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Liu K.,Zhejiang Sci-Tech University | Xie X.,Zhejiang University | Liu H.,Hanjia Design Group of China
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2010

Rigid-flexible-pile composite foundations are a newly developed method for resisting vertical load in deep soft soil. Flexible piles are used to strengthen shallow soft soil, and rigid piles are used to reduce settlement of the foundation. A cushion below the foundation caps is used to redistribute and adjust stresses on the piles and subsoil. The soft soil can also share part of the applied load in the foundation system. This enables the rigid-flexible-pile composite foundation to resist much larger load with less settlement. This paper examines the performance of such a foundation under vertical load. The results show that the stress and load-sharing ratio of the two kinds of pile and subsoil varies with the applied loading, but most of the applied load is shared by the rigid and flexible piles. Settlement of the composite foundation is controlled well, and can satisfy the performance requirements of buildings on deep soft soil.

Jiang J.,Zhejiang University | Xu Z.-H.,Zhejiang University | Xu L.-F.,Hanjia Design Group of China
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2010

A meso-constitutive model was established in order to analyze the load and the deformation feature of granular material. The core of the model was the stability of the force chain and the kinetics. A force chain composed of three particles of different radiuses was chosen as study object. The relative tangential displacements between the particles and their rotation angles were obtained from the conditions for motor coordination and bending equilibrium by defining the displacement model between particles. Then the expression representing the load and the displacement on force chain was deduced from the energy equation of its buckling deformation according to the thermodynamic theory. Given three particles of same radiuses, the model can match the experimental results obtained by the discrete element method after contrasting and analyzing the reasonability of the model. The changes of each variable were analyzed with the changes of the radiuses of two groups of particles. Results demonstrate that the changing radiuses of particles can greatly influence the force load and the deformation feature.

Shen G.-H.,Zhejiang University | Zhang C.-S.,Hanjia Design Group of China | Sun B.-N.,Zhejiang University | Lou W.-J.,Zhejiang University
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2011

The computational fluid dynamics (CFD) methodology is employed to obtain the wind pressures on the inner surface of large hyperbolic cooling towers. The wind pressures on the inner surface of cooling tower, which are induced by the action of outer wind field and self-circulating system due to air temperature difference, are calculated numerically with the k-ε turbulence model and multiphase model, respectively. The distributions of these two parts of wind pressure with respect to height and latitude are then investigated. The resultant wind pressures on inner surface on cooling tower are obtained and their suggestive values are given. Results from this study show that the wind pressures on inner surface induced by the action of outer wind field vary significantly with heights and latitudes, whereas those induced by self-circulating system keep almost unchanged with respect to latitude. If the velocity of outer wind field is small, the wind pressure on inner surface induced by self-circulating system will occupy a certain proportion of the resultant wind pressures, while if the velocity is large, it can be neglected.

Sun X.-Y.,Zhejiang University | Dai J.-G.,Hong Kong Polytechnic University | Wang H.-L.,Zhejiang University | Xu C.,Hanjia Design Group of China
Advanced Steel Construction | Year: 2015

This paper presents an experimental study into the static and fatigue behavior of three pairs of small-scaled reinforced concrete (RC) bridge girders, in order to investigate the influences of overloading on the fatigue strengthening effects of externally bonded carbon fiber reinforced polymer (CFRP) laminates and understand the mechanisms of fatigue damage accumulation in CFRP-strengthened RC bridge girders under vehicle overloading. Two pairs were strengthened with CFRP laminates and the remained one pair was un-strengthened as references. Two types of overloading were implemented in this test program: one was overloading both prior to and after FRP strengthening and the other was cyclic overloading only after FRP strengthening. At the end of the cyclic overloading all the girders were tested under monotonic loading until failure. Through the evaluation of the pre-fatigue static strength, the development of deflection and cracks during the fatigue loading and the post-fatigue strength of both un-strengthened and CFRP-strengthened RC girders, the effects of the above two different types of overloading on their static and fatigue behaviors are extensively discussed. © 2015, Hong Kong Institute of Steel Construction. All rights reserved.

Sun X.-Y.,Zhejiang University | Xu C.,Hanjia Design Group of China | Wang H.-L.,Zhejiang University | Chu J.-F.,China State Construction Co.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2012

In order to realize accurate evaluation of the fatigue damage and failure risk for existing bridges which suffering vehicle overloading, fatigue experiments of bridge component with and without carbon fiber reinforced plastics (CFRP) reinforcement were carried out based on vehicle load survey. Three overloading states were simulated, which were general state, serious state and combine state. The capacity after overloading was tested, and the performance parameters, such as section strain, crack pattern, maximum crack width, deflection, were monitored, then the development law of above parameters versus the number of fatigue cycles under overloading were investigated. The experimental results indicate that the capacity cannot be used to refer the service performance of bridge, and a better way to reflect the overloading effect is fatigue damage, which affects the deformation capacity of the bridge structure. The section strain increases with the number of fatigue cycles under low cycle fatigue load. The plane-section assumption is still satisfied approximatively till the end of the fatigue cycle. The fatigue performance of bridge component under overloading should be evaluated using steel rebar strain and mid-span deflection as the main control indexes.

Xie X.-Y.,Zhejiang University | Wu Y.-H.,Hanjia Design Group of China | Jiang W.-D.,Hanjia Design Group of China | Wu J.,Hanjia Design Group of China | Liu K.-F.,Zhejiang Sci-Tech University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2011

Based on the design practice of a super-tall building crossing metro tunnel, a three-dimensional, elasto-plastic numerical simulation was conducted by using software ABAQUS to investigate the deformation and internal forces of piled raft foundation due to the passage of a metro tunnel. The mohr-coulmb yield criterion was adopted for soil. According to the numerical results, the experiential design was optimized. The numerical results indicate that bending moment of the raft increases due to tunnel excavation. Adjacent piles are bending towards tunnel, and the horizontal deformation of piles in front row is lager than those of rear row. In the same row, deformation of the side pile is larger than that of the middle pile. Furthermore, the variation of internal force and horizontal deformation of piles mainly occur in the zone of three times of embedded depth of tunnel along piles. With the increment of the force of shield construction, the horizontal deformation of piles decreases.

Sun X.,Zhejiang University | Xu C.,Hanjia Design Group of China | He Y.,Zhejiang University | Mao J.,Ningbo University of Technology | Zhang H.,Hanjia Design Group of China
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2012

Aggressive environmental conditions and ever-increasing traffic loading contribute to the progressive deterioration, increase the deflection and decrease the capacity of bridge structures over their lifetime. Therefore, maintenance and repair methods should be implied for the requirement of service security. The traffic overload was simulated by static load test, the rebar corrosion was generated by Galvan static method, and the carbon fiber reinforced polymer was used to strengthen these damaged bridge members. Then the BOTDA was adopted to monitor the strain changes in the experiment. The reinforcement effect of CFRP was evaluated by comparing the deflection, crack pattern and strain under various stages. The experimental investigation indicates that damages caused by different factors affect the reinforcement efficiency in different ways. Traffic overload, which causes a comparable large deflection, leads to self-evident interoperability reduction of the strengthened bridge member. The fiber optical sensors embedded in bridge members can monitor the structure performance reliably and stably under traffic overload and erosion environment condition, and it is proved that BOTDA has extensive prospect for monitoring the smart bridge and structures.

Wu Y.-H.,Zhejiang University | Wu Y.-H.,Hanjia Design Group of China | Xie X.-Y.,Zhejiang University | Ye J.,Hanjia Design Group of China | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Based on the design practice of the tall buildings crossing metro tunnels, a three-dimensional finite element of shear wall-piled raft-soil is proposed to investigate the deformation and internal forces of piled raft foundation. The effects of superstructure rigidity, storey-by-storey construction, span length of metro tunnels and crossing methods are analyzed. The results indicate that considering shear wall rigidity can significantly reduce the differential settlement and the bending moment of raft for high-rise buildings. After superstructure rigidity reaches a certain degree, the differential settlement and the bending moment of the raft per unit load increase slowly. This shows the effects of the superstructure rigidity are limited. With the increase of the span length of metro tunnels, the maximum settlement, the differential settlement and the bending moment of the raft increase slightly. The crossing method of raft diagonal which coincides with the center of metro tunnels has the least influence on the internal forces and the bending moment of the raft. The reaction of piles agrees with the measured data.

Shen G.,Zhejiang University | Qian T.,Hanjia Design Group of China | Yang X.,Hanjia Design Group of China | Fang H.,Hanjia Design Group of China | Lou W.,Zhejiang University
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2013

In order to obtain wind loads on a torsion shaped high-rise building with outer pierced ornament structure, wind tunnel testing method was employed. The distribution characteristics of wind pressures and resultant forces on the torsion shaped high-rise building were analyzed. The influence of the ornament structure on wind pressure distribution of the main building was investigated. The wind pressure distribution on the ornament structure itself was also studied. Finally, the resultant forces on the torsion shaped high-rise building with or without the ornament structure were compared. Results show that the torsion shape has significant influences on the local wind pressures and torsional moments of the building and has insignificant influences on the resultant forces in X and Y directions of the building. The ornament structure has insignificant influences on the pressures in the windward and leeward surfaces of the main structure. However, the mean and fluctuating wind loads on the side wind surface of the main structure can be reduced significantly due to the influence of the ornament structure, resulting in a reduction in peak negative pressure which is quite beneficial for wind-resistant design of enclosure structures. The wind pressures on the inner and outer surfaces of the ornament structure are quite close, indicating that the net wind pressures on the ornament structure are very low. Totally speaking, the ornament structure has a insignificant influence on mean wind loads of the main building, but it can reduce the fluctuating wind loads on the main building to some extent. As a result, the wind-resistant design of the main building is beneficial from the existing of the ornament structure.

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