Yu Z.,East China Architectural Design and Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures
The main structure of the World Expo Cultural Center consists of 36 cantilever trusses of varying span and inner frames. Static load is the primary load case of such a structure. Effective control of the deformation of the end of truss and reduction of the force of the truss and inner frame are the focus during the structural design. The load bearing feature of the structure was analyzed and the key components was strengthened correspondingly. Firstly, two circumferential frame beams on the top of the column were designed with steel rectangular tube; secondly, slab of the sixth floor was thickened to 200mm and steel plate was welded between the first panel of the cantilever truss. These measures put a 'tight restriction' on the top of 36 cantilever trusses and significantly reduced the deformation of the end of truss and the force of main members. Dynamic analysis shows that the vibration characteristics of the structure are different from normal tall buildings. As for this structure, torsion is the first modal shape, but lateral stiffness of the structure is very strong, lateral force resisting components are evenly distributed and the frame is made of steel so that brittle failure is not easy to occur when the structure suffering horizontal earthquake. In order to study the influence of floor stiffness, three models of calculating real floor stiffness, without floor stiffness and only single frame were respectively analyzed and the differences of the force of main components were studied in details. The results indicate that floor stiffness has a significant influence on the force of main members but the influence is different. So that the envelope results of the above three models are all considered during the design course. Source
Liu R.-B.,East China Architectural Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering
The Shanghai Caoxi Road Station Plot Public Open Space Project is located in the downtown of Shanghai City. The excavation is adjacent to several city roads, pipelines, elevated road, light rail line and station. Protection requirements of the surrounding facilities are quite high, especially for the large-diameter sewage pipes at the north side of the excavation. The general situation of the project and the overall design scheme of the deep excavation are introduced. Emphasis is put on the technical countermeasures of protecting the large-diameter sewage pipes, including constructing the bored piles in the cement mixing soil, using elevated soil conveying path, and tracing grouting. The monitoring results show that the surrounding environments are effectively protected by the adopted supporting system and technical countermeasures. The successful construction of the deep excavation creats favorable conditions for the construction of the main structures of the project. Source
Huang M.,Tongji University |
Wang W.,East China Architectural Design and Research Institute Co. |
Zheng G.,Tianjin University
Tumu Gongcheng Xuebao/China Civil Engineering Journal
The status of the research on underground engineering in soft soils are reviewed. Three types of key issues in deep excavations and shield tunnelling are discussed. The first one is concerned with the new methods and technilogies for deep excavations in soft soils under complicated geological and environmental conditions, such as the stress analysis of retaining structures for foundation pits, basal stability analysis of excavations, the influence of seepage on the stability of deep excavation, the redundancy of deep excavations, and the new technique of excavations in soft soils. The second one focuses on the stability and deformation analysis of tunnel in soft soils, including the stability analysis of tunnel face, the influence of seepage on the stability, the longitudinal differential settlement and the long-term settlement of tunnel, theoretical analysis and model test of the seismic response of tunnel. The last one involves the ground deformation induced by deep excavation and tunneling, and the environmental influences from underground construction. Source
Wang D.,East China Architectural Design and Research Institute Co. |
Zhou J.,East China Architectural Design and Research Institute Co.
Jianzhu Jiegou Xuebao/Journal of Building Structures
Hybrid high-rise building structure has both the advantages of steel structure and concrete structure. Steel and concrete hybrid structures are widely used in China in recent years. However, different views exist related to the seismic behavior of hybrid structures and key design methodologies. This paper attempts to summarize various hybrid structure systems along with introduction of typical engineering examples. Key technical issues are discussed, including seismic behavior, ductility design, member design, the reliability of connections, difference in vertical deformation, construction analysis, nonlinear time-history analysis and damping ratio. Future research needs are also suggested. Source
Wang J.H.,Shanghai JiaoTong University |
Xu Z.H.,East China Architectural Design and Research Institute Co. |
Wang W.D.,East China Architectural Design and Research Institute Co.
Journal of Geotechnical and Geoenvironmental Engineering
An extensive database of 300 case histories of wall displacements and ground settlements due to deep excavations in Shanghai soft soils were collected and analyzed. The mean values of the maximum lateral displacements of walls constructed by the top-down method, walls constructed by the bottom-up method (including diaphragm walls, contiguous pile walls, and compound deep soil mixing walls), sheet pile walls, compound soil nail walls, and deep soil mixing walls are 0.27%H, 0.4%H, 1.5%H, 0.55%H, and 0.91%H, respectively, where H is the excavation depth. The mean value of the maximum ground surface settlement is 0.42%H. The settlement influence zone reaches to a distance of about 1.5H to 3.5H from the excavation. The ratio between the maximum ground surface settlement and the maximum lateral displacement of a wall generally ranges from 0.4 to 2.0, with an average value of 0.9. The factors affecting the deformation of the wall were analyzed. It shows that there is a slight evidence of a trend for decreasing wall displacement with increasing system stiffness and the factor of safety against basal heave. Wall and ground movements were also compared with that observed in worldwide case histories. © 2010 ASCE. Source