform of Preliminary Seismic Evaluation of Reinforced Concrete Buildings |
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| Author | Yu-Chi Sung, Ming-Chun Lai, Yi-Tsung Chiu, Chun-Jung Chen, Hong-Syuan Lin, Chih-Liang Yen, I-Chau Tsai, Chien-Jung Chen, Chang-Yu Chen |
| Keywords | Cloud Operation System, Quantitative Evaluation, Disaster Prevention |
| Abstract | The numerous existing buildings maynot behave qualified seismic performance satisfied with the current seismic design code as a result of material deterioration or outdated design, etc. It needs a significant cost and time to do the detailed seismic evaluation of existing buildings for determination on necessary seismic retrofit. Therefore, development of a preliminary seismic evaluation system giving a rapid and reliable result is very important currently in Taiwan. This paper focused on developing the preliminary seismic evaluation of reinforced concrete buildings (PSERCB), based on research of Profs. Tsai and Sung 2014, granted by Architect Research Institute, Taiwan. Both qualitative and quantitative evaluation results are involved in this framework. A cloud platform was established for the engineers to input the inspection of current status of buildings and the evaluation report is able to be downloaded as technical report. All the data on the cloud platform are collected as the basis of big data analysis for strategy of disaster prevention to government in the future. |
| Title | A Simplified Seismic Analysis Procedure for Vertically Irregular Buildings |
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| Author | Chih-Chia Tsaur, Jui-Liang Lin, Keh-Chyuan Tsai |
| Keywords | vertically irregular building, setbacks, nonlinear response history analysis, modal pushover analysis, modal response history analysis |
| Abstract | Most seismic building design codes describe the features of vertically irregular buildings. In addition, these building design codes prescribe that dynamic analysis should be adopted in the seismic analysis and design of these irregular structures. Besides the finite element method (FEM), which performs inelastic dynamic analysis to complete finite element models, the modal pushover analysis (MPA) method is one of common simplified seismic analysis procedures. The force-deformation relationship of each vibration mode obtained from the MPA method is employed to construct the corresponding single-degree-of-freedom (SDOF) modal system. The modal response histories are obtained from performing nonlinear response history analysis to each SDOF modal system. The total seismic responses of the building are estimated by adding up the seismic response histories resulting from all vibration modes. This study designates the aforementioned simplified method as the single-degree-of-freedom modal analysis method (SDM). Some research literatures showed that using SDM leads to overestimated seismic responses of the lower parts of the vertically irregular buildings, which have stronger or stronger-and-stiffer bottom story or lower half. Instead of the SDM, the complicated and time-consuming FEM was thus suggested for the seismic analysis of this type of buildings. Nevertheless, this type of vertically irregular buildings is common. It would benefit engineering practice if there are simplified seismic analysis methods available to this type of irregular buildings. In light of the incompetence of using the SDOF modal systems to simultaneously reflect the seismic responses of the super- and sub-structures of the buildings, this study proposes the two-degree-of-freedom modal analysis method (2DM). 2DM is basically the same as SDM, except that 2DM represents each vibration mode as a two-degree-of-freedom modal system. One 9-story and one 20-story regular moment resisting frames are selected as the prototype building in this study. Each of the two prototype buildings are further varied into four vertically irregular buildings as the target buildings. The four variations include buildings with stronger, stronger-and-stiffer first story; stronger, stronger-and-stiffer lower half. FEM, SDM, and 2DM are applied to the eight target buildings subjected to the selected 60 ground motions. This study shows that the analysis results obtained from 2DM are the same as those obtained from SDM as long as the structures remain elastic. While the structures become inelastic, 2DM generally results in more accurate estimations of inter-story drifts, compared with those obtained from SDM. The overestimated peak inter-story drifts of the substructures by using SDM are effectively reduced by using 2DM. |
| Title | Interference Effects on High-rise Building Based on Aerodynamic and Aeroelastic Tests |
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| Author | Yuan-Lung Lo, Chi-Rou Chen |
| Keywords | High-rise building, Aero-elastic test, Interference effect, Interference factor |
| Abstract | Wind effects on high-rise buildings are one of the most important topics in safety designs of structures, especially the target building is neighbored by another or even multiple high-rise buildings. This study intends to compare the differences between the results from the aerodynamic test and the results from the aeroelastic test. Physical scaling tests are planned in three parts: firstly the aerodynamic test is conducted in order to understand mean and fluctuating force coefficients of a square prism model with interference effects; secondly the aeroelastic test is conducted in order to examine the displacement variation under various velocities and terrain flows; thirdly the results from both tests are compared to find the differences by means of displacement estimation methodologies. It is found that, adopting the aerodynamic test for wind-induced response is not reliable compared to the aeroelastic test since the wind-induced response with/without interference effects are much more complicated and need more investigations in systematic aeroelastic test works. |