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Abstract The Fenshui River Bridge is a steel–concrete composite girder bridge with a main span of 90 m. Due to the topographical constraints, the steel box girder was constructed without the use of auxiliary piers, employing incremental launching techniques. This article focuses on the construction technology used for the steel box girder of the Fenshui River Bridge. Firstly, using the influence matrix method, the cable force is determined based on the maximum cantilever state of the structure, with the vertical deformation of the front end of the guide beam and the horizontal deformation of the top of the tower as the control objectives. The unstressed cable length is then calculated based on the mechanical relationship between cable deformation and cable force. A calculation method for adaptive cable force is proposed, which is based on the variation of the stress-free cable length within the adaptive structural system. Next, the finite element analysis method was employed to determine the optimal layout position for the tower. The results indicate that during the incremental launching construction of the steel box girder, the calculated cable forces using the method proposed in this paper are in close agreement with the measured cable forces. At the maximum cantilever state of the structure, the calculated and measured values of the cable force resulted in a percentage difference of 3.96%. The calculated values of deformation and stress in key sections showed a percentage difference of 6.4% for deformation and 6.6% for stress. To maximize the effectiveness of the tower and cable, the tower should be positioned above the bridge pier when the guide beam crosses the maximum span. The findings of this paper can serve as a reference for the construction of similar types of bridges.

Abstract It is difficult to calculate the buckle cable force for the cantilever casting concrete arch bridge. Relying on the 180 m-span Jiming Sansheng Bridge, this paper put forward one method to calculate the initial buckle cable force based on the stress balance method. Firstly, the stress balance equation considering only tensile stress was derived for the first time, and the feasible region of the initial cable force was calculated by the allowable tensile stress of the arch rib, which improved the original stress balance method. Then, using the influence matrix, the initial buckle cable force was optimized by reducing the allowable tensile stress of concrete in stages, and finally the optimal initial cable force was obtained. The practical engineering results show that it is feasible to calculate the initial buckle force. The maximum tensile stress of concrete arch during the cantilever casting process is 1.52 MPa, meeting the specification requirements. The deviation between the calculated and measured stress is less than 12%. The calculated cable force agrees with the measured cable force, and the deviation is less than 2%. The initial cable force is only tensioned once, improving work efficiency. The method and experience of this paper can provide a reference for the arch bridge constructed by cantilever casting.

In view of the limitations of the current code based on the equivalent beam-column method with the “rod mode” instead of the “arch mode” for the calculation of concrete-filled steel tube arch bridges, this paper takes the real bearing mechanism of the arch as the starting point and analyzes the different bearing mechanisms of the arch and eccentric pressurized column. The concrete-filled steel tube arch model test was carried out to analyze the deformation state and damage mode, and the geometric non-linear bending moment of the measured arch was compared with the bending moment value calculated by the eccentricity increase coefficient of the “rod mode.” The results showed that the transfer of internal force is from the axial force to the arch axis, causing the vertical reaction force and horizontal thrust. However, the eccentric compression column only produced the vertical force at the bottom and combines with the lateral deformation indirectly generated by the eccentric distance. In addition, the deformation stage of the arch is basically the same as that of the eccentric compression column. The final failure mode of the arch is 4-hinge damage, and the final failure mode of the eccentric compression column is single-hinge damage. The preliminary geometric non-linear bending moment value obtained by the two modes accords well. Therefore, the main factors for the difference in the bearing mechanism between the two modes are different force structures, force transmission routes, and sources of deformation. Due to the difference in the bearing mechanism, the final failure mode is different, and the deformation ability of the arch is weakened by using the “rod mode” instead of the “arch mode.” The geometric non-linear bending moment of the control section calculated by the eccentricity increase coefficient is conservative, but the influence of the geometric non-linearity of other sections is not considered enough.

To investigate the reasonable range of the inclination angle of arch ribs, a spatial finite element method was employed based on a concrete-filled steel tube (CFST) basket-handle through an arch bridge with a span of 360 m. A spatial finite element model was established using Midas/Civil software, which was verified with actual bridge data. The effects of different arch rib inclination angles were investigated under static loads. The structural natural frequencies, linear elastic stability coefficients, internal forces, and displacements were comprehensively considered to determine the reasonable range of the inclination angle. The results show that when the inclination angle ranges between 8° and 10°, the first, third, and sixth natural frequencies of the structure are increased. It effectively improves the lateral and torsional stiffness of the arch ribs while ensuring optimal out-of-plane stability of the arch ribs. Compared with the parallel arch, the stability is improved by 20.2%. The effects of angle variation on displacement and internal force of the arch ribs were not significant. Considering all indicators, the optimal range of the inclination angle for the arch ribs of 300-m-level highway CFST arch bridges is suggested to be 8~10°.

To study the bearing capacity of a corroded reinforced concrete (RC) arch and analyze the deterioration mechanism of an in-service RC arch bridge, a deterioration simulation under the coupling effect of the environment and load was performed by employing non-immersion energization, and considering the dead load on the arch, single point loading tests of the arch models were carried out; the crack development, structural deformation, and ultimate bearing capacity of a corroded RC arch under service stress were studied; the failure mode of the corroded arch was explored; and a bearing capacity prediction model considering dual deterioration effects of reinforcement corrosion deterioration and arch axis deterioration was established. Results indicated that the spacing of cracks caused by a load on the non-corroded arch was more uniform, and the number and distribution range of load-induced cracks in the corroded arch was smaller, while the maximum crack width was larger. Corrosion significantly reduced the strength of the arch rib; for the deteriorated arch with a corrosion rate of 7.62%, the cracking load and the bearing capacity decreased by 28.57 and 9.84%, respectively. Corrosion weakened structural stiffness, while it does not convert the failure mode of the arch. Only considering section resistance degradation may underestimate the damaging effects of corrosion on the arch structure.

Yelang Lake Bridge is the largest cantilevered single-chamber reinforced concrete arch bridge in China, with a net span of 210 m. In this article, an equation for positioning the height of the formwork before pouring of the arch ring segment was derived, which was suitable for the construction control of the long-span reinforced concrete arch bridge such as the Yelang Lake Bridge. The arch ring segment elevation calculation equation was derived under the two typical working conditions that the concrete pouring of the arch ring segment is completed and the buckle cable and anchor cable tensioning are completed. In addition, two typical working conditions of arch ring segment concrete pouring and cable tensioning were evaluated. Then, a new type of cradle and loading test of the cradle, which meet the requirements of the long segment pouring of the arch ring, were introduced. Finally, the measurement deviation during the construction of the arch segment was analyzed. The linear control results of the arch ring showed that the arch ring segment elevation calculation formula could effectively ensure the accuracy of the arch ring segment construction process under the two typical conditions of completion of concrete pouring of the arch ring segment and completion of the buckle and anchor cable tensioning. The maximum deviation is only 3.1 mm. The line shape after the completion of the arch ring construction was in good agreement with the target line shape, and the deviation between the measured value and the target value was only 2.5 cm, which met the engineering requirements.