Improvements to the dynamic characteristics and stiffness of composite girder bridges are necessary to expand their applications and capabilities. The natural frequency of a bridge directly reflects the dynamic characteristics of a structure. From the calculation principle for the natural frequency, the natural frequencies of a bridge can be significantly increased if the load increases slightly while the structural stiffness increases significantly. Based on this, a new type of concrete-steel composite truss bridge is proposed. The new bridge has a reasonable new arrangement for the position of the concrete and steel, according to the bending moment law for continuous girders. The mechanical analysis of the new bridge shows that it has the characteristic of adding a small amount of load at a reasonable position, which can significantly improve the stiffness. Therefore, it is possible to achieve the purpose of improving the dynamic characteristics so that they are far better than those of a conventional composite truss bridge. To further study the dynamic characteristics of the new composite truss bridge, the finite element (FE) method was used to analyse the new bridges, and the results are compared with those of conventional composite truss bridges. Furthermore, several parameters that influence the dynamic characteristics of the new composite truss bridge were studied. Finally, the dynamic characteristics of the small-span new bridge were studied by finite element analysis (FEA) and experiment. The results show that the new composite truss bridges with different span arrangements and different second-stage dead loads always have better natural frequencies and stiffness advantages. Therefore, the new composite truss bridge is suitable for girder bridges with strict requirements for their stiffness and dynamic characteristics, especially for super-long span high-speed railway girder bridges.

为了扩大其应用范围和功能，有必要改善复合梁桥的动力特性和刚度。桥梁的固有频率直接反映了结构的动力特性。根据固有频率的计算原理，如果载荷稍微增加而结构刚度显着增加，则桥梁的固有频率可以显着增加。在此基础上，提出了一种新型的钢-钢复合桁架桥。根据连续梁的弯矩定律，新桥对混凝土和钢的位置具有合理的新布置。对新桥的力学分析表明，它具有在合理位置增加少量载荷的特点，可以显着提高刚度。因此，可以达到改善动态特性的目的，以使它们远远优于传统的复合桁架桥。为了进一步研究新型组合桁架桥的动力特性，采用有限元（FE）方法对新型桥梁进行了分析，并将结果与​​常规组合桁架桥进行了比较。此外，研究了影响新型组合桁架桥动力特性的几个参数。最后，通过有限元分析和试验研究了小跨度新桥的动力特性。结果表明，具有不同跨距布置和不同第二阶段静载荷的新型复合桁架桥始终具有更好的固有频率和刚度优势。因此，这种新型组合桁架桥适用于对刚度和动力特性有严格要求的箱梁桥，特别是超大跨度高速铁路箱梁桥。