Title: IMPLICATIONS FOR ASSESSMENT FROM HALF-SCALE MODEL BRIDGE TEST
Abstract: The implicit conservation built into design codes leads to the belief that bridges are stronger than the codes allow. This paper presents evidence from a collapse test on a half-scale deck at the Transport and Road Research Laboratory. The bridge of eight precast pre-stressed beams with a precast in situ slab designed to conform with BS 5400: Part 4 (see IRRD 282725), was tested under dead load, superimposed dead load and live load, as specified in BS 5400: Part 2 (1978) (see IRRD 235663). It was loaded to collapse by increasing the abnormal vehicle load until failure occurred. The primary cause of failure was shear in the precast beams with shear-links fracturing shortly before collapse. Results showed that linear grillage analysis produced acceptable results for load effects with a small reserve of strength present. The design was shown to be conservative, but margins may not be large. The model failed in beam shear at 3.17 times the HB (abnormal vehicle) load where the unfactored code calculations indicate failure at 2.8 times. There could be reserves of strength in slab flexure, torsion in the beams and end diaphragm, interfacial shear, web crushing, combined shear/torsion and shear strength close to the support.
Publication Year: 1990
Publication Date: 1990-06-01
Language: en
Type: article
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