Expansion joints are current equipment applied to almost every type of bridge with relatively high maintenance costs. Furthermore, their service life is generally short (often below 10 years) and lower than the bridge expected service life (over 50 years). In this paper, the results of an inspection campaign of 150 expansion joints in road bridges, the first comprehensive survey of the kind, are presented. They allow knowing and characterizing more properly the expansion joints installed in Portuguese roads and highways, namely in terms of their typology, pathology and rehabilitation. It was concluded that:(a) some types of joints have been systematically replaced (open joints, nosing jointswith poured sealant,buried joints under continuous surfacing, steel sliding plates); (b) made-to-order joints are no longer prescribed; (c) the transition strip and the anchorage cavities needmoremaintenance andmore frequent rehabilitation than other parts; (d) installment errors and lack of maintenance are the most frequent causes of pathology; (e) direct or indirect visual observation is still the best diagnosis method; and (f) the importance of the defects found depends a lot on the type of joint and of the defect.23446
' 2009 Elsevier Ltd. All rights reserved. 1. Introduction
As stated by Leonhardt, expansion joints are ``the weak point
of bridges''. Their service life is frequently much lower than
expected and that is fully proved by the fact that most joints
undergo interventions well inside the warranty provided by the
manufacturers. This involves various types of costs.
In terms of direct costs, SETRA, the Technical Studies Depart-
ment of French Highways, in a studymade a few years ago [1] esti-
mated the cost ofmaintaining expansion joints as between 7% and
8% of the global maintenance costs of bridges. At Brisa, the main
highways concessionary in Portugal, this value has already reached
a peak of 25% very recently.
Furthermore, because lanes are cut to complete the interven-
tions, inconvenience results to the normal flow of traffic penaliz-
ing the users and the reputation of the entities responsible for the
use of the roadways. Finally, malfunctioning of a joint has other
consequences such as corrosion of steel reinforcement in adjoin-
ing concrete elements [2], an increase in discomfort, damage to the
vehicles and risk of accidents that is not to be dismissed.
On the other hand, existing data on this type of equipment
is still minimal and insufficiently pulged. EOTA (the European
Organization for Technical Approvals) presently has a Working
Group active in the preparation of a normative document on road bridges' expansion joints whose publication has been successively
delayed.
Therefore, everyone involved in the prescription, assemblage
and maintenance of expansion joints experiences certain difficul-
ties in dealing with this theme since, in general terms, their inter-
vention is based on documents from manufacturers that are not
completely unbiased. The problemis further increased by the tech-
nological evolution of the materials and manufacturing processes
that are translated into a wider variety of supply.
It is within this context that a management system specifically
for expansion joints was developed, within the Masters course
of the first author, based on various classifying lists and in
corresponding correlation matrices [3]. Its final objective is the
minimization of running costs through an adequate maintenance
strategy. In this paper, the results of an inspection campaign
performed for the validation of this system are presented.
2. Inspection plan 毕业论文
The inspection campaign comprised the study of 150 expansion
joints in 71 bridges within the highways concession network of
Brisa, Highways of Portugal (Fig. 1). In order to obtain a sample 公路桥梁伸缩缝检查英文文献和中文翻译:http://www.youerw.com/fanyi/lunwen_16504.html