Sinking of AM - 50 Bridge

Abstract

AM � 50 trestle bridge affords an excellent bridge capability and is worth mentioning due to it�s high maneuverability, simplicity in launching operation and economy in time and manpower for launching operation. Twenty-seven AM - 50 bridges were procured from Czechoslovakia. The problem of differential / normal sinking of trestle shoes, experienced during various exercises conducted in the recent past, has exposed a serious short fall compromising the versatility of AM � 50 bridge. The sinking of any trestle shoe can make the bridge unusable and also creates problem in the functioning of trestles. Retrieval of sunken trestle shoe is also problematic for recycling of the bridge during critical stages of operations. The objective of this study is to review the sinking problem and recommend some modification in the bridge to make it suitable for the environments of low bearing capacity soils. Determination of the bridge response to moving loads is indispensable for bridge users and bridge design engineers. Dynamic analysis of the bridge was performed so that bridge trestles, shoes and soil interaction is thoroughly explored. In addition to this a complete reverse engineering process was carried out for properties of materials and geometry, since the vendor has not furnished the data required for analysis. The bridge shoes were designed as substructures to facilitate the design and analysis. To ensure accuracy, a number of shoe sizes were considered and analyzed for sinking. A prototype shoe size was selected and than designed as a shell structure. The designed shoe extension will facilitate use of this bridging asset in soils of bearing capacity as low as 0.5 TSF.