Slant leg rigid frame built-in prestressed concrete variable cross-section box girder bridge and construction method thereof

Abstract

The invention discloses a slant leg rigid frame built-in prestressed concrete variable cross-section box girder bridge. The bridge comprises piers, and bottom plates and web plates forming a box girder; a slant leg rigid frame structure is arranged in a variable cross-section girder bridge box, and comprises internal longitudinal beams and internal aslant legs; upper bend anchoring plates upwards inclined along the longitudinal direction of the box girder from the midspan to the pier direction are arranged above the internal longitudinal beams; midspan sagging moment bottom plate ropes are arranged along the upper bend anchoring plates and upper bends of the internal longitudinal beams to form two layers of bottom plate ropes; sawtooth blocks are arranged at the tension anchoring positions of the bottom plate ropes on the internal longitudinal beams and the upper bend anchoring plates; and the tension anchoring ends of the bottom plate ropes are bent in the box at the sawtooth blocks. The bridge structure provides reasonable rope arrangement and anchoring positions to the sagging moment ropes so as to reduce the bottom plate section hollow rate and the bottom plate rope flat bending amplitude. The sagging moment bottom plate ropes generate the upward radial force to eliminate or reduce the influence of the second-phase dead load causing the girder down-warping deformation. The invention further discloses a construction method for the slant leg rigid frame built-in prestressed concrete variable cross-section box girder bridge.

Description

technical field [0001] The invention relates to the technical field of civil engineering bridges, more specifically, to a prestressed concrete variable-section box girder bridge with built-in oblique-leg rigid frame and a construction method thereof. Background technique [0002] Long-span prestressed concrete variable-section box-girder bridges are widely used bridge types at present, and continuous beams and continuous rigid-frame bridges are the most common, and they are often constructed by hanging basket cantilever casting method. figure 1 It is a facade layout diagram of a long-span prestressed concrete variable cross-section box girder bridge in the prior art. It is a continuous rigid frame bridge. The façade of the lower edge of the main girder is in the shape of a flat arch, and the bridge is constructed using the segmented hanging basket cantilever cast-in-place process. It includes the mid-span closing section 08, the side-span closing section 09, the pier top se...

AI Technical Summary

Problems solved by technology

[0009] (3) It cannot provide an upward component force, and cannot balance the second-phase dead load and the downward force of the lane load

[0010] (4) No control method is provided to eliminate or reduce the deflection deformation of the main girder caused by the second-stage dead load, and the deformation is not easy to control after the main span is closed

[0011] (5) On bridges with two-way longitudinal slopes in the main span, the downward radial force of floor cables 05, the first-phase and second-phase dead loads, and the driveway loads are all downward, which intensifies the shrinkage and creep effect of concrete, resulting in certain continuous downward

[0012] (6) The built-in slanted leg 042 and the box girder floor 01 are arranged in parallel, the radial distance between the built-in slanted leg 042 and the bottom plate 01 is 1 / 4 to 1 / 5 of the total beam height H of the fulcrum, and the built-in longitudinal beam 041 and built-in The distance between the inclined legs 042 is too large, exceeding 5 to 6 meters, and the stability of the web 02 and the torsional capacity of the box girder are not good

[0013] (7) The problem of a sharp increase in the horizontal hollowing rate of the prior art floor is not solved

When the span increases, the effective load-carrying section decreases sharply, which may lead to cracking or cracking of the bottom plate

[0017] (8) The problem of the cracking of the bottom plate directly caused by the horizontal force and tension generated by the excessive flat bending in the prior art is not solved

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