GB1398435A - Concrete bridges - Google Patents

Abstract

1398435 Concrete bridges M SCHUPACK 6 July 1972 [8 July 1971] 31836/72 Heading E1G In a concrete bridge overpassing a roadway 72a, b Fig. 5 at a skew angle and incorporating longitudinally-spaced pre-cast longitudinal beams such as box beams 20, Fig. 1, united by transverse diaphragms 26, 28 of in situ concrete to form a span which is rectangular in plan, the rectangular bridge span extends between obtuse-angled end abutments each comprising a wall 30 normal to the span and a raked wall 32 parallel to the skew road 72a, b, the span being supported over a major part of its width on bearings 74 on the wall 30 while the remainder of its width is laterally cantilevered, and the abutment walls have an integral capping slab 34 which forms a continuation of the bridge span, the slab 34 being cantilevered beyond the raked wall 32 and having an end face in opposed parallel relationship with the end face of the bridge span to provide a straight expansion gap 40. The bridge shown has three laterally-spaced rows of pre-cast open-topped box beams 20 each provided with peripheral upstanding wooden flanges 48, Fig. 11 (see also Fig. 2, not shown), which are out on site to the required height to support five rows of thin prefabricated reinforced concrete slabs 22 according to the transverse and longitudinal deck curvature required. The beams and slabs are unified by in situ concrete 89 forming the roadbed and the transverse diaphragms 26, 28. There are in each row four box beams 20, Fig. 6 (not shown) on each side of a central cast-in-situ pier (84). The walls of the box beams have bores providing throughout the bridge length a sinuous conduit for post-tensioning cables (57), the bores being such, Fig. 11; that the cables rise and fall respectively in the outer beams 20a, 20c of each four, but run horizontally in the two intermediate beams 20b Fig. 11 also illustrates the rubber bridge bearings 74 and a transverse expansion joint 92 over the gap 40. The bridge, Fig. 1, includes an overhung sidewalk and parapet 24 constructed from L-section precast concrete members (62-64, Figs. 4, 10 not shown) united with the road section by in situ concrete (87). The Specification illustrates, Fig. 6 (not shown) some (82) of the temporary formwork required; some, Figs. 9, 10 (not shown) of the steel reinforcement (e.g. transverse post-tensioning cables (45)) and details of kerb blocks (88), service conduits (86) and screen fences (19). The Specification also describes the casting of the prefabricated box beams and the sequence of bridge construction. In a modification the thin pre-cast slabs 62 are replaced by removable joists and shuttering boards.