METHOD FOR ERECTION OF PEDESTRIAN OVERPASS Russian patent published in 2000 - IPC

FIELD: bridge building, applicable in erection of new overpasses and reconstruction of existing ones. SUBSTANCE: the method consists in removal of the framework from the existing capital supports, displacement of it afloat to a new axis, making of new capital supports and installation of the framework on them. The novelty is in the fact that at erection of a pedestrian overpass from the existing railway bridge with a double-track steel arched framework of the tie-rod system with two vertical sickle-shaped arch trusses, descending cross stays and struts dividing each arch into thirty equal bays, roadway of two pairs of longitudinal girders attached to the respective crossbeams, before removal of the framework from the existing supports it is subjected to reinforcement, and removal of the framework from the supports, its displacement and installation on new capital supports are carried out by means of three ballasted floating supports in the form of barges forming a floating system, in which the total maximum bulk of ballast is specified proceeding from the condition of provision of maximum probable vertical displacements of the framework joints in the periods of its removal from the existing supports and installation on new supports that are carried out respectively by means of pumping-out of ballast from the compartments of barges with simultaneous use of temporary supports that are erected near the existing capital supports, and pumping-in of ballast into the compartments of barges; in this case use is made of two barges with a single ballasting and power supply system of the same load-carrying capacity, which are interconnected by tie trusses on the deck, and the third barge with a load-carrying capacity exceeding the total load-carrying of the two other barges, maximum draught twice exceeding the maximum drought of the two other barges, and self-sustained ballasting system and power supply system, the framework rests on the barges as a solid asymmetric one with a different distribution of its mass on each barge; pumping-in and pumping-out of ballast are carried out cyclically with measurement of the amount of ballast in all compartments, stresses in the plating and draught of barges; uniformity of ballasting and deballasting, condition of the framework and the design relation of reactions on the floating supports are judged by the results of the obtained information with a subsequent operative introduction of changes in the procedure of ballasting and deballasting. EFFECT: reduced consumption of materials and reduced labour content at erection of a pedestrian overpass due to its use within the constructions of the reconstructed railway bridge; simultaneous provision of pedestrian communication between megapolis districts located on the opposite banks of the river. 14 cl, 38 dwg