Longitudinal forces of continuously welded track on high-speed railway cable-stayed bridge considering impact of adjacent bridges

A proven beam-track contact model was used to analyze the track-structure interaction of CWR (continuously welded track) on bridge. Considering the impact of adjacent bridges, the tower-cable-track-beam-pier-pile finite element model of the cable-stayed bridge was established. Taking a bridge group including 40-32m simply-supported beam and (32+80+112)m single-tower cable-stayed bridge and 17-32m simply-supported beam on the Kunming-Shanghai high-speed railway as an example, the characteristics of CWR longitudinal force on the cable-stayed bridge were studied. It is shown that adjacent bridges must be considered in the calculation of the track expansion force and bending force on cable-stayed bridge. When the span amount of adjacent bridges is too numerous, it can be simplified as six spans; the fixed bearing of adjacent simply-supported beams should be placed on the side near the cable-stayed bridge; the track expansion device should be set at the bridge tower to reduce the track force near the bridge abutment.

Analytical solution to mapping rail deformation under bridge transverse deformation using energy variational principle

The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.

Structural Condition and Deficiencies of Present Constructed Bridges over Zahirshahi Canal and Proposal of New Design Using AASHTO Codes

This paper addresses a comprehensive design of RCC T-beam Bridge based on AASHTO design standards. The bridge is designed and proposed to be constructed over an irrigation canal (Zahirshahi canal) of Kandahar province, Afghanistan that has more than 30 bridges over it. Yet they are not enough, and the demand for construction of new bridges is gradually arising because of the vast urbanization in the surrounding of the canal. Most of the bridges on this canal are Reinforced Concrete Slab (RCS) bridges;?these type bridges are limited by capacity and are generally found only in smaller spans. Since they can only span short distances and are often constructed as multiple-span?bridges with vertical supports between the abutments to allow a longer length.?All constructed slab bridges over Zahirshahi canal are four-span bridges. Constructing multi-span bridges on the canal decreases waterway due to the existence of many piers and footings that could increase the water level during the peak flow, even, sometimes can cause over flow. Taking into consideration these deficiencies of the present (RCS) bridges, two-span RCC T-beam Bridge is one of the best alternatives to be constructed over the canal. In addition, canal cross-sectional dimensions are almost constant along its length, though the construction of two-span RCC T-beam bridge is applicable at any point of the canal. The design is selected based on exclusive survey of the area during all seasons including the peak flowing of the canal.

Effectiveness of external prestressing in enhancing the non-ductile hanger failure mechanism in reinforced concrete inverted T-beams

Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast stringers.Inverted T-beams,contrary to practice with conventional beams,are loaded on the flanges upper surface.This loading configuration causes hanger failure due to the generation of vertical tensile stresses near the bottom of the web.The key purpose of this study is to investigate the efficiency of vertical external prestressing stainless-steel bars in mitigating non-ductile hanger failure in reinforced concrete inverted T-beams.An experimental study on six inverted-T beams,including two un-strengthened specimens,was carried out.The study showed that the value of the prestressing level had a considerable impact on the performance of hanger mechanism in relation to crack pattern,ultimate loads,cracking behavior,load-deflection,strains,and ductility.The experimental results indicated that the suggested method for strengthening inverted T-beams had efficacy in reducing the seriousness of the non-ductile hanger failure and resulted in a strength increase of up to 53% when compared to that of the un-strengthened specimen.Additionally,two analytical models for estimating the hanger capacity and the average crack width of the strengthened RC inverted T-beams were proposed.The models that were proposed exhibited a high degree of agreement with the experimental results.