# Collapse Analysis of a Two-Span Reinforced Concrete Bridge Model
## 1 Introduction  
Although the continuous girder bridge is the main type of highway bridge, its structural form is simpler than that of long-span bridges. Therefore, few researchers pay attention to it. It has been found that the continuous girder bridge is vulnerable to seismic waves, and many collapse events occur [1, 2, 3]. In order to improve the collapse resistance of this type of bridge, studying the collapse mechanism and the influencing factors of collapse is key.  
In view of the seismic problem of girder bridges, scholars were concerned about different isolation systems and their effects [4]. [PERSON] et al. [5] and [PERSON] et al. [6] studied the collision problem under earthquakes using a shape memory alloy pseudo-rubber shock-induced device and pipe dampers, respectively. The control effect of those devices on superstructure collision was remarkable, but the control effect on structural collapse under large earthquakes was not present.  
In terms of collapse analysis, many researchers conducted research based on typical collapse events to explain the reasons for collapse, such as material corrosion [7, 8, 9, 10, 11, 12], improper construction [13], heavy vehicle partial load [14, 15], vehicle impact [16, 17, 18], site displacement [19, 20], tsunami damage [21], and excessive structural response [22, 23]. A small number of these events was caused by earthquakes. [PERSON] et al. analyzed the collapse of Showa Bridge during the 1964 Niigata earthquake, and the increase ofthe natural vibration period caused by the liquefied ground was the main reason for resonance with ground motion [24]. [PERSON] et al. elucidated the damage mechanism of Tawarayama Bridge, which incurred severe damage by the 2016 Kumamoto Earthquake, and pointed out that the buckling design of the lower lateral members was important [25]. [PERSON] et al. developed the simplified rigid surface coupling method to analyze the collapse of Gaoyuan Bridge in the Wenchuan earthquake, and found the oversize longitudinal displacement caused the girder falling [26]. These scholars have revealed the collapse mechanism of specific girder bridges, but their conclusions cannot be extended to other bridges. If the structural design parameters change, the failure mode may change. When the reinforced concrete continuous beam bridge was discussed, most scholars conducted in-depth research on the damage and failure of the pier column [27]. The collapse mode of the whole bridge system was less explored.  
Considering that there is little research on collapse mode of continuous girder bridges, the collapse mechanism and the influencing factors of the collapse was our main study. The research team for this paper carried out an experimental study and collapse analysis of a two-span continuous bridge under a strong earthquake. The bridge model in the shaking table test was a single structure with a specific span and pier height. The relationship between the collapse mode and the structural design parameters or the seismic input characteristics was not clear. Therefore, this paper presents further research on the above problems and tries to reveal the critical factors leading to the collapse of a two-span continuous girder bridge. Finally, the design suggestions for the bridge are put forward, providing a reference for the seismic design of bridges that will be built and the seismic reinforcement of existing bridges.