Study On Type Selection Of High Pier Bridge In High Altitude Gorge

With the implementation of China's western development strategy,the road construction in Northwest China will usher in unprecedented opportunities for development in the next few years.However,the Northwest has its unique geographical characteristics,such as relief,hypoxia,cold,drought,wind and wind,especially in plateau continental climate as the representative of the Qinghai area,where the temperature,wind,rainfall and less,the sunshine time is long and strong radiation.For the area more than 3000 meters above sea level,the annual temperature lower than 0 DEG C for 6~8 months,in the construction of high pier bridge will face many problems.Therefore,when designing a bridge,the stability of the structure and the mechanical properties after the completion of the bridge must be taken into full consideration.This paper relies on an altitude of 3000 meters in Qinghai Province,Wolong No.4 ditch bridge engineering,the two design schemes proposed,analyzed from the construction feasibility and economy,pointed out to meet the needs of construction by using conventional precast T beam bridge can be better.According to the basis of engineering examples,the structure of different types,different height of the bridge,using the finite element software Midas-Civil stability analysis,pointed out that with the increase of pier height,structure stability decreased gradually;a big difference in the stability coefficient of the same pier pier under various sections,from small to large order of double circular,rectangular solid pier pier and rectangular thin-wall hollow pier.At the same time,the whole process stability of the bridge from the construction to the completion stage is analyzed in detail.It is pointed out that the safety factor of the high pier bridge is lowest when the T beam is erected on both sides.Secondly,in view of the simply supported continuous rigid frame bridge T,the beam will be continuous rigid bridge and continuous girder bridge are compared,the difference between the two types of bridge in space and the overall stress.The results show that the weight load of bridge girder internal force of two trend is basically the same;in the continuous beam structure system,influence of temperature load on the internal force of the structure is very small,can be neglected,but the wind load will cause the girder internal force increases rapidly,for the safety of the structure will produce adverse effects;in high pier continuous rigid frame in the system,low temperature load and wind load effect on the internal force of the structure,the structure of the stress state is more stable.In addition the pier beam consolidation type to high pier stability,to improve the structural stress has obvious effect,is also more prominent advantages of large stiffness,high stability of T beam of continuous rigid frame bridge.Finally,on two different Pier(rectangular solid pier and rectangular hollow pier)with two different superstructure(continuous girder and continuous rigid frame)are combined to analyze their vibration characteristics,pointed out that the natural frequency of a vibration frequency is greater than the first order continuous girder bridge of continuous rigid frame bridge when the pier;rectangular thin-wall hollow pier,bridge structure corresponding to the natural frequency of the structure is greater than the natural frequency of rectangular solid pier.