Combined box girder sea-crossing bridge and construction method thereof

Abstract

The invention discloses a combined box girder sea-crossing bridge and a construction method thereof. The sea-crossing bridge comprises bridge piers and combined box girders supported by the bridge piers; each combined box girder is defined by a high-strength concrete top slab, a superhigh performance concrete bottom plate and a pair of superhigh performance concrete webs; internal and external prestress steel beams are arranged in each combined box girder along the longitudinal direction of the bridge; the combined box girder sea-crossing bridge is simple in structure and good in durability. The construction method comprises the following steps of S1, performing construction of pier foundations, bearing platforms and the bridge piers and precasting channel girders; S2, pouring the high-strength concrete top slab to form one section of combined box girder, and tensioning the internal and external prestress steel beams in the combined box girder; S3, hoisting the combined box girder onto a temporary support; S4, mounting permanent supports and casting adjacent sections of wet jointing seams in situ; S5, demolishing the temporary supports and finishing the system conversion; S6, tensioning internal prestress steel beams in adjacent sections of wet joining seams to form a multi-section continuous girder structure; S7, finishing the bridge surface paving and accessory facility construction. The construction method is simple in process and portable and fast in construction.

Description

technical field [0001] The invention relates to bridge technology, in particular to a combined box girder cross-sea bridge and a construction method thereof. Background technique [0002] Nowadays, most of the non-navigation holes of cross-sea bridges adopt prestressed concrete box girder, steel-concrete composite beam and steel box girder scheme. For example, the approach bridge of the Hangzhou Bay Bridge adopts a 70m prestressed concrete continuous beam scheme, the approach bridge in the tidal flat area adopts a 50m prestressed concrete continuous beam scheme; A 70m prestressed concrete continuous girder scheme is adopted; a 120m steel truss laminated continuous girder bridge and an 85m continuous steel-concrete composite girder scheme are adopted for the non-navigable opening of the Hong Kong-Zhuhai-Macao Bridge. However, there are many problems in these schemes. [0003] Prestressed concrete box girder bridge is the most widely used bridge structure at present. Howeve...

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Problems solved by technology

The problems brought about by this are: the number of foundations increases, which in turn leads to a series of problems such as large impact on water flow, many times of beam erection, and long construction period of beam erection; at the same time, due to the low tensile strength of conventional concrete, in order to increase the span as much as possible diameter, long-span bridges usually increase the cross-section rigidity by increasing the cross-sectional size and plate thickness to meet the structural force requirements, which not only increases the self-weight and project cost of the box girder, but also increases the difficulty of construction; in addition, the concrete Due to the complexity of the force and some reasons in the structural treatment and construction of the web, most of the oblique cracks will appear. Such oblique cracks will not only reduce the rigidity and strength of the bridge structure, but also accelerate the corrosion of steel bars. Reinforcement will cause the expansion of the volume, which will cause the concrete to crack, especially in the weak alkaline environment of the ocean, which will further damage the mechanical performance of the concrete, reduce the durability of the material and the bearing capacity of the structure, and affect the beauty of the bridge and service life

First of all, because the thickness of the plate is too thin, too many internal cables cannot be arranged in this bridge type, so there are many external prestressed cables. Since the external cables are exposed to the air, the durability is poor, which brings maintenance problems and later cable replacement problems. The cost is relatively high; and because the whole bridge uses ultra-high performance concrete, and all the slabs are thin-slab structures, the self-weight of the whole bridge is greatly reduced compared with ordinary concrete box girder bridges. The stress amplitude of the main girder is too large, and the fatigue problem caused by it is worthy of further study, which is not good for the long-term stress of the main girder; since the main girder adopts a thin-plate structure, the bending and torsional rigidity of its section is small, so it must be set Many diaphragms are used to resist the torsion and distortion of the main girder, which will also bring about the difficulty of external prestressing arrangement and steering; The problem of local stress exceeding the limit is also worthy of attention

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