Method for acquiring impact coefficient of simply supported girder bridge

Abstract

The invention discloses a method for acquiring an impact coefficient of a simply supported girder bridge, which comprises the following steps of converting a pavement roughness spectrum of the simply supported girder bridge into a pavement roughness spectrum expression taking time frequency as a variable according to a single free vehicle system with a known speed; calculating the power spectrum density of vibration response of the vehicle system under the action of the pavement roughness spectrum according to the mass, rigidity and damping of the single-free vehicle system, and obtaining the random acting force spectrum of the simply supported girder bridge according to the power spectrum density; constructing a random process according to the random acting force spectrum of the vehicle, and converting the random load of the vehicle system into a series expansion of a time-frequency domain; performing modal decomposition on the motion equation of the simply supported girder bridge, and solving the modal motion equation of the simply supported girder bridge under the action of the moving random load by utilizing a trigonometric function product sum-difference method to obtain a probability statistical characteristic value of the dynamic response of the simply supported girder bridge; and calculating the ratio of the root variance of the vibration response to the maximum static response to obtain the impact coefficient of the simply supported girder bridge.

Description

technical field [0001] The invention belongs to the technical field of simply supported girder bridge structures, and relates to a method for obtaining the impact coefficient of a simply supported girder bridge. Background technique [0002] Traffic load is one of the most important loads on simply supported beam bridge structures. In design, traffic loads are usually first calculated as static loads and their static effects are combined with the effects of other dead loads and live loads. However, the traffic load is a moving load, and because of the vibration of the vehicle caused by the uneven road surface, the traffic load has obvious dynamic effects, which are usually included in the design work through the impact coefficient. The shock coefficient is defined as the ratio of the difference between the maximum dynamic response and the maximum static response under the vehicle load to the maximum static response. The strength of the impact effect is related to many fact...

AI Technical Summary

Problems solved by technology

However, due to the many factors affecting the impact coefficient of bridges, and the results of dynamic load experiments and numerical calculations are highly random, so far people have not obtained a theoretically perfect calculation formula for impact coefficient that can consider the influence of various factors

The impact coefficient formula recommended by my country's current "Bridge Regulations" takes the fundamental frequency of the bridge (first-order vertical bending frequency) as a single variable. This formula is a monotonically increasing function of frequency and cannot reflect the law of vehicle-bridge resonance, nor can it reflect road conditions, etc. factors

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