限制位移桥墩的连续刚构桥抗震性能研究

沿着摇摆桥墩的概念提出一种限制位移桥墩连续刚构桥体系。该体系通过对连续刚构桥墩底和承台之间采取一定措施,使桥梁在地震发生时能够在限制的位移量内活动,减小输入到桥梁结构中的能量,达到减震的目的。通过对一座铁路连续刚构桥的分析,发现这种限制位移桥墩连续刚构桥体系能大幅减小桥墩的延性和强度地震需求,减震效果明显,在选择合适的限制位移量的情况下,可保证桥墩在高烈度罕遇地震作用下几乎保持弹性工作状态,震后经简单处理即可保证使用功能,为震后救援工作带来极大便利,也大大减少了修复成本。

Seismic Performance of a Continuous Rigid Frame Bridgewith Displacement-restricted Piers

Since the beginning of the 1990s, performance-based seismic design theory has entered the mainstream of structural seismic research.The purpose of performance-based seismic design theory is to determine the seismic performance objectives of a building based on its use, importance, and level of seismic fortification.Buildings designed in accordance with those objectives will safely withstand earthquakes that may occur in the future.On the bridge, plastic hinges placed on the piers were used to consume earthquake energy.Design for ductility can avoid collapse of the bridge.However, permanent deformation of the plastic hinges could cause serious damage to the pier.It is difficult to immediately repair bridges following earthquakes.Many transportation functions are significantly slowed or lost.In order to ensure that the transportation capacity of bridges is recovered quickly after a strong earthquake, many structural systems have been proposed, including rocking bridge piers and self-centering bridge piers.The continuous rigid frame bridge system with displacement-restricted piers was consistent with the concept of rocking piers.This structure can realize three important functions:(1) limit the maximum displacement of pier, (2) prevent the bridge from overturning, and (3)adjust the coefficient of friction at the pier bottom.By adhering to these objectives between the pier bottom and the pier cap, the displacement-restricted system allowed the bridge to move with under the action of the earthquake.In so doing, this method can reduce the input of energy to the bridge structure and achieve the purpose of earthquake mitigation.This study concluded that the continuous rigid frame bridge system with displacement-restricted piers could reduce ductility and strength demands on the bridge piers.This paper compared the displacement limits of 2 cm, 5 cm, 8 cm and traditional piers.The results showed that the displacement of the pier top, the bending moment at the pier bottom, and the bending moment of the pier at the bridge beam with the displacement-restricted 2 cm, 5 cm, 8 cm piers were much less than the piers of a traditional continuous rigid frame bridge.The results also show that the amount of displacement restrictions is important.Choosing the appropriate displacement restriction can ensure that the elastic working state of the bridge will be maintained under severe earthquake conditions.This can improve the effectiveness of earthquake relief work and greatly reduce the cost of repairs.