Algorithm to Estimate the Capacity Reserve of Existing Masonry Arch Railway Bridges

Most railway masonry arch bridges were designed according to codes that predate the 1950s; therefore, assessing their load-carrying capacity to comply with current codes is of the utmost importance. Nonetheless, acquiring the necessary information to conduct in-depth analyses is expensive and time consuming. In this article, we propose an expeditious procedure to conservatively assess the Load Rating Factor of masonry arch railway bridges based on a minimal set of information: the span, rise-to-span ratio, and design code. This method consists in applying the Static Theorem to determine the most conservative arch geometry compatible with the original design code; assuming this conservative geometrical configuration, the load rating factor, with respect to a different design load, is estimated. Using this algorithm, a parametric analysis was carried out to evaluate the Load Rating Factor of old arch bridges in respect of the modern freight load of the Trans-European Conventional Rail System, for different spans, rise-to-span ratios, and original design codes. The results are reported in easy-to-use charts, and summarized in simple, practical rules, which can help railway operators to rank their bridges based on capacity deficit.

Local stability of concrete arch bridge based on Ritz method

In order to minimize the self-weight and prevent local buckling failure of thin-walled box concrete arch bridges at the same time, the limit values of width-thickness ratios are deduced based on Ritz method and equivalent strut theory of arch bridge. A new method of determining sectional forms based on the limit values of width-thickness ratios is put forward. Based on Mupeng bridge, the theoretical results are verified by finite element software ANSYS. Results show that the limits of width-thickness ratios are related to concrete grade, equivalent calculation length and radius of gyration, the allowable minimum thickness of Mupeng bridge is 15 cm to avoid local buckling. The limit values of width-thickness ratios deduced in this paper are reasonable and this new method of determining sectional forms is simple and rational to apply in engineering. A scientific engineering calculation method on arch ring design is put forward and it can provide a theoretical basis for the design of thin-walled box concrete arch bridges constructed by cantilever pouring.

Application of knockdown technology for wooden bow arch bridges

The use of wood as a construction material for simple bridges has begun to be abandoned and switch to concrete or steel bridges with considerations of durability and structural strength. However, from an ecological perspective, wood is still the most renewable material by nature itself. Returning to ecologic natural materials is an issue of the United Nation that needs to be supported by educational institutions. This community service begins with determining the span and height of the bridge, followed by planning and calculating the strength of the material. The parts of the bridge are manufactured in the workshop of the Civil Engineering Department, Samarinda State Polytechnic. The assembly and erection processes are carried out in the field. The uniqueness of this program is in the application of the wooden arc bridge model with a raft unloading system by presenting an attractive aesthetic, so that it is hoped that it can again become an option in determining the type of bridge for users.