【正文】 shape reinforcing bar, cut down this place way, section of size design and cut with scissors at the same time to adopt often to design to cut with scissors, theory calculate place this can store curved square in, but reality should is it can resist curved still to cut with scissors, so that present the crack and cause the reinforcing bar corrosion. (2)Bridge structure is it dig trough, turn on hole, set up ox leg, etc. to need often, difficult to use a accurate one diagrammatic to is it is it calculate to imitate to go on in calculating in routine, set up and receive the strength reinforcing bar in general foundation experience. Studies have shown, after being dug the hole by the strength ponent, it will produce the diffraction phenomenon that strength flows, intensive near the hole in a utensil, produced the enormous stress to concentrate. In long to step prestressing force of the continuous roof beam, often block the steel bunch according to the needs of section internal force in stepping, set up the anchor head, but can often see the crack in the anchor firm section adjacent place. So, if deal with improper, in corner of ponent form sudden change office, block place to be easy to appear crack strength reinforcing bar of the structure. In the actual project, stress crack once produced the most mon reason which loads the crack. Stress crack once belong to one more piece of nature of drawing, splitting off, shearing. Stress crack once is loaded and caused, only seldom calculate according to the routine too, but with 本 科畢業(yè)設(shè)計 英文文獻 8 modern to calculate constant perfection of means, times of stress crack to can acplish reasonable checking putations too. For example to such stresses 2 times of producing as prestressing force, creeping, etc. , department39。 It is simply little and 本 科畢業(yè)設(shè)計 英文文獻 7 assigning the mistake for reinforcing bar to set up。 this may affect the structural form selected, i. e. whether or not a tie should be introduced, or the stiffness of the deck relative to the arch. In recent years, the traffic capital construction of our country gets swift and violent development, all parts have built a large number of concrete bridges. In the course of building and using in the bridge, relevant to influence project quality lead of mon occurrence report that bridge collapse even because the crack appears The concrete can be said to often have illness ing on while fracturing and frequentlyoccurring disease , often perplex bridge engineers and technicians. In fact, if take certain design and construction measure, a lot of cracks can be overe and controlled. For strengthen understanding of concrete bridge crack further, is it prevent project from endanger larger crack to try one39。 this, of course is not true – but the extent to which it is not true should be of concern to the designer/assessor. Even in the case of a threehinged arch which ostensibly is statically determinate the ?pins‘ are capable of transmitting shear even though they theoretically cannot transmit moments. In the case of nonuniform transverse distribution of loading the hinges will transmit a varying shear which will produce torsion in the arch. Moreover, in the case of skew arches or nonvertical ribs the structure has a much higher redundancy and hence will require greater attention to detail in regard to the releases which are engineered into the structure. From an aesthetic point of view, arches have a universal appeal. In spite of this, care must be taken as the impact of even modest sized bridges is significant. Filled arches are invariably masonry (or widening of masonry) bridges. Cleanness of line, honesty of conception and the attention to detail are vital ingredients to a successful bridge. Certainly, simple stringcourses and copings are preferable to elaborate details which would be expensive and inappropriate for most modern bridges. Where stone is used it is important to be sensitive to the nature of the material. Modern quarrying techniques should be employed (laser cutting, diamond sawing, flame texturing and sandblasting) reserving traditional dressing to conservation schemes. If brickwork is used different textured or coloured bricks and mortar can be specified. Here stringcourses can be particularly useful to mask changes in bedding angle. Historically abutments prised either rock, or else were massive masonry supports relying on their weight to resist the thrust of the arch. In terms of structural honesty this is necessary as it is instinctive to expect such support. Reinforced concrete and steel arches are altogether much lighter structures. ?The structure consists basically of the arch, the deck and usually some supports from the arch to the deck – in that order of importance. These elements should be expressed in both form and detail, and with due regard for their hierarchy‘ (Highways Agency, 1996). It is important that the deck, if it rests on the crown of the arch, should not mask it in any way. Any support whether spandrel columns or hinges (in the case of the tied arch) should not be allowed to dominate. Preferably they should be recessed relative to the parapet and stringcourse. Concrete arches can be either a full width curved slab or a series of ribs. Steel is almost 本 科畢業(yè)設(shè)計 英文文獻 6 always a series of ribs. Where ribs are used thought should be given (if they are going to be seen from underneath) to the chiaroscuro of the soffit. The ratio of span to rise should generally be in the range 2:1 to 10:1. The flatter the arch the greater the horizontal thrust。 It is insufficient to design the section。 Receive the contact, striking of the vehicle, shippi