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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
Comparison and calibration of numerical models from monitoring data of a reinforced concrete highway bridge
1.
Introduction
The last decades presented a significant growth of bridges and
viaducts in Brazil which suffered from early deterioration caused by
lack of maintenance programmes. Although Brazil presents regu-
lations that provide procedures for bridges assessment, in most
cases those procedures are only taken when the deterioration of
the structure reaches a critical state where users are under risk
(Oliveira [1]), (Lencioni [2]).
A case study by SINAENCO (National Union of Architecture and
Consulting Engineering), titled “Infrastructure of the City: Expiration
Date”, shows the need for a permanent policy of maintenance and
management of structures. Regarding the city of São Paulo, the
study shows that more than 240 bridges and viaducts are in a state
of deterioration, offering risk to users. One of the main reasons for
the deterioration is given to the low investment, which corresponds
to less than 0.38% of the construction budget (SINAENCO [3]).
On the other hand, some initiatives concerning the behaviour of
the structure can be found. The cable-stayed bridge over Pinheiros
river, where runs a station on Line 5 of the underground system in
the city, was monitored for temperature, strain and acceleration
during its constructive phase until operation. Also, due to the com-
plexity of the structural solution adopted by the construction meth-
od for Bernard Goldfarb bridge located in Pinheiros, São Paulo, it
was monitored for deformation not only during construction but in
subsequent years. The newly-built cable-stayed bridge João Alves,
located in Aracaju-SE, is an example of a particular bridge that is
being continuously monitored (ASSIS [4]).
Thus, this paper aims to propose a monitoring plan for a curved re-
inforced concrete road bridge already in service. A bridge located on
the border between the states of São Paulo and Minas Gerais was
chosen as a case study to implement the proposed plan. To evaluate
the structural behaviour of the bridge, a hierarchy of six numerical
models will be done. Finally, it is intended o evaluate the acquired
data and compare them with the results of the numerical model.
2. The bridge
The bridge over Jaguari river is a reinforced concrete bridge built in
1999, located in Fernão Dias highway (BR 381), km 946 +300, on the
border between the states of São Paulo and Minas Gerais. Figure 1
shows a view in where it is possible to observe part of the structure.
The bridge consists of five spans (20m, 26m, 30m, 26m and 20m)
supported on six pairs of columns. Its superstructure is continuous,
without joints, presenting a reinforced concrete transition slab on
each ends.
The longitudinal axis of the bridge has a 5.9% slope towards Belo
Horizonte - São Paulo, also presents constant superelevation of
8% and radius of curvature 305.50 m. Due to the superelevation,
the two girders (GB – greater radius and GA and – smaller radius)
and the pairs of columns present a 50cm depth offset. The loading
is transferred from the superstructure to the columns by rubber
bearing supports .
The superstructure has an overall width of 11.70 m, in which 10.90
m is divided into two carriageways, and 0.40 m is for each rein-
forced concrete New Jersey barriers. The bridge has a π shape
cross-section, with main girders 6.40 m (center to center) apart,
with an individual cross-section of 40cm wide and depth of 2.80 m.
Monolithically connected to the girders, the slab presents variable
thickness, being 15 cm at the end of the 2.65m long cantilever and
24 cm at the center. Besides the curvature in plan and longitudinal
slope, the girders have prismatic variation of the cross section as
they approach the support columns.
The structure consists of 20 transverse beams connected to the
bottom of the main girders, spacing from 6.00m to 6.70m. The
transverse beams over the columns consist of a cross-section of
25 x 220 cm, while the remaining ones consist of 20 x 220 cm.
The columns have circular section (diameter of 120 cm), being
each pair connected by beams (cross section 30 x 80 cm).
The bridge’s infrastructure consists of reinforced concrete cais-
sons (diameter of 140 cm).
3. Hierarchy of numerical models
One of the most common questions related to numerical modeling
concern the accuracy and quality of results. The data to be inserted
while designing model (its geometry, material properties, loads and
boundary conditions) are extremely important in order to create a
representation of the structure in which it is possible to obtain their
structural behaviour (deformation, stress, strain, etc.).
The essence of hierarchical modeling lies on the creation of addition-
al models (and more refined one) of the chosen structure. Aligned
with to the refinement, mathematical equations represent that the
more complex the model is, the harder it will be the solution to con-
Figure 1 – The bridge over Jaguari river
Girder B
Girder A
P4B
Cassion
Column P4A