资料简介： Bridge Types of discussion
Arch，After girders, arches are the second oldestbridge typeandaclassic structure. Unlike simple girder bridges, arches are well suited to the use of stone.Manyancientandwellknow examples of stone arches still stand tothis day. Arches are good choices for crossing valleys and rivers since the arch doesn't require piers in the center. Arches can be one of the more beautiful bridge types.Arches use a curved structure which provides a high resistance to bending forces. Unlike girder and truss bridges, both ends of an arch are fixed in the horizontal direction (i.e. no horizontal movement is allowed in the bearing). Thus when a load is placed on the bridge (e.g. a car passes over it) horizontal forces occur in the bearings of the arch. These horizontal forces are unique to the arch and as a result arches can only be used where the ground or foundation is solid and stable.
Like the truss, the roadway may pass over (illustration #1) or through an arch (illustration #4) or in some cases both (illustration #3.) Structurally there are four basic arch types: hinge-less, two-hinged, three hinged and tied arches.
桥梁类型的探讨
拱桥，拱桥是继桁架桥之后，第二个最古老的桥类 型，具有典型结构。不像单梁桥，拱桥适合 用石头砌。许多古代的好的石拱桥沿用至今，因为中心不需要桥墩，拱桥是横越ft谷和河川的最好选择。拱桥可能是一种较美丽的桥类型。拱桥使用提供高抗弯力的弯曲结构。不像桁和梁架桥,水平力在桥的两端得 到削减 (也就是 没有允许水平运动的轴承).当桥上有负荷时，(如 一辆小汽车 从桥上通过时)拱的轴承上产生了水平向上的力。由于这种独特性拱桥仅仅用在 那些地基比较稳固的地方。
像梁架桥, 前面可能在上（例证 #1)或经过一个拱 (例证 #4)，某些情况下 两者都有 。(例证 #3) ，结构上拱桥有四种基本类型: 铰-少量（单铰）,双铰, 三铰和系拱桥。
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