THE ASSESSMENT OF A MULTI-SPAN MASONRY ARCH BRIDGE

This paper contains the assessment of a multi-span masonry arch bridge. It brings together the single span assessments coupled to previous and recently developed multi-span factors, current checks on pier adequacy, empirical multi-span assessments and theoretical multi-span analyses. The approach adopted in the paper is that of assisting an assessing engineer undertaking a regular assessment to a real structure. The geometric shape of the structure was chosen as typical of many masonry bridges found in the UK. Whilst all the geometric parameters were fixed, consideration is given to the effects of changes in the size of the supporting piers on the results of the multi-span assessment. The paper includes for a multi-span arch, the single span assessment using the computerised Pippard/MEXE, mechanism and elastic cracking methods. The paper then goes on to investigate the size of pier required to ensure single span behaviour using (a) a 7 pin double span analysis (b) a recent multi-span regression analysis (c) Fmult as determined from two pieces of recent research and (d) the method in BD 21/93. Finally conclusions are presented on the ease of application of the different approaches and the value of the respective results. (A)