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SE2-017
14:00
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14:15
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SEISMIC PERFORMANCE OF NON-DUCTILE RC FRAME RETROFITTED USING POST-INSTALLED RC WALL
Reinforced Concrete (RC) frame structures that were designed and built according to older standards can be damaged during destructive earthquakes as a result of insufficient lateral strength and/or deformation capacity. Such structures must be retrofitted to satisfy the current requirements and to survive future earthquakes. Owing to its high lateral strength and stiffness capacity of an RC wall, the post-installation of an RC wall in a non-ductile frame for retrofit is a widely used retrofitting technique. However, for frame structures with low-strength concrete, the typically used connected construction method on the interface between existing and new concrete may be not able to provide effective force transfer, and may cause unexpected brittle failure in the retrofitted structure. Such unexpected brittle failure may reduce the seismic capacity of the structure and threaten its safety. Therefore, in this experimental investigation, two retrofitting methods that use a post-installed RC wall are proposed to improve the load transfer mechanism on the interface. The first involves a wall with diagonal rebar and boundary spirals, and the second involves a wall with an additional inner frame. Reversed cyclic loading is used to test the seismic capacity of the specimens. The test results indicate that the proposed new retrofitting methods can effectively improve the performance of the retrofitted structure. Finally, post-embedded piezoceramic-based sensors were used to monitor the structural health and detect interface damage of the specimens during the test. The experimental results demonstrate the effectiveness of the piezoceramic-based approach to structural health monitoring and the ability of the method to locate damage in shear governed RC structures under seismic loading.
Fu-Pei Hsiao, Wen-I Liao, Zi-En Gu
concrete frame, health monitoring, piezoceramic-based sensor, RC wall, retrofit
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SE2-032
14:15
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14:30
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SEISMIC UPGRADING OF SCHOOL BUILDINGS SINCE 1999 CHI-CHI EARTHQUAKE
The reconnaissance reports of the 1999 Chi-Chi earthquake revealed that elementary and high school buildings are the particularly vulnerable structures in Taiwan. Therefore, enhancements to the seismic capacities of the school buildings through retrofitting are urgently required. However, there are 3,621 elementary and high schools in Taiwan, and the total number of buildings is as high as twenty seven thousand. Without careful planning, the budget could easily be exceeded due to the large number of buildings. Adopting an effective strategy using economical technologies and systematic prioritization is essential for this school retrofitting project to be successful. The government of Taiwan has launched a project to upgrade the seismic performance of school buildings. Under this project, more than five thousand school buildings have been retrofitted. School buildings with high seismic risk have been upgraded seismically. In the Meinong and Hwalien earthquakes occurred on February three and one years ago, respectively, no damage was found from school buildings after retrofitted and only medium damage was found in several school buildings without retrofit. The seismic performance of school buildings has been greatly improved. The objective of this paper is to report on the strategy, technology, and progress of this seismic project for school buildings in Taiwan.
Lap-Loi Chung, Shyh-Jiann Hwang
1999 Chi-Chi Earthquake, evaluation and retrofit, school buildings, seismic upgrading
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SE2-030
14:30
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14:45
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SEISMIC RETROFIT IN STAGES FOR RESIDENTIAL BUILDINGS WITH SOFT AND WEAK BOTTOM STORY
Many commercial and residential mixed buildings collapsed in 1999 Chi-Chi Earthquake due to the soft and weak bottom story. In the traditional mixed buildings, the open area, such as shop stores and living rooms, were designed in the ground floor, however, the private area, such as residential bedrooms and bathrooms were usually designed in the upper floors. The open area is usually few partition walls, however, the private area needs lots of partition walls. Therefore, the structural system with soft and weak bottom story is a significant problem of the traditional mixed buildings. Rebuild and seismic retrofit of the existing mixed buildings always has a big challenge because it is very difficult to come out with agreement from the multi-owners of the buildings. However, the occurrence of earthquakes is unpredictable, the seismic capacity of existing buildings should be improved as soon as possible. Therefore, seismic retrofitting in stages may be a feasible strategy. The study proposed the seismic retrofit in stages can implement retrofit in the public area without affect into private area. That may be easier to come out with agreement of whole multi-owners. The proposed seismic retrofit in stages aims to improve the problem of soft and weak bottom story. The first phase of retrofit aims to reduce the collapsed probability of the buildings although that may not satisfy the seismic performance of the current seismic design code. The final phase shall still implement retrofit of whole buildings which can satisfy the seismic performance of the current seismic design code. This paper introduces a design procedure of the seismic retrofitting in stages for the existing reinforced concrete buildings with soft and weak bottom story. Moreover, a design example will be provided.
Lap-Loi Chung, Shyh-Jiann Hwang, Tsung-Chih Chiou, Yu-Heng Lin
1999 Chi-Chi Earthquake, residential buildings, seismic retrofit in stages, soft and weak bottom story
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