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Guo T.,Nanjing Southeast University | Xu W.,Nanjing Southeast University | Song L.,Nanjing Southeast University | Wei L.,Jiangsu Hongji Science and Technology Co.
Journal of Performance of Constructed Facilities | Year: 2014

Recent large earthquakes in China (e.g., Wenchuan earthquake and Yushu earthquake) resulted in enormous damage to school buildings and took many students' lives. Recognizing the seismic vulnerability of existing school buildings, the Chinese government started a nationwide mission in 2009, aiming at increasing the seismic capacity of school buildings through inspection and retrofit activities. This paper presents the experiences of the authors in the retrofits of school buildings in which seismic isolation by using rubber and/or sliding bearings was adopted as a new and efficient retrofit technique, as compared with conventional ones. The retrofitted school buildings include masonry buildings, RC frame buildings, and a mixture of both. Design methods and the corresponding requirements in the modified seismic design code are presented, and typical construction procedures of the seismic retrofit are summarized from an engineer's point of view. Procedures regarding the contract and review of the retrofit projects are also introduced. To this end, a case study is made to demonstrate the proposed design and construction methods. The presented work provides references to the seismic retrofit of existing buildings. © 2014 American Society of Civil Engineers.

Du Y.,Nanjing Southeast University | Liu S.,Nanjing Southeast University | Qin X.,Nanjing Southeast University | Wei M.,Nanjing Southeast University | And 2 more authors.
Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) | Year: 2014

A comparison of the physico-chemical properties of calcium carbide residues (CCR) and quicklime suggests that over-wet clayey soils stabilized by CCR is potentially used as highway subgrade materials. A field investigation on the mechanical performance of the CCR stabilized over-wet clayey soils is conducted. The effects of the curing time on the California bearing ratio (CBR), the resilient modulus (Mr), the penetration resistance (Rs), and the dynamic cone penetration index (DCPI) of the CCR and quicklime stabilized soils are discussed. The results show that the CCR exhibit larger specific surface area and higher fine-particle content than the quicklime, which is more in favor of the evolution of pozzolanic reactions between the binder (i.e., CCR or quicklime) and soils. Compared with the quicklime stabilized soils, the CCR stabilized soils have greater performance in terms of higher CBR, greater resilient modulus and penetration resistance, and higher degree of correlation between DCPI and CBR and that between DCPI and Mr. In addition, CCR has evident benefits in terms of its cost-effectiveness, no dust pollution and little CO2 emission during the construction. It is concluded that CCR is a viable, economical, and environmental-friendly binder in stabilizing over-wet clayey soils, which are used as subgrade materials.

Guo T.,Nanjing Southeast University | Xu J.,Jiangsu Hongji Science and Technology Co. | Xu W.,Nanjing Southeast University | Di Z.,Nanjing Southeast University
Journal of Performance of Constructed Facilities | Year: 2015

Existing structures may be in need of seismic upgrading owing to structural deterioration, change in function or use, increased performance requirements, or modified seismic codes. In recent years, fluid viscous (FV) dampers have received increasing attention because of their notable seismic-reduction capacity and easy installation. This paper outlines the design procedure of seismic upgrading of existing buildings using FV dampers. Discussions are made on some key issues for seismic upgrading using FV dampers, including the analytical damper-brace model under large earthquakes and strategies for damper layout. A case study is made, in which a 21-story hotel built in 1991 was seismic upgraded. One special feature of this project is that only the first six stories can be structurally modified, resulting in limitations on the damper layout. According to the proposed design procedure, 56 FV dampers are suggested for this project, which provide a supplemental damping ratio of 5.3%. As a result, the seismic responses of upper stories could be significantly reduced, which avoids damaging the decoration of the building above its sixth story and enables short and economic construction. © 2014 American Society of Civil Engineers.

Yong-Zhan C.,Nanjing Urban Construction Investment Holding | Ju-Wei Y.,Jiangsu Hongji Science and Technology Co. | Bang-Bin S.,Civil Defense Bureau of huaiAn | Bing Y.,Civil Defense Bureau of huaiAn
Proceedings - 7th International Conference on Intelligent Computation Technology and Automation, ICICTA 2014 | Year: 2015

With a foundation pit engineering example, layout principles and design method of multi-ring bracing system in the foundation pit are discussed, while the stiffness formula is supposed for design of retaining and protection structure. The calculate results are compared with measured data. It is indicated that circular strut system has good adaptability in deep foundation pit with irregular shape, and the suggested method can be used in similar engineering. © 2014 IEEE.

Guo T.,Nanjing Southeast University | Wu E.,Hohai University | Li A.,Nanjing Southeast University | Wei L.,Jiangsu Hongji Science and Technology Co. | Li X.,Hohai University
Journal of Performance of Constructed Facilities | Year: 2012

This paper presents the integral lifting and seismic isolation retrofit of the great hall of Nanjing Museum, a 78-year-old cultural and historical building. Due to the need for extension, the great hall of the Nanjing Museum needed to be lifted 3.0 m. The total building area for lifting was 4,830 m2, with a total of 161 lifting points, which made this project quite challenging and also the largest done to date. Moreover, seismic isolation retrofit was utilized to improve the seismic performance of the translocated building. Details of the integral lifting and the seismic retrofit are presented in this paper, which include (1) the load underpinning system, (2) the spatial strengthening truss system, (3) the lifting control system, and (4) the base isolation using laminated rubber isolators. The entire lifting system performed well, and the main construction was finished within 5 months. Seismic time-history analyses were further performed to evaluate the effect of the seismic isolation. It was observed that the seismic responses of the museum were significantly reduced after retrofit. © 2012 American Society of Civil Engineers.

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