Applied Mechanics and Materials Vols. 405-408

Abstract: By analyzing the characteristics of shock waves in underwater blasting of two bridge piers and monitoring their pressures, this paper found the rule that shock wave pressure varies with different distances from the explosion source. The method of comparison was applied in this study. Based on the characteristic parameters such as pressure amplitude and positive action time, the attenuation formula of shock wave in shallow water was proposed. The results of this paper are of great importance to the engineering design and construction as well as environmental safety assessment.

Abstract: Firstly, we described the basic situation of dendritic structure. Then studied the elastoplastic time-procedure analysis of the dendriform-column, and researched in dynamic performance of structure under seldom occurred earthquake. Finally, we presented the performance difference comparison in the hinged support and fixed support conditions, and the corresponding analysis for folded plate grid frame structure. All these experiences will promote the application of dendriform-column in folded plate grid frame structure on the design and research work.

Abstract: Based on the theory of virtual work and principle of thermal elasticity, exact solutions for in-plane displacements of curved beams with pinned-pinned ends are derived explicitly. In the case of infinite limit of radius, these equations coincide with that of the straight beams. Compared with the results of FEM, the analytical solutions by the proposed formulae are accurate. Basing on the stiffness matrix of statically indeterminate curved beams at three freedom direction, the dynamic characteristics are derived explicitly. The analytic method of dynamic characteristics for curved beam performed in this paper would provide a scientific base for further study and design of the curved bridges.

Abstract: Eight concrete columns with various sizes confined by CFRP and four plain concrete columns as the control specimens were axially loaded to failure in order to investigate size effects in concrete columns confined by CFRP. Experimental results show that CFRP can increase considerably both the capacity and ductility of the concrete specimens. Furthermore, the peak stress of the unconfined concrete decreases with the size of the specimens increasing. Similarly, the peak stress of confined concrete decreases with the size of the specimens increasing when the lateral confining stresses are the same. Hence, the size effects should be considered in the stress-strain model of concrete confined by CFRP.

Abstract: In order to investigate the pressure distribution around the reticulated shell structure with large span, a commercial Computational Fluid Dynamic software Fluent is employed to obtain the wind load and the coefficients of the time averaged pressure distribution around the reticulated shell structure in this paper. The numerical simulations of surface pressure are consistent with the experimental results. The characteristics of the wind pressure distribution are described through the flow analysis around the reticulated shell structure. All these discoveries can be used as a reference for the new version of the wind load criteria.

Abstract: Metal lamp pole is widely used in road lamp. The structure of the metal lamp pole is more and more complex. It needs to open holes on the metal lamp pole. To determine bearing capacity and safety properties of the lamp pole after opening hole, this paper used ABAQUS software to make finite element analysis of the metal lamp pole and accurately got the deformation and stress of metal lamp pole. By means of comparing the stress situation of the metal lamp pole with and without holes, it summaries up the influence rules of holes on the mechanical behavior of metal lamp pole. There is an obvious stress concentration phenomenon around holes and the influence degree of different holes location of stress concentration is also different. Through finite element simulation analysis, it meets the project safety and provides reference value for optimization design of lamp pole.

Abstract: 3-D numerical simulation is carried out for the water flow when the three overflow radial gates use different opening velocities. The space-time change law of hydraulic characteristics is obtained. The water surface profile in the stilling basin fluctuates greatly during the processes; the maximum pressure on the slab of stilling basin increases and moves to downstream with the gates opening; the velocity near the slab of stilling basin corresponding to the left orifice is much larger than that corresponding to the right one. The calculated water surface profile is in good agreement with the results obtained in experiments. The results can provide important basis for operation mode of radial gate.

Abstract: Flat truss is a new form of truss and are widely used in large-span space structure, Suzhou Railway Station roof of the main use of space for large-span steel diamond plate truss structure, the local two-way cross-diamond-shaped truss.Sap2000 v14 large general-purpose finite element analysis software, the modal analysis of the structure, and the modal response spectrum method the structure of X, Y, Z three earthquake, so as to arrive seismic coefficient of internal force distribution law, obtained the natural frequency of the structure, the vibration characteristics of the structure, so that the corresponding structural measures its weak parts of the structure, provides a sufficient basis for the safe use of the design and construction of the structure.

Abstract: Due to the superiority of high corrosion resistance of FRP materials, more and more attentions have been attracted to the retrofitting of corroded reinforced concrete (RC) columns with FRP. This paper thus presents an experimental study on mechanical performances of corroded RC columns strengthened with FRP, focusing on the effects of different corrosion rates of the reinforcements and the retrofitting scheme. The effectiveness of externally bonded FRP to the corroded RC column to increase its load capacity and ductility is tested; the mechanical performances of the strengthened columns are theoretically investigated. The results indicate that the effectiveness of retrofitting the existing corroded RC columns with FRP jackets is much more significant than that of retrofitting the newly built columns with FRP jackets and externally wrapped with FRP jackets is much more effective to improving the structural performances of heavily corroded columns.

Abstract: This paper has investigated the reliability of concrete filled FRP tube columns using the FRP confined concrete theory developed recently by the authors. The reliability index of the column is assessed by Monte Carlo method. The importance of the use of partial safety factors of FRP and concrete in the reliability design of concrete filled FRP tube columns is studied. The results indicate that the reliability index of concrete filled FRP tube columns increases remarkably as the FRP partial safety factor increased. It is concluded that the FRP partial safety factor is independent on the coefficient of variation of FRP strength but is highly sensitive to the coefficient of variation of concrete strength especially in the case of low confinement ratio. Considering the actual situation in engineering applications, to reach a target reliability index of 3.5, a partial safety factor of 1.4 is finally recommend for both FRP and concrete.