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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 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.

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.

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.

Xu J.,Jiangsu Hongji Science and Technology Co. | Chen Y.,Nanjing Urban Construction Investment Holding | Guo T.,Jiangsu Hongji Science and Technology Co. | Di Z.,Jiangsu Hongji Science and Technology Co.
Proceedings - 7th International Conference on Intelligent Computation Technology and Automation, ICICTA 2014 | Year: 2015

Historic buildings are in need of careful protection because they are the symbols of regional culture and artistry. On the other hand, utilization of underground space is a trend in modern urban development, which sometimes brings challenge to the protection of historic buildings. In this paper, the need for building translocation is presented, and a case study is made on the protection of a historic building (i.e. The former Young Men's Christian Association building), in which the building was temperately translocated onto the support system of the deep foundation pit and was moved back after the construction of neighboring basement. © 2014 IEEE.

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.

Yuan J.-W.,Hohai University | Yuan J.-W.,Jiangsu Hongji Science and Technology Co. | Du C.-B.,Hohai University | Liu Z.-M.,Hohai University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2011

Here, the time-domain calculating method for dynamic interaction between gravity dam and foundation object to obliquely incident and seismic waves was developed based on hypothesis of homogeneous foundation, in which both oblique plane SV wave and oblique plane P wave were input simultaneously at artificial boundary and produced similar seismic response to that of the design seismic component at surface of half space. According to theory of wave propagating in solid, both incidence angles and amplitudes of the oblique waves had deterministic relation. Taking the interaction between gravity dam and foundation as an example, its time-domain seismic response was calculated and analyzed. The preliminary results showed that obliquely incident and seismic waves have greater influence on the area near the interface of dam and foundation, where the dynamic response to obliquely incident and seismic waves is larger than that to vertically incident and seismic waves. The method took both design seismic component and radiation damping of foundation into account, and produced nonuniform motion at interface of dam and foundation, so it could be used to study dynamic response of a structure under nonuniform input.

Jiang S.,Hohai University | Du C.,Hohai University | Yuan J.,Jiangsu Hongji Science and Technology Company
Science China Technological Sciences | Year: 2011

In the paper, the added tangential nonlinear springs are introduced to represent the effects of one-way and two-way shear keys. The added tangential stiffness coefficient is relative to the joint opening and the relative tangential movement and determined numerically by using a refined model of shear keys. The user subroutine of nonlinear spring elements has been implemented into ABAQUS program. The seismic responses of an arch-gravity dam are mainly examined. It is shown by the results that a significant increase of about 17%-30% in joint opening can be observed for the dam with one-way shear keys; the two-way shear keys are beneficial to restrain the sliding displacement along both the radial and vertical directions, whereas the one-way shear keys mainly restrain the displacement along the radial direction; for the dam with shear keys, the maximum arch stress is increased, the cantilever stress is reduced, and the location of the maximum cantilever stress is also moved from the dam heel to the midheight of the cantilever. © Science China Press and Springer-Verlag Berlin Heidelberg 2011.

Guo T.,Nanjing Southeast University | Guo T.,South China University of Technology | Li A.,Nanjing Southeast University | Wei L.,Jiangsu Hongji Science and Technology Co. | Gu Y.,Nanjing Southeast University
Journal of Performance of Constructed Facilities | Year: 2013

This case study presents the horizontal translocation of the Hongxing Mansion, a high-rise building in China, which was moved transversally for 26 m because of modifications in urban planning. The 13-story RC frame-wall structure was built in 2002 with a total height of 63.2 m and a total weight of 109,881 kN, making the project unique as compared with other similar cases. The executive process of this project is introduced, including the initial planning, design, and construction procedures. A load underpinning system was proposed that can transfer the vertical loads uniformly to the rails and distribute the propelling loads from the loaded end to the other end of the building. Anchor-jacked piles were used at the original foundation from the limited indoor clear height so that rails in the original basement can be well supported without the need of large piling machines. A special moving system was proposed and successfully applied, which combined the advantages of pull and push, so that the efficiency and stability of moving were guaranteed. The removable reaction frames were used to alleviate the energy accumulation in tendons and the sudden energy release when the building started to move. Finally, the columns and walls were connected with the new foundation without diminishing their seismic capacities. The design and construction methods in this project provide references to buildings in need of translocation. © 2013 American Society of Civil Engineers.

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