Determining initial pretension values of pre-stressed cables is one of the key problems for a steel mega frame and pre-stressed composite bracing structure.Through the mechanical analysis of the composite bracing unde...Determining initial pretension values of pre-stressed cables is one of the key problems for a steel mega frame and pre-stressed composite bracing structure.Through the mechanical analysis of the composite bracing under vertical loading,the critical factors deciding the initial pretention value were found.According to these factors,a rule for the initial pretension value was put forward.The determination equations were acquired based on the principle of force equilibrium at nodes.The numerical results indicate that the internal force disequilibrium in composite bracings resulted from symmetrical load can be eliminated only in a symmetrical way,so that initial pretention values are decided only by vertical loads.The influencing coefficient leveling method,taking into account interactions between story and story,is accurate and feasible.展开更多
According to the interaction of three shallow tunnels with large section, the analytical solution to rock pressure has been derived and discussed. The load model is given when the bilateral tunnels are excavated. Acco...According to the interaction of three shallow tunnels with large section, the analytical solution to rock pressure has been derived and discussed. The load model is given when the bilateral tunnels are excavated. According to the model, the stresses of three tunnels and single tunnel are calculated and compared to analyze the distribution characteristics, where the stresses are influenced by controlling factors of clear distance, covering depth and inclination angle of ground surface. The results show that, in general, the bias distribution is more serious. Therefore, it is significant to settle down the load model of three shallow tunnels so as to determine the measure of reinforcement and design the structure of support. The model and results can be used as a theoretical basis in designation and further research of the three shallow tunnels.展开更多
基金Project of Ministry of Housing and Urban-Rural Development of China(No.2012-K2-28)
文摘Determining initial pretension values of pre-stressed cables is one of the key problems for a steel mega frame and pre-stressed composite bracing structure.Through the mechanical analysis of the composite bracing under vertical loading,the critical factors deciding the initial pretention value were found.According to these factors,a rule for the initial pretension value was put forward.The determination equations were acquired based on the principle of force equilibrium at nodes.The numerical results indicate that the internal force disequilibrium in composite bracings resulted from symmetrical load can be eliminated only in a symmetrical way,so that initial pretention values are decided only by vertical loads.The influencing coefficient leveling method,taking into account interactions between story and story,is accurate and feasible.
基金Projects(2013CB036004, 2011CB013800) supported by the National Basic Research Program of ChinaProject(51178468, 50908234) supported by the National Natural Science Foundation of ChinaProject(2011G103-B) supported by the Science and Technology Development of Railway in China
文摘According to the interaction of three shallow tunnels with large section, the analytical solution to rock pressure has been derived and discussed. The load model is given when the bilateral tunnels are excavated. According to the model, the stresses of three tunnels and single tunnel are calculated and compared to analyze the distribution characteristics, where the stresses are influenced by controlling factors of clear distance, covering depth and inclination angle of ground surface. The results show that, in general, the bias distribution is more serious. Therefore, it is significant to settle down the load model of three shallow tunnels so as to determine the measure of reinforcement and design the structure of support. The model and results can be used as a theoretical basis in designation and further research of the three shallow tunnels.
