Abstract: The seismic fragility of R/C frames was redefined as the conditional failure probability of the structure with regard to the ground motion index and structural service age in this paper. An analytical method was proposed to disclose the seismic fragility variation of reinforced concrete frames with respect to the service age. Considering the variation of nonlinear mechanical characteristics of un-carbonated concrete within the service life, the seismic fragility variation of frames was analyzed using the inter-story drift ratio in the weak storey. For the defined damage levels of frames, each seismic fragility curve variation reflects the failure probability change tendency within the service life. A R/C frame was modeled to illustrate the variation of the seismic fragility within the service life.
Abstract: With development of underground space, the shield tunneling method have been widely adopted due to its unique advantages. However, there is still many technical and theoretical problems need to be improved in the construction. Based on the project of metro line 1 in Hangzhou city, typical problems of shield tunnel construction in sandy soil are analyzed. The problems of ventilation system, cooling water circulation system, foaming system and conveyor belt system are represented in detail. Controlling of proper propelling force is optimized by parameter sensibility analysis. Aiming at these problems, improvement measures are proposed and successfully used in the project. The improvements can be taken for reference in similar projects.
Abstract: Through the trisection loading test on two hundred-year-old wood beams reinforced with single-layer and double-layer CFRP sheets along the bottoms, the reinforcement effect of CFRP on the bending behavior of the wood beams with corrosion damage has been analysed, and the influence of the number of the CFRP layers on the reinforcement has been researched, thus obtaining the bending behavior of the wood beams reinforced with CFRP and the influence of the defect of the wood beams with the reinforcement.
Abstract: In this paper a super high-rise frame-core wall as an example, It was analyzed the frame-core wall structure system under action of earthquake force features, set reasonable seismic performance objectives, analysis the structure reasonable failure mode, made it have enough bearing capacity and ductility for a reasonable design of frame and coupling wall-beam, could make the frame-core wall structure with multiple seismic fortification lines, improve the seismic performance of the frame-core wall structure. Finally, the action of earthquake deformation and seismic shear force distribution was analyzed through the elastic dynamic time-history analysis. After a reasonable optimization analysis showed: Frame-core wall structure could have three seismic fortification lines: coupling beams, core wall, frame structure, and had enough energy dissipation ability at the same time, could form the rational failure mode, improved the seismic performance of the structure.
Abstract: For the engineering background of subway tunnel with initial defects caused by the construction of new down-through tunnels, the aseismatic performance of the existed tunnel is studied so as to reveal the mechanism of seismic dynamic response by using finite difference method. Numerical simulation shows that the tunnel is deforming in its entirety since such physical variables as velocity, displacement and stress in its all key weak points have same dynamic tendency under influence of approaching construction of tunnels, and these variables are much larger than those without any influence. After down-through construction, much influences of aseismatic performance are mainly taking place at both the side wall and the upper arch, and the shearing damage are mainly doing in surrounding soil mass. Due to widely shearing damage after down-through construction, it is suggested that grouting reinforcing should be applied so as to make them much stiffness as a whole.
Abstract: With the extensive use of concrete materials, concrete corrosion as an important hazardous factor of engineering safety and its impact on the engineering safety is receiving attention gradually. In order to study its impact on the safety of mining engineering, this paper summarized the corrosion factor of concrete shaft lining of mine and its research progress, and combined with the actual progress of the concrete corrosion. The author came to the conclusion that we should pay attention to the study of the corrosion of concrete shaft lining of mine, at the same time, analyzed the feasibility of the study. The authors believe that, at the present stage, studies of concrete corrosion are more comprehensive and thorough, and coupled with the comprehensive understanding of the underground environment. It is perfectly placed to study the problems of the corrosion of concrete shaft lining of mine deep and systematically.
Abstract: The special-shaped concrete-filled steel tubular column (SCFST column) is recognized to have high bearing capacity and good fire resistance. This paper introduced a nonlinear FEA approach to analysis the temperature field of SCFST under standard ISO-834 fire condition. Finite element model was built with nonlinear material properties elements in ANSYS; thermal boundary conditions were applied to the model with convection and radiation combined to simulate the fire condition, and several conclusion were obtained from the nonlinear FEA results.
Abstract: This paper describes the successful experience of the directional control blasting of 210m-high reinforced concrete chimney of Nanchang Power Plant in Jiangxi Province called as “First height in Asia”. It emphatically describes the pretreatment measures, blasting cut shape and size, blasting parameters, electronic digital detonator detonating network and blasting safety technology. And the blasting vibration was tested and analyzed, and this paper presents the method for opening the arch overlarge oriented window and comprehensive protection method for anti-flyrock splash, vibration reduction and dustfall. Especially, the electronic digital detonator was first applied in the blasting demolition of 210m-high structures, it improves the delay precision and also has a good anti-stray current effect to ensure that the blasting can be safely implemented in the power plant, and it has a good application prospect in the future large-scale and high level complex engineering blasting.
Abstract: Using the finite element software ANSYS to analyze the CFRP strengthened concrete columns.The concrete columns are in the axial force existence situation, many columns should be reinforced by longitudinal and circumferential CFRP because of insufficient capacity. Subject to loading,11 root columns were designed, aiming to the layer number of CFRP, the location and orientation of CFRP, the eccentric distant of specimens.One of them is a non-reinforcement column.Under compression, bending, shearing and monotonic torsion, the nonlinear finite element model was established to test stressed steel bar in column test specimens, including longitudinal tensile reinforcement, longitudinal compression reinforcement and stirrup, as well as CFRP has been analyzed, including stress changing of longitudinal CFRP and transverse CFRP. The torque-strain curves for relationship were discussed among longitudinal reinforcement, stirrup and CFRP.
Abstract: This paper presents a method to calculate the main frame damage of fatigue directly by the equivalent fatigue load of the wind turbine. This method can take advantage of the equivalent fatigue load to check the damage of the main frame fast. This paper also analyses the weight of each components of the fatigue load, which is convenient for the optimization design of the structure for main frame. Comparing this method with traditional fatigue calculation method, we can find this method is reasonable and veracious. Using this method can greatly improve the efficiency of the damage estimate for the main frame. It can be analogized to other mechanical components, and this method is very valuable in practical engineering applications.