The Research On The Design Of Straight Going Fast Assembling Car Overpass

In recent years, with the rapid growth of national economy, population mobility has been accelerated, logistic transportation has developed rapidly, motor vehicles have increased fast, all of which lead to a significant increase of traffic demand and a increasingly heavier burden of urban roads. However, the velocity of construction of road in large and medium-sized cities is slower than the increase of the traffic demand, therefore the trouble of traffic jams, low velocity of vehicle speed and traffic accident is more serious. Meanwhile, currently many transporting construction projects in urban, like light rail, the subway, rebuilding of existing road and so on, are constructed together, which makes traffic problems more obvious. Transportation research shows that, cars occupy a high proportion in cities' congested vehicles. Hence, if cars can be diverted rapidly and effectively, then treating with traffic jams and congestions will definitely obtain significant effectiveness.In dealing with the widespread traffic congestion in the large and medium-sized cities at the traffic system construction period, in this paper, reasons of traffic jams are analysed. Based on current main concepts and special measures of treating traffic jams put forward in home and abroad, according to blocking sources and positions of traffic jams, a concept that setting up a temporary detachable car overpass, which is suitable to traveling straight cars, has been put forward. Several jobs have been done as followed:First, according to traffic jams' blocking positions (crossings and constructed part of roads) and blocking sources (cars), applying targets and plane layouts of car overpass are analysed. Then, structural requirements of overpass is discussed, and based on features of steel-truss structures, overpass's structural type is preliminarily determined.Then, based on structural requirements, steel-truss girder bridge and steel truss cable-stayed bridge are first selected as overpass's alternative plans. Based on preliminarily determining structure's detailed design, materials and designing loads, adopt ANSYS to analyse two plans from strength rationality and construction workability, and then compare them. Based on the analysis and comparing results, steel truss cable-stayed bridge is selected as the final plan. Then strength check, the overall and local stability checking of overpass's main structural elements are further done.Through modal analysis of overpass structure, it shows that, overpass's fundamental frequency is closed to its vehicle loads', which obviously responses to vehicle vibration. Hence, in this paper, overpass's dynamical response to moving loads is analysed, and according to analysis results, several suggestions of overpass's security settings are put forward.Finally, according to this novel treating sets of traffic jams, recommended plans of construction, organization and design are provided. Also, according to possible dangerous factors during overpass's using, safe plan is offered.In this paper, car overpass is introduced from structural design in detail, constructing orgnaization, supporting infrastructure and so on. It is hoped that this novel set can be popularized to all cities in China, or even to other areas besides transportation.