NDT TESTS ON AN EXISTING R.C. BRIDGE: HOW TO MANAGE DIFFERENT TEST CAMPAIGNS
September 8, 2017, ITT Madras, Chennai, India
Biondi S.(1), Cataldo N.(1) and Zuccarino L.(1)
(1) INGEO, Chieti-Pescara University, Italy
Abstract ID Number (given by the organizers): …………..
Keywords: concrete core compressive tests, creep response of r.c. elements, existing R.C. bridge, laser scanning and topographic levelling for structural analysis, loading tests on road bridges, NDT tests
Author contacts
Authors E-Mail Fax Postal address
Samuele Biondi s.biondi@unich.it +39.085.4537.255 Dipartimento inGeo, viale Pindaro n. 42, 65127 Pescara (Italy)
Nicola Cataldo nico984@libero.it +39.085.4537.255 Luigia Zuccarino l.zuccarino@unich.it +39.085.4537.255 Corresponding author for the paper: Samuele Biondi
Presenter of the paper during the Conference: Samuele Biondi
Page 1 NDT TESTS ON AN EXISTING R.C. BRIDGE: HOW TO MANAGE DIFFERENT TEST CAMPAIGNS
Biondi S.(1), Cataldo N.(1) and Zuccarino L.(1)
(1) INGEO, Chieti-Pescara University, Italy Abstract
An interesting case study is discussed in this paper that could represents a yardstick in the approach to an existing structure. In this case an isostatic (Gerber scheme) prestressed r.c. bridge is considered; this scheme is quite usual for simple bridge. In present paper a particular situation is discussed. The bridge was built in 1970 as an element of a series of similar bridges. During his service life it suffered poor structural maintenance and it shown transverse and longitudinal displacements that were considered unacceptable for its use. So four series of different structural tests (both non destructive and partial destructive [concrete cores], both static and dynamical load) were carried out. Results of these tests are evaluated independently each other by different Authorities and regardless real structural scheme and viscous behaviour in concrete. So wrong conclusions were carried out and in 2012 the bridge was assumed near collapse. In 2013 the Local Authority (Chieti Municipality) ordered a new series of static test and structural analysis. By means of a correct management of previous results and coherent, but simple, structural model, it had possible to detect a security level that is adequate to original design provisions and to previous Code. A simple recalibration of load capacity was carried out, according to actual structural Code. Now the bridge is on duty regularly and a maintenance program will start in the near future.
1. INTRODUCTION
The urban and infrastructural contest of the investigated bridge in shown in Figure 1, in the same figure a statement of the original design drawings is shown. Due to the fact that Local Authority asked to carry out the new test series without closing the local road traffic, terrestrial laser scanner surveys were carried out in order to identity the bridge geometry, Figure 2. All previous tests and structural analyses were collected, Figure 3, and a new static load test was carried out, Figure 4, after a correct management of the previous test results.
Figure 1: Actual bridge plan configuration and 1970 design provisions
Chieti-Pescara Highway
Dragonara Bridge (km 8+000)
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Figure 2: bi & three-dimensional point clouds of bridge from terrestrial laser scanner surveys
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Figure 3: First (1999) series of NDT and core extraction tests (up) and static load tests (down)
Figure 4: transverse & longitudinal displacements at various ages (left) and at maximum load (2014 static load test - right - dSAP solid lines are FEM provisions after material identification)
2. CONCLUSIONS
If viscous response and age of concrete are considered in relation to load time, a correct management of different test campaigns permitted to evaluate the concrete characteristics (strength and stiffness). In this manner a simple (linear) FEM model permits to provide structural response to a load test for the investigated bridge. The efficiency of this provision guarantees the correctness of structural model. The bridge was assumed near collapse while now is on duty and a maintenance program will start in the near future.
-100 -80 -60 -40 -20 0 20 40 -2 2 6 10 14 18 22 26 30 34 38 42 46 [ m m ] [m]
Piano quotato relativo allineamento medio (direzione Sud-Nord)
06/03/2003 03/07/2012 30/08/2013 16/09/2014 17/09/2014 d SAP d visc -12 -10 -8 -6 -4 -2 0 2 4 6 -2 2 6 10 14 18 22 26 30 34 38 42 46 s p o s ta m e n to [ m m ] ascissa [m] Certificato 2014/001/09 passo 08 passo 08 bis passo 09 dSAP P = 557,300 kN
