Abstract
Split-type steel box girders are widely used in long-span bridges because of their good wind-resistance performance. In the design stage, a simple finite element model is usually established based on the beam element for wind-resistance design. However, since the irregular cross-beams and diaphragms in the split steel box girder cannot be virtually established, the stiffness of the girder will be underestimated. To improve the accuracy in simulating stiffness of the split-type triple-box steel box girder (STSBG) with the beam element model (BEM), a correction is made to the initial beam element model (IBEM) based on the result of a more refined finite element model. ANSYS is adopted to make a refined model (RM) of a bridge with STSBG as its girder and to calculate its aerostatic responses and dynamic characteristics in 3 typical construction states and 1 finished state. With the reference value, an objective function of the overall residual sum of squares is constructed for the torsion angle of the girder and the frequency of the bridge. Then, the beam element is used for conventional modelling of the bridge, and artificial bee colony (ABC) algorithm is adopted for the optimization and correction of structure parameters of the BEM of the girder. Finally, static and dynamic characteristics of the IBEM and the corrected beam element model (CBEM) are compared with values of the corresponding RM to evaluate the validity of the correction of the model. The results show that the aerostatic responses and dynamic characteristics of the CBEM are close to calculated values of the RM. In more detail, the relative error between the torsion angle of the girder in the middle span of the BEM and the corresponding reference value in the finished state is decreased from +61.71% to +4.94%, and the relative error of torsional fundamental frequency is decreased from −17.43% to +3.66%. According to the calculated value of the RM, ABC algorithm would satisfactorily improve the accuracy in simulating torsional stiffness of the STSBG with the IBEM. This research is expected to provide reference for beam element modelling, which is conducive to accurately simulating torsional stiffness of the STSBG.
Highlights
It is common that the finite element model of the long-span bridge is built by simulating girder or member based on onedimensional two-node beam elements
Zhang and Ge [5] took Jiangyin Yangtze River Bridge as an Advances in Civil Engineering engineering object to establish a beam element model (BEM) and a shell element model for dynamic analysis, and they found that the antisymmetric torsional frequency of the first order of the girder has a discrepancy of 10.25%, and the antisymmetric transverse bending frequency of the first order has a discrepancy of 17.75%
As per the finite element simulation results of Zhang and Chen, the U-shaped ribs and intermediate diaphragms could not be directly simulated by the initial beam element model (IBEM), because, in that way, it would result in an underestimation of the torsional stiffness of steel box girder, inducing a certain difference between the static and dynamic characteristics of the bridge and the real value of the actual structure
Summary
It is common that the finite element model of the long-span bridge is built by simulating girder or member based on onedimensional two-node beam elements. Previous studies mainly focused on the influence of changes of parameters on the dynamic characteristics of bridges and some methods to improve the torsional stiffness of structures but failed to fundamentally solve the problem of BEM simulation accuracy of such steel box girders. If the multigirder modelling method is employed, the torsional stiffness of each steel box can be calculated by the above analytical formula (or by reading the cross section with the aid of finite element software), but the irregular cross-beams and the diaphragms inside the box cannot be virtually simulated, because, in that way, it will result in the distortion of the overall torsional stiffness simulation of the girder to a certain extent. It is of practical significance to use the calculation results of the more refined shell element model as a reference value at the design stage to correct the parameters of the IBEM to achieve equivalence between the two in terms of static and dynamic performance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
