PSI - Issue 5

C.A. Prato et al. / Procedia Structural Integrity 5 (2017) 332–339 C.A. Prato/ Structural Integrity Procedia 00 (2017) 000 – 000

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1. Introduction

The foregoing work aims at evaluating the current state of practice for assessment of design of a new three-pylon stayed bridge for a major national highway from the stand point of pedestrian comfort. The focus is not on the feasibility or merits of this particular bridge configuration, but on the procedures used at design stage to warrant that traffic induced accelerations at pedestrian sidewalks satisfy code-prescribed regulations. The approach adopted to assess the new design was to carry out a series of standard dynamic tests of an existing bridge of similar structural scheme regarding deck configuration and stays. The configuration of the new bridge is shown in Figure 1 with main spans of 60 m, while that of the existing and tested bridge with 30 m main spans is in Figure 2; these bridges have the same type of deck and erection procedure. Their structure consists of pre-fabricated pre-stressed concrete beams, cast in-place concrete slab typical of standard simply supported structures, in which alternate intermediate pillards are demolished after erection and replaced by the stays to provide the vertical reaction. Since the national code for design of highway bridges of Argentina does not include specific requirements for comfort prediction or assessment, the procedure given by the Spanish Code IAP-11 [1] was adopted by the designer, although it explicitly states that the simplified procedure of passing a reference vehicle does not apply for main spans larger than 50 m. To comply with the code requirements, a more exhaustive evaluation of the vibrations induced by traffic was decided by carrying the tests described here in the existing bridge, which at least in terms of span length complies with the requirement of the IAP-11 code regarding the applicability of the simplified calculations at design stage for assessment of pedestrian comfort.

Fig. 1. Schematic representation of the new bridge at design stage

Fig. 2. Schematic representation of the SAP2000 model of tested bridge

2. Test Program Two types of tests were carried out:

 Impulsive tests to measure damping.