For conventional bridges on expressways, small and medium-sized span prefabricated beam (plate) structures with spans in the range of 16m-40m are the most representative bridge structures, and they are also the most economical and reasonable compared with other bridge structures. On the basis of satisfying the functional requirements, the bridge structure should be standardized and assembled as much as possible, so as to improve the construction progress and quality of the project and reduce the project cost. The main forms of general bridge superstructure are hollow slab, small box girder, and T beam. For non-special cases, hollow core slabs are generally used for 10-20m spans, small box girders are generally used for 20-30m spans, and T-beams are generally used for 25-40m spans.
It can be seen that there are several structural forms to choose from between 20-30m span, and this range is often the most used span of expressways, so the structure comparison needs to be carried out for different beam types of the same span to obtain the optimal scheme. In the process of comparison and selection, it is necessary to focus on factors such as economy, construction convenience, durability and service level according to the characteristics of the project.
The conventional bridge structure system is divided into simply supported beams and simply supported continuous, which also need to be compared for different construction environments. For example, the simply supported beam system should be selected in the multi-soft foundation area, and the uneven settlement has little influence on the upper forceIn the area of high intensity, it is advisable to choose a simple and continuous system, which has good integrity. Generally, the 10-30m span can be simply supported beam system, and the 20-40m span can be simply supported to continuous system. Different systems have their own different advantages and disadvantages, the simply supported beam system has the advantages of simpler stress, more convenient construction, lower cost, can adapt to larger foundation settlement, etc., but its disadvantage is that the spanning capacity is limited, the driving comfort is slightly poor, the integrity is weak, etc., and the advantages and disadvantages of the simply supported beam continuous system can be interchangeable with the simply supported beam system.