General Expression of LRC Method in Estimation of Bridge’s Equivalent Static Wind Load

According to the relationship between load and response, the equivalent static wind load(ESWL) of a structure can be estimated by load-response correlation(LRC) method, which can be accurately used to estimate the background ESWL of a structure. The derivation of the classical expression of LRC formula is based on a specific command response at a critical position, and the ESWL distribution has only one form in this case. In this paper, a general expression of LRC formula is derived based on a specific command response at all positions. For the general expression, ESWLs can be expressed by load-response correlation coefficients, response-response correlation coefficients, RMS values of the fluctuating wind loads, and peak factor in the form of matrices. By comparing the expressions of LRC method, it was found that the classical expression was only one form of the general one. The general expression which introduces the response-response correlation coefficients provided more options for structural engineers to estimate ESWLs and offered further insights into the LRC method. Finally, a cable-stayed bridge, a rigid three span continuous girder bridge, and a suspension bridge were used to verify the correctness of the general expression of LRC method.

Trial design of arch bridge of composite box section with steel web-concrete flange

The concrete arch bridge is a natural and appropriate structural solution,aesthetically pleasing and easily integrated into the environment,especially in mountainous and island areas.However,construction difficulty and cost will increase with heavy self-weight when the span enlarges.A potential solution is to use a composite box arch ring with steel web-concrete flange.Taking Wanzhou Yangtze River Bridge(the longest concrete arch bridge in the world with a main span of 420 m)as a prototype,trial designs of a composite box arch with steel webs(including corrugated steel webs and plain steel webs)and concrete flanges were carried out.Comparison of quantities and structural behaviors of the prototype concrete arch with the two trial designed composite arch was presented.It is shown that the selfweight of the composite arch can reduce about 28%and the structures can meet the design requirements,therefore it is possible to use the two composite arches in long span arch bridges.