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these changes were slight, which led to the conclusion that the
theoretical principles used at the design of the system were sound
and adequate to the reality of the Brisa network and of Portugal.
In complementwith the systemvalidation, the data collected in
the inspection campaign allowed a statistical analysis that revealed
interesting aspects concerning road bridges expansion joints, both
in terms of typology and pathology. These aspects are presented in
detail in each section of the paper. The main conclusions that can
be drawn from the inspection campaign are that:
some types of joints have been systematically replaced (open
joints, nosing joints with poured sealant, buried joints under
continuous surfacing, steel sliding plates) inmany cases in favor
of elastomeric solutions;
made-to-order joints are no longer prescribed and designers
systematically prescribe pre-fabricated solutions from specific
manufacturers; the transition strip and the anchorage cavities need more
maintenance andmore frequent rehabilitation than other parts;
the type and frequency of defects is highly dependent on the
type of joint and its age;
installment errors and lack of maintenance are the most
frequent causes of pathology (in around 66% of the cases),
followed by changes from the predicted service conditions and
fabrication errors;
direct or indirect visual observation is still the best diagnosis
method but acoustic/noise measurements use may be recom-
mended in many cases;
specific types of joints show specific needs in terms of
maintenance / rehabilitation;
the importance of the defects found depend a lot on the type
of joint and of the defect; a bridge stock subjected to frequent
maintenance seldom shows defects that require urgent or very
urgent rehabilitation work.
As a final remark, expansion joints have greatly improved in the
last few years. A great contribution to that effect has been given by
the establishment of companies specialized in this field that have
developed and commercialized new types of joints, based mostly
in multi-material solutions in which elastomeric materials play an
important role. The campaign presented showed that there are no
perfect solutions and therefore a capable maintenance is always
required. It is necessary to keep on investing in the study of new
or improved systems and materials, with special emphasis on the
materials used in sealing anchorages and in transitions strips. In
global terms and in what concerns the joints architecture's R & D,
experience has shown that simpler systems, with fewer moving
parts, are more reliable as they demand less maintenance and
guarantee greater durability.
Acknowledgements
The authors thankfully acknowledge the support of the ICIST
Research Institute from IST, Technical University of Lisbon, FCT
(Foundation for Science and Technology), and Brisa, Highways of
Portugal, S.A.
References
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de pose. Entretien et réparation, Service d'Études Techniques des Routes et
Autoroutes. Ministère de l'Equipement du Logement de l'Aménagement du
Territoire et des Transports Direction des Routes. Bagneux (France). 1987.
[2] Johnson ID, Cuninghame JR. The performance of expansion joints: A survey of
250 joints on highway bridges. In: Proc. Bridge Management 2. 1993. p. 1107.
[3] Marques Lima J, de Brito J. Management system for expansion joints of road
bridges. Struct Infrastruct Eng 2007 [in press].
[4] Marques Lima J. Expansion joints in road bridges development of a
management system. Masters in Construction Dissertation. Lisbon: Instituto