2. OBJECTIVES

Proposals for the tests were set out in Gifford Report, ‘Proposed Monitoring of Pop Bottle Bridge’(1), October 2003, which were finalised in liaison with the BOF – Masonry Arch Subgroup.

The primary objective of the Supplementary Load tests was to demonstrate the efficacy of the Archtec strengthening system under service loads, namely:

• To validate the use of the ELFEN DE (DE) analytical method to predict serviceability behaviour in un-strengthened and strengthened arches.
   
• To demonstrate that the retrofitted anchors contribute to the structural behaviour under service loads and that the effects are beneficial and measurable.
   
• And, if possible, to investigate potential long-term methods for monitoring the continued efficacy of the strengthening based on the dynamic response of the bridge and/or strain measurement of the anchors.

The bridge was to be loaded before and after strengthening using two 18 tonne lorries and instrumented to record intrados strains, vertical displacements and anchor strains in the strengthened bridge.

The optional possibility of investigating longer term methods for monitoring the health of masonry arch bridges based on dynamic response of the structure was identified in the proposal. However expediency of time and cost precluded such an investigation on this occasion.