Analysis and Study on Bending Vibration Frequency of New Corrugated Steel Web Composite Box Girder

In order to accurately analyze the bending vibration frequency of the new composite box girder, the effects of web folding effect, shear lag, and shear deformation are comprehensively considered in this paper, and the elastic control differential equation and natural boundary conditions of the composite box girder are established by using the Hamilton principle. A one-span composite box girder with corrugated steel webs is used as a numerical example. The effects of height span ratio, width span ratio, web thickness, cantilever plate length, and fold effect on the vertical vibration frequency of the new composite box girder are analyzed. The results show that the analytical solution is in good agreement with the finite element solution. When considering the shear lag and fold effect, the vibration frequency of composite box girder decreases. With the increase in order, the influence of shear lag and fold effect on its frequency becomes stronger. The changes of height span ratio and web thickness of composite box girder have a great influence on its folding effect, while the changes of width span ratio and cantilever plate length have little influence on it. The conclusion can provide a reference for the design of medium section new composite bridge in practical engineering.

Fuzzy comprehensive evaluation method for integral stability of box girder with corrugated steel webs

The traditional stability evaluation method of corrugated steel web box girder ignores the calculation of evaluation index weight, which leads to large deviation of evaluation results. Therefore, a new fuzzy comprehensive evaluation method for the overall stability of box girder with corrugated steel webs is proposed. According to the structural characteristics of corrugated steel web box girder, the stability coefficient of corrugated steel web box girder is calculated, and the stability calculation index of corrugated steel web box girder is obtained. In this paper, the constraint equation of bridge instability process is introduced, and Midas civil software is used to simulate the instability of box girder with corrugated steel webs during bridge construction. Based on this, the instability of the bridge is analyzed, the index weight of the anti-instability ability of the box girder with corrugated steel webs under different loads is calculated, and the overall stability of the box girder with corrugated steel webs is evaluated by fuzzy comprehensive evaluation. The test results show that this method can accurately evaluate the overall stability of box girder with corrugated steel webs, and the calculation accuracy is increased by 32.7% and the calculation speed is increased by about 1.62 seconds. It has high credibility and authenticity.

Effect of encased concrete on section temperature gradient of corrugated steel web box girder

Thirty-two temperature sensors, a solar radiation sensor, wind speed, and direction sensor were installed on the bridge for the field monitoring of structural temperature, solar radiation, and wind. The frequency was set at 60 min for 211 days. Empirical equations were used to predict the maximum vertical and lateral temperature gradients, and the daily maximum and minimum mean temperatures of the corrugated steel web box girder. The results showed that the temperature gradient of the corrugated steel web box girder was closely related to the temperature gradient of air. The vertical maximum temperature gradient occurred at 4 pm. The height of the box girder had a significant effect on the accuracy of the predicted vertical maximum temperature gradient. Compared with the section without encased concrete, the maximum temperature gradient of the encased concrete section was reduced by 10.48%. Encased concrete showed minimal effect on both the vertical and lateral temperature gradient of the top plate part, however, the effect on the vertical temperature gradient of the haunch reduced by 17.19%. The maximum temperature gradient of corrugated steel with a composite encased concrete section was 4.12°C, which was less than that of the section without encased concrete at 5.06°C. The encased concrete had a significant effect on the maximum temperature gradient of corrugated steel web with a 26.99% deviation.

Experimental and finite element study of optimal designed steel corrugated web beams

The structural performance of standard steel sections in long-span constructions gradually deteriorates due to wider and slighter webs that tend to buckle. This is the characteristic problem of plane webs. Corrugated steel web plates allow a considerable reduction of weight and increasing the web capacity of the beam. The experimental test results of optimal designed corrugated web beams, fortifying thin-walled steel girders without stiffeners, under load conditions, have been compared with the 3-D plane strains finite elements ( FE) model in this paper. The span of fabricated corrugated web beams ( CWB) is chosen as 5 m. These optimally designed CWB are exposed to a single concentrated loading, two-point loading, and partially distributed loading, respectively. The design methods for CWB are firefly optimization and hunting search algorithms. The implementation of design constraints is based on the EUROCODE, DIN, and DAST-Ri. 015 code provisions. The load-displacement curves, the residual load capacity, and the failure form of eighteen tested corrugated web beams are inquired in depth along the experimental process. The structural analysis software ANSYS is used for the simulation of the experimental study, the verification of all test results, and the investigation of the behavior of failure forms.