Inexpensive Design & Cost Optimization of Spill Through Abutment with Pre-Stressed Superstructure

This thesis presents the executional viability and cost benefits of spill through type abutment with higher embankment height and long spans. The detailed structural design of open footing, substructure and superstructure shall be submitted in this technical paper in order to better understand the structural analysis and behaviour. The Spill-through abutments primarily consists on rectangular or circular type columns placed at intervals to let the soil spill between them. While they do not include wing walls or return walls to retain the soil embankment, the deck is placed/casted on girders rested on bearings. Streams or roadways are to pass between the abutment locations. The width of the abutment cap is based on the accommodation of bearing location and seismic stoppers. When the embankment height is high enough and the existing stream or waterway is undisturbed then spill through abutment is considered more inexpensive and cost optimum than wall type abutment. The open footings are constructed by initially excavating soil upto the bottom of footing. During the initial stages of site execution, the complete open footing is visible and thus is referred to as open foundation. Each footing is intended to carry the load from the individual columns and distribute the same over a larger area, so that the safe bearing capacity of the soil is not exceeded. Pre-stressing or specifically post-tensioning is the application of axial force to increase the moment carrying capacity of concrete or other materials using high strength steel strands or bars, denoted as tendons. Post-tensioning is applicable is a variety of construction sectors including buildings, parking areas, bridges, stadiums, soil anchors, water-tanks, etc to name a few. Although, post-tensioning systems require expertise for fabrication, assembly and installation, the basic application is easily explainable. In many cases, posttensioning allows construction that would otherwise be impossible due to either execution constraints or architectural requirements. A post-tensioning system shows application of tendons which are stretched by hydraulic jacks so that system has no tensile stresses developing at any section and is held in place by anchoring devices.