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The development trend of China Highway Bridge

Author: Anonymous From: www.yourpaper.net Posted: 2010-06-24 11:55:51 Read:
Author: Zhang Guojie Du Lipeng Xu Guanghai
Abstract: with the economic development, enhance the comprehensive national strength, China's building materials, equipment, construction techniques have developed rapidly.Especially the extensive application of electronic computing technology, for the vast number of engineering and technical personnel to provide convenient calculation, fast analysis method.More important is the financing channels of China's economic policy to provide diversified development of highway cause, ensure the construction capital source.In this paper, combined with the commonly used bridge to talk about the development trend of highway bridge view, inappropriate, please counterparts.
Keywords: highway bridge; development trend;
Since the reform and opening up, China's highway construction enterprise rapid development, especially the construction of expressway has been completed, from scratch, 8700km.As the bridge construction is an important part of highway construction also obtained the corresponding development, across the river (River), the channel (Bay) grew up bridges were built, bridges, overpasses, in general, highway and highway forms, constantly improve the quality, provide safe, comfortable service for highway transport.
Our country vast bridge workers, fully aware of this valuable, rare opportunity, strain every nerve, play to their one's ability and cleverness, as China Road and bridge construction, work actively, make contribution more.
A type of bridge,
Slab bridge is a common type of highway bridge in large quantity, wide, it is simple in structure, clear force, can the use of reinforced concrete and prestressed concrete structure; can be made into solid and hollow, cast-in-place to meet a variety of curved shape, slope, skew bridge, therefore, the general public roads, highways and city roads bridge, widely used.Especially in the height of the building by the small span bridge, highway and plain region, especially welcome, thereby reducing the height of embankment fill, less arable land and save the earthwork.
Hollow plate for equal to or greater than 13m span, generally adopted pretensioned or post-tensioned prestressed concrete structure.Pretensioned strand and cold drawn steel wire; post-tensioned available single steel wire, steel strand anchor group or a plurality of flat anchorage, formwork cast-in-place and precast.Into the hole by capsule, folding type template or disposable pore-forming materials such as precast concrete pipe or other materials.
Reinforced concrete and prestressed concrete slab bridge, and its development trend is: using high grade concrete, in order to ensure the use of performance as far as possible the use of prestressed concrete structure; prestressing anchorage of prestressed steel and diversification; usually adopts the steel strand.Bridge span can be achieved 25m, currently has built bridge span of 35 ~ 40m.In my opinion, the span is too big, material is not province, plate height, small stiffness, prestressing degree is big, arched high, degree of prestress is small, possible deflection; if the use of prefabricated, transverse connection is not strong, easy problems deck longitudinal cracking when in use.The hoisting capacity increases, the precast hollow slab width has the trend of increase of about 1.5m, width is appropriate.
Two, Liang Shiqiao
Liang Shiqiao and many kinds of highway bridges, is most commonly used in bridge, its span is from 20m till 300m.
Highway bridge common beam bridge forms:
According to the structure of system is divided into: beam, cantilever beam, continuous beam, T type rigid frame continuous rigid frame, etc..
According to the cross section type is divided into: T type beam, box beam (or channel girder truss beam), etc..
This paper from the following several commonly used structure form the use and development trend of Liang Shiqiao in the highway bridges.
(a) simply supported T beam bridge
T beam bridge built up in our country highway, as early as in twentieth Century 50, 60 time, China built many T beam bridge, the bridge to an important role for improving the road traffic in china.
Since 80 time, our country highway built a number of representative of the prestressed concrete simply supported T beam bridge (or continuous deck), such as Henan Zhengzhou, Kaifeng the Yellow River road bridge, Zhejiang province Feiyun River Bridge, its span reached 62m, lifting heavy 220t.
T beam of reinforced concrete structure has very little, from 16m to 5Om span, are used in the precast post-tensioned prestressed concrete T beam.Prestressed system adopts steel strand anchor group, at the site of prefabricated, hoisting erection.And its development trend is: high strength, low relaxation steel strand anchor group: concrete grade 40 ~ 60; T beam flange widening, 25m is suitable; the lifting weight increased; in order to reduce the joint, improve driving, the I-shaped beam, cast-in-place beam end beam wet joints and bridge deck, arrangement of negative bending steel beam in bridge of cast-in-place concrete, formed than continuous deck further "quasi continuous" structure.
Prestressed concrete T beam has simple structure, definite stress, material saving, convenient erection, advantages of large span capacity.The maximum span preferably not more than 50m, then increase the span from stress, tectonic, the economy is not reasonable.More than 50m to select the appropriate span box-section.
(two)
continuous box girder bridge
Box section can adapt to a variety of operating conditions, particularly suitable for prestressed concrete continuous beam bridge, the bridge of variable width.Because the embedded cantilever plate is fixed in the box girder, its length can be greatly changed, and the distance of webs can be enlarged; box girder with large torsional stiffness, therefore, box beam can be built in a single column pier of curved skew bridge; box girder allowable maximum length; stress is low gravity axis, not partial to one side, the same T beam creep deformation is smaller than.
Box girder with single box single room, double room, single box (or room), early is a rectangular box, gradually developed into a trapezoidal box oblique back the.
Box girder bridge can be variable height, can also be highly.From the aesthetic point of view, there are three large span box main hole and the side hole of the beam bridge, with variable beam is more beautiful; multi-span bridge (more than three spans) high box has good appearance effect.
With the rapid growth of traffic volume, speed increase, people travel to want fast, comfortable traffic condition, the prestressed concrete continuous box girder bridge can meet this need.It has a deck joints less, beam height, stiffness, strong integrity, beautiful appearance, convenient maintenance etc..
(three)
continuous rigid frame bridge
One of the prestressed concrete continuous beam bridge continuous rigid frame bridge, the general use of variable cross-section box beam.The highway system in our country began to design, construction of continuous rigid frame bridge from the mid 80, still be just unfolding.
Continuous rigid-frame structure can cross, also can be loosened by side spans, bearing, a continuous rigid-frame structure beam system.A seamless, improved traffic conditions; beam, pier consolidation, no support; a reasonable choice of beam and pier stiffness, can reduce the Liang Kuazhong moment, which can reduce the beam of the building height.Therefore, maintaining the advantages of T shape rigid frame and continuous beam of continuous rigid frame bridge.
Suitable for large span continuous rigid frame bridge, high pier.Using flexible thin-walled high pier, as a column, the main role embedded solid is reduced, the beam force close to the continuous beam.Flexible pier needs to consider the effect of longitudinal deformation and rotation of the girder and the stability of columns; the pier wall thick, is taken as a rigid pier of continuous beam, as framework, pier to withstand the big moment.
Because the force and the use of the characteristics of continuous rigid frame, in the design of long-span prestressed concrete bridge, this bridge is preferred.Of course, the shorter bridge pier, the bridge was limited.
Prestressed concrete continuous rigid frame bridge in China, almost all the cantilever pouring construction.Generally use 50 ~ 60 grade of concrete and prestressed steel beam.
Now, a prestressed concrete are ready to design about 300m span continuous rigid frame, in my opinion, if we can adopt high-strength lightweight concrete material, its span is expected to reach about 300m.Due to the increase in span continuous rigid frame, with the increase of weight, the proportion of dead load has reached more than 90%, so the unilateral increase span, has no practical significance.At this point should be considered in the choice of cable-stayed bridge or other bridge.
Three, reinforced concrete vertical arch
Arch bridge in China has a long history, is China's traditional project, is also one of the large span bridge.
Construction of arch bridge has the largest number of highways in china.The stone arch bridge since major in material processing, time-consuming, large-span stone arch bridge built less.Mountain road
In, bridge and culvert, suit one's measures to local conditions, a stone arch bridge (Han) is appropriate.Long-span arch bridge of reinforced concrete box arch, arch and stiff skeleton of concrete filled steel tubular arch.
Reinforced concrete arch bridge form more, in addition to the mountains, but also suitable for plain area, the following half-through tied arch bridge.Combined with environment, terrain, and the arch of the majestic, beautiful appearance, can create a harmony between man and nature landscape.For example, the Wujiang River Bridge in Guizhou Province, located in the mountains, canyons, the span of the arch bridge 330m bridge 263m, away from the bottom, deck Renli, admirable bridge designers and builders of ingenuity and great.Have just completed Wanxian Yangtze River bridge, stiffness skeleton arch, span 420m, ranking first in the world.Guangxi County Yongning Yongjiang bridge, concrete-filled steel tube arch, span 312m, are commendable arch bridge.
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