专业英语翻译2-main

Load test of a plain concrete arch railway bridge of 20-m span

Mohammad.-S.Marefat

a,*

,Esmaeel Ghahremani-Gargary a ,Shervan Ataei

b

a Department of Civil Engineering,Faculty of Engineering,University of Tehran,P.O.Box 11365-4563,Tehran,Iran b

Division of Civil Engineering,Faculty of Engineering,University of Tarbiat Modarres,P.O.Box 11365-4563,Tehran,Iran

Received 1June 2003;received in revised form 13April 2004;accepted 14April 2004

Available online 15June 2004

Abstract

To evaluate the remaining strength of a plain concrete arch bridge,dynamic and static load test was carried out.In the static test,up to 7300kN of weight was applied,and in the dynamic test,a 1200kN locomotive was used.The bridge demonstrated relatively stiffand strong response,despite initiation of enormous cracks,and it yielded under load levels much greater than the service load.The performance could be compared to a multi-layered continuous structure rather than to an arch form.The study showed that the bridge still enjoyed relatively large strength reserve and proper dynamic performance,despite deep and wide cracks,suffering from carbonation,and being more than 60-year old.Ó2004Elsevier Ltd.All rights reserved.

Keywords:Railway bridge;Plain concrete arch;Masonry bridge;Load tests

1.Introduction

Assessment of the remaining load carrying capacity of masonry arch bridges has been studied by many re-searchers in the recent years.Most of the masonry bridges have been built several decades ago,and have been designed for live loads and service conditions that have been changed over time.The residual strength of those structures cannot be predicted,in a reliable man-ner,because of time dependent effects such as fatigue and creep,environmental defects such as cracking and corrosion,participation of non-structural elements such as fill material and pavement layers,variation in restrain conditions,and differences between as-built and design specifications.To overcome such restrictions,field tests provide a dependable solution.

On the basis of construction material,masonry arch bridges may be divided into three groups,namely,brickwork arch,stone arch,and plain concrete arch.Field and laboratory tests on brickwork and stone ar-ches have been reported frequently (e.g.[1–10]).Full-

scale test of plain concrete arches has been published in a few documents [11,12]and is discussed in this paper.In this document,load testing of a plain concrete arch bridge is described.The bridge is more than 60-year old,and suffers from severe cracking and relatively deep carbonation.The number of this type of bridges,in the railway network of Iran,exceeds several thousands.There are concerns about the safety and serviceability of those bridges under increasing axle load and traffic volume.It was decided to perform load test on Bridge Km-23that has been decommissioned in the recent years.

2.Description of the bridge

The bridge is located at kilometer 23of Tehran-Qom Railway and consists of two identical 20-m arches.The structure suffers from extensive cracking,at the crowns of all spans,and environmental damage.The crack width,at the soffit,varies between 10and 30mm and extends throughout the entire section.There are also visible cracks,up to 3mm wide and 100–600mm long,at the springing of all spans.Reinforcement has not been used and all structural parts,including the arch,

*

Corresponding author.Tel.:+9821-611-2292;fax:+9821-646-1024.E-mail address:mmarefat@ut.ac.ir (M.-S.Marefat).

0950-0618/$-see front matter Ó2004Elsevier Ltd.All rights reserved.

doi:10.1016/j.conbuildmat.2004.04.025

Construction and Building Materials 18(2004)

661–667

Construction and Building

MATERIALS

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