Abstract:

In this paper,a theoretical formula describing the temperature effect on the frequency of simply-supported beam is deduced. Thenby taking a single-pylon cable-stayed bridge with curved composite beam as the object,the temperature response and the effect on the frequency are analyzed,and a finite element method is proposed to quantify the effect of ambient temperature on the frequency of complex structures. The results show that ( 1) ambient temperature influences the modal frequency of the bridge structure mainly in three ways,namely,changing the structural size,producing internal force in the statically indeterminate structure and changing the mechanical properties of the structural material; ( 2) the influence of structure size change on the modal frequency can be neglected; and ( 3) the influence degree of ambient temperature on the modal frequency mainly depends on the structure form,the material,the section size and the internal force state. Moreover,case study results indicate that ( 1) different temperature modes have different influences on the deformation and the internal force of the structure; ( 2) the influence of uniform temperature on the modal frequency of cable-stayed bridge is mainly due to the change
of elastic modulus,while the influence of girder temperature gradient is mainly due to the change of internal force; and ( 3) neither the cable temperature difference nor the pylon temperature gradient has any significant influence on the modal frequency.

Key words: temperature, modal parameter, simply-supported beam, cable-stayed bridge, finite element