资源目录
压缩包内文档预览：
编号：65968378
类型：共享资源
大小：7.40MB
格式：RAR
上传时间：2020-04-03
上传人：qq77****057
认证信息
个人认证
李**（实名认证）
江苏
IP属地：江苏
35
积分
- 关 键 词：
-
山西
晋城
某市
新建
二级
公路
设计
- 资源描述：
-
山西晋城某市新建二级公路设计,山西,晋城,某市,新建,二级,公路,设计
- 内容简介：
-
- 1 -The introduction and application of prestressed concreteThe application of the concrete structure about 150 years of history, for human civilization has made great contribution, and with the development of social economy, the performance of mankind to building put forward higher request, ordinary concrete already cannot satisfy the needs of the people of high performance concrete, then shipped born, then aggregates prestressed concrete is one of them.The prestressed concrete and reinforced concrete are obviously different principles. In the design of reinforced concrete beams, regardless of the concrete can be assumed by the tensile strength, caused by tension is moment to resistance, a reinforced by pulling force is between reinforcement and concrete bonding and transfer to reinforced. In a big range for the cracking and deformation speaking, although high strength concrete has good bonding, largely can restore; But in between of concrete and reinforced concrete bonding poor ordinary, it virtually impossible for recovery. On the other hand, in the prestressed concrete, the purpose of prestressed reinforced by rapping or through is specially the anchorage to exert a force of concrete, and therefore all concrete can rise to structure role. Prestressed reinforced is necessary to produce to actively give component in advance, and cracking and add load in larger extent deformation can be restored.However, must pay attention to overloading the cases, when the concrete bending tensile strength of prestressed concrete once more than, the performance is some and reinforced concrete is similar, but also in limit load cases, or flexural members under the condition in the destruction of this condition, demanding resistance strain and stress for ordinary reinforced concrete and prestressed concrete structures are the same. In addition, when prestressed into equal to the performance of pre-stressed beam almost become and reinforced concrete members are the same. Therefore, in between reinforced concrete and there are not only the prestressed concrete ultimate similarities and basic differences.What is the prestressed concrete?In order to improve the anti-cracking performance, component in combination of steel and concrete, steel tension in advance before, make components exert the loading in advance before by a reinforced and tensile stress, and by a pre plus of concrete compressive stress, and the concrete called prestressed concrete.- 2 -Prestressed concrete materialsFor some of the requirements: prestressed reinforced(1) strength to high. The tension stress prestressed reinforced the whole in the component make and use process will appear all sorts of stress losses. The sum of these losses 200N/mm sometimes can achieve above, if the reinforced strength is not high, so tension that was set stress even lose to danger.(2) and concrete to have better rapping. Special ZhangFaZhong prestressed reinforced earlier, with concrete bonding between must have higher since the anchor intensity. For some high intensity smooth steel wire shall pass Nick, pressure wave or kink, make it formed Nick steel wire, wire, wire and snarling wave increase rapping.(3) to have enough plasticity and good processing performance. Steel strength is taller, its plastic is lower. Reinforced plastic is too low, especially when in low temperature and impact load conditions, it may happen brittle fracture. Good processability refers to the good performance, and the welding head anchor plate, platen reinforced head after upsetting does not affect the original mechanical properties, etc.Our common prestressed reinforced have cold pull III reinforced, cold drawn level IV reinforced, lengzha ribbed bars high-strength steel reinforced, and heat treatment etc.The prestressed concrete of concrete for some requirements:(1) strength to high, with high strength reinforced with steel, ensure adapt to play its full role, and can effectively reduce weight and reduce the component section size.(2) shrinkage, creep to small, to minimize the loss of prestress.(3) almost hard and strong, make early early prestress, speed up the construction progress and improve equipment utilization rate.The classification of prestressed concreteAccording to production, the design and construction of the characteristic, prestressed concrete can have different classified.1, first zhang method and the method of after zhangFirst zhang method (pretensioning type) is making prestressed concrete component, at first prestressed reinforced tension pouring concreteOne method; Then zhang method (post - tensioning type) is first to pour out concrete, concrete specified strength prestressed reinforced tension again after a pre plus stress method.2, the prestressed and partial prestressedThe prestressed are using loads, the component section tensile stress - 3 -and will not occur in the concrete namely for total cross-section compression. Part prestressed are using loads, the component section concrete allows appear tensile stress or craze, namely only partially section under pressure. Partial prestressed and divided into two categories: A and B of A kind of means in the use of loads, the component preloading area concrete the tensile stress of normal section of the allowable do not exceed the specified value; Class B is refers to the use of loads, the component preloading area the tensile stress of concrete are section allows more than the prescribed limits, but when the crack appears when the width of no more than allow values. Visible, above is manufactured in accordance with the component with the degree of stress divided.3, have the unbonded prestressed concrete with unbonded prestressedBonded prestressing tendons, refers to the stretches along with concrete binding all around it is wrapped in together, prestressed. Zhang prestressed structure and reserve first grouting reinforcement of 2001-2002 wear post-tensioned pre-stressing concrete structure all belong to such. And unbonded prestressing tendons, refers to freedom, not telescopic, sliding with surrounding the prestressed concrete binding. The structure of the prestressed is coated with rust materials, coat prevent ageing plastic pipe, prevent and concrete binding. Binderless prestressed concrete structure and usually post-tensioned pre-stressing concrete process combined. Binderless prestressed concrete structure with light-weight, construction is simple, fast, corrosion resistance is strong, use a good performance, fire performance meet the requirements, the seismic performance is good, wide application etc. Characteristics.The characteristics of prestressed concrete1) enhance the anti-cracking ability the component. Because bear before the loading of prestressed concrete component tensile crack existing preloading stress exists, so outer loads, only when the prestressed concrete to fully offset tensile and tensile strain is more than concrete ultimate tensile strain, component will craze. While general reinforced concrete structure does not exist, the crack load of prestressed concrete ultimate size only by the tensile strength (for the compressive strength of 1/10 or so), thus anti-cracking ability decision is very low.2) increasing the rigidity of component. Because prestressed concrete component in normal use, load effect next may not cracking standard combination of crack, or only a small concrete is basically a elastic stage work and thus component than ordinary stiffness of reinforced concrete member is increased.- 4 -3) make full use of the high strength materials. As mentioned previously, ordinary reinforced concrete members cannot make full use of high-strength materials. The prestressed concrete structures, and gets prestressed reinforced by pull, then first outer loads further increases, reinforced tensile stress should be and always in high tensile stress state, namely can effectively use the high strength reinforced; And the high strength steel, can reduce the need to section area. Meanwhile, should be as using high strength grade of concrete, reinforced with high strength to suitably, get better economic component section size.4) expand the application range of components. Due to the improved component of prestressed concrete anti-cracking performance, thus can be used for waterproof, resisting penetration and corrosion resistance requirements of the environment; Using high strength materials, the structure to be dexterous, stiffness big, can be used in large distortion, the span, heavy load and load under repeated the structure.Prestressed concrete has been widely applied to industrial and civil building and transportation construction. For example 冂 form hollow prestressed floor, roof, roof beam, truesses, crane beam, pre-stress Bridges, railway sleeper already used in great quantities such as. In hydraulic structure also has spent in building docks, zhanqiao pier, pile, gate, DiaoDuShi, pressure conduit, aqueduct, circular pool, working bridge, the road, hydropower station workshop on r.c.roof beam and crane beam structure component, also can used for the method to reinforce the prestressed dam, tunnel lining. For some have unique requirements, such as the structure to prevent water corrosion sea platforms, high temperature and high pressure resistance of nuclear power plant to large pressure vessel etc, adopt prestressed concrete structure is more its superiority, instead of other structure can match.As mentioned above, prestressed concrete structure has a lot of advantages, but also has certain limitation, thus cannot completely replace common reinforced concrete members. Prestressed concrete has the construction process of construction, high technical requirements and needs tension equipment, anchor jig and labor costs higher characteristic, therefore particularly applicable to general reinforced concrete structural strength cannot and circumstances (such as a large span and heavy load structure); While general reinforced concrete members are more convenient, cost due to construction characteristics, applied to lower the cracks allowed general engineering structure, work still has strong vitality.Prestressed concrete efficiencyPrestressed concrete and ordinary concrete can be compared with less - 5 -when the concrete and reduce 1/5 1/3 of the reinforced dosage; But steel unit price difference is not and weight difference in proportion. Prestressed reinforcement and prestressed concrete requirements high strength and high quality, thus each material than the unit price of reinforced concrete the materials needed unit price high. Provisional supports and template may be more expensive, and must take into account the additional charges for prestressed operation itself. But generally speaking, if you need a lot of precast prestressed component, the reinforced concrete and prestressed concrete component in unit price difference between becomes small. In addition, by prestressed indirect saving often is significant, also should be fully considered. These indirect saving including reduced maintenance work or completely avoid maintenance, and because of the durability of the structure have better (due to no permanent craze and increase durability), so that prolong the life; Reduce supporting structure and foundation of the static weight bear; Can achieve large span and reduce bearing; Reduce the height of the structure (or have the same height of larger span).Prestressed concrete in the application of bridge construction1. Prestressed concrete application in bridge componentPrestressed concrete in todays bridge concrete members have been fully in the application and development of small and medium-sized Bridges, both in, or in extrordinarily huge bridge, from one-way prestressed development to two-way, three, can say to the prestressed prestressed has everywhere. Repair highways built Bridges over the mountains, needed more. In addition to the terrain restrictions must be built large span bridge outside, considering the economic reasons, repairs the beam bridge, for in the large-span bridge peg20m, using prestressed concrete, first zhang method using more than 20m paper.through creaks prestressed concrete structure after zhang method. Judging from recent highway construction, using the most is 30 50m prestressed girder method after model T zhang.First prestressed concrete beams and slabs zhang method utilized fully.according tension, must have the huge prestressed reinforcement to withstand a retraction force, need to have enough tension pedestal, the strength, stiffness and stability. Therefore, the initial investment cost more. But first zhang method construction process simple, prestressed reinforced with steel of concrete by or bp, it saves the since anchor to this method the anchorage and clip piece, temporary fixed by use of the anchorage and tension pedestal can be reused.Zhang method after prestressed concrete component is by the anchorage to transfer and keep the add stress gets. The anchorage is to - 6 -guarantee the safety and reliability of prestressed concrete structures, one of the key technology of the design and manufacture of the anchorage, and we used in construction of the anchorage, choice must meet the following requirements:(1) force safe and reliable.(2) the loss of prestress small.(3) the simple structure, easy fabrication, steel quantity is little, and cheaper prices.(4) construction, the equipment is simple, convenient, quick drawing anchorage.The anchorage type varied, in recent years we construction 30 50mT type beam and continuous rigid frame use the Erlenmeyer the anchorage (OVM the anchorage of prestressed strands to anchorage, its type on a variety of types, such as 419 hole with metal or plastic corrugated pipe to the formation of steel duct after zhang reserve. When concrete design strength can be reached in the piping drawing strand. Then shall immediately to hole pressure water injection, to prevent mud prestressed steel corrosion. Also make the prestressed concrete beam combining with the body as a whole, give full play to the effect of prestressed reinforcement. This construction simple and highway bridge engineering nowadays many are using this method after zhang. Pre-stressed beam.Construction material properties and influenceAfter zhang method for the loss of prestressed pre-stressed beam would affect the following aspects:(1) prestressing tendons and pipe wall of the friction between the pre-stress loss caused;(2) by the anchorage deformation, steel beam retraction of prestress loss caused;(3) to have reinforced and first zhang method of temperature difference between pedestal caused by prestress loss;(4) caused by the concrete elastic compression prestress loss;(5) caused by steel beam stress relaxation of prestress loss;(6) the concrete shrinkage and creep of prestress loss caused.Understanding these concrete prestress loss in the construction site, after we must consider these losses, try to decrease the loss value, such as ZhangFaZhong, after the bellows of prestressed control should strictly according to the design, ensure bellows coordinate fixed position accurate, linetypes suitable straight, to minimize value; Choose deformation of smaller the anchorage to anchor, reduce value; Using super zhang bits to - 7 -reduce, value. The concrete shrinkage, creep influencing factors have dosage of cement, cement varieties, aggregate varieties, maintenance condition, concrete production conditions, the use of the environment, etc. Very good choice, use these conditions, can reduce the value of the loss. Prestressed concrete component due after prestress estimates upwards, component has arch degrees, so when construction, component needs to resist against arch degrees set on an prestress value. NaoOrdinary reinforced concrete structural weaknesses and strengths compared(1) improve the resistance to LieDu and rigidity of component. To component prestress, greatly delayed the occurrence of crack, using in the load, does not crack namely is to improve the stiffness, increased structural component of durability.(2) can save materials, reduce weight. Prestressed concrete must adopt high-strength materials, therefore, can reduce the dosage of steel, reduce component section size, saves the massive concrete quantity, to reduce weight, the upper structure of Bridges, especially long-span Bridges, has the remarkable superiority, adopt prestressed concrete is economic and reasonable.(3) reduce the vertical stress and Lord trabecular tensile stress. After used for curve method of zhang prestressed tendons, can make configuration of vertical shear reduce near beam support. Due to the existing preloading, the principal tensile load stress is relatively decreased, and the thickness of the beam can be assembling the thinning.(4) prestressed structure safe and reliable, prestress, is a kind of structure, quality inspection, concrete quality at a glance.(5) improve performance because the structure of prestressed steel work under the existing, the stress caused by load change relatively small. So the possibility of fatigue damage caused by small, this also to withstand the bridge structure dynamic loads is very favorable. But, prestressed concrete component also exist some disadvantages:the construction technology for high quality requirements, complex. Especially the prestress of parts, should be increased to strengthen reinforced to prevent stress concentration, and increases the complexity of construction；need some special equipment. Such as tension jacks and grouting machine equipment. Should also have first zhang method after drawing pedestal, need lots of the anchorage zhang method etc:against arch degrees prestressed, not easy to control deck pavement is uneven and driving setbacks.- 8 -Epilogue(1) although prestressed concrete structures have above some shortcomings, but its advantages are still dominant, has now been broadly applied. Especially in the large span bridge or heavy load structure, and dont allow cracking structure, bridge span from 20. As the development of the beam bridge to the 1000m span bridge, the cable-stayed bridge structure, prestressed concrete use is full embodiment.(2) to give full play to the superiority of the prestressed structure. According to local conditions, and rationally applied to various engineering, let prestressed concrete structure shows it the important position in engineering structure.- 9 -预应力混凝土的介绍和应用混凝土结构的应用大约有 150 年的历史，为人类的文明发展做出了巨大的贡献，而随着社会经济的发展，人类对建筑的性能提出了更高的要求，普通混凝土已不能满足人们的需要，随之各种高性能混凝土便蕴运而生，预应力混凝土就是其中一种。预应力混凝土和钢筋混凝土在原理上有明显的不同。在设计钢筋混凝土梁时，可假定不计混凝土的抗拉强度，因弯矩引起的拉力是由钢筋来抵抗，此拉力是藉钢筋与混凝土之间粘结性而传递给钢筋的。对于在大范围内的开裂和变形来说，虽然高强度的混凝土具有良好的粘结性，很大程度上可以恢复；但是在混凝土与钢筋之间粘结较差的普通混凝土中，则实际上不可能恢复。另一方面，在预应力混凝土中，采用预应力钢筋的主旨在于通过粘结力或者通过专门的锚具给混凝土施加一个力，因此全部混凝土可以起到结构的作用。要求产生预应力的钢筋被用来主动地给构件以预加荷载，而且开裂和变形在较大的程度上可得到恢复。然而，必须注意超载的情况下，当混凝土的弯曲抗拉强度一旦被超过，预应力混凝土的性能就有些和钢筋混凝土相类似，而且在极限荷载情况下，或者抗弯构件在破坏条件下，要求抵抗这种条件的拉力和压力对于普通钢筋混凝土和预应力混凝土构件都是一样。此外，当预应力变为零时，预应力构件的性能几乎变成和钢筋混凝土构件相同。因此，在钢筋混凝土和预应力混凝土之间不但有根本相似之处，也有根本的不同。那什么是预应力混凝土呢？为了提高构件的抗裂性能，在钢筋与混凝土结合之前，预先张拉钢筋，使得构件在施加外荷载之前，钢筋受到一个预加的拉应力，而混凝土受到一个预加的压应力，这种混凝土叫做预应力混凝土。预应力混凝土的材料预应力混凝土的材料对预应力钢筋的一些要求：（1）强度要高。预应力钢筋的张拉应力在构件的整个制作和使用过程中会出现各种应力损失。这些损失的总和有时可达到 200N/mm以上，如果所用的钢筋强度不高，那么张力时所建立应力甚至会损失殆尽。（2）与混凝土要有较好的粘结力。特别在先张法中，预应力钢筋与混凝土之间必须有较高的粘结自锚强度。对一些高强度的光面钢丝就要经过“刻痕” 、 “压波”或“扭结” ，使它形成刻痕钢丝、波形钢丝及扭- 10 -结钢丝，增加粘结力。（3）要有足够的塑性和良好的加工性能。钢材强度越高，其塑性越低。钢筋塑性太低时，特别当处于低温和冲击荷载条件下，就有可能发生脆性断裂。良好的加工性能是指焊接性能好，以及采用镦头锚板时，钢筋头部镦粗后不影响原有的力学性能等。我国常用的预应力钢筋有冷拉 III 级钢筋、冷拉 IV 级钢筋、冷扎带肋钢筋、热处理钢筋、高强钢丝等。对预应力混凝土中混凝土的一些要求：（1）强度要高，以与高强度钢筋相适应，保证钢筋充分发挥作用，并能有效地减小构件截面尺寸和减轻自重。（2）收缩、徐变要小，以减小预应力损失。（3）快硬、早强，使能尽早施加预应力，加快施工进度，提高设备利用率。预应力混凝土的分类预应力混凝土的分类根据制作、设计和施工的特点，预应力混凝土可以有不同的分类。1、先张法和后张法先张法（pretensioning type）是制作预应力混凝土构件时，先张拉预应力钢筋后浇混凝土的一种方法；而后张法（posttensioning type）是先浇灌混凝土，待混凝土达到规定强度后再张拉预应力钢筋的一种预加应力方法。2、全预应力和部分预应力全预应力是在使用荷载作用下，构件截面混凝土不出现拉应力，即为全截面受压。部分预应力是在使用荷载作用下，构件截面混凝土允许出现拉 应力或开裂，即只有部分截面受压。部分预应力又分为 A、B 两类：A 类指在使用荷载作用下，构件预压区混凝土正截面的拉应力不超过规定的容许值；B类则指在使用荷载作用下，构件预压区混凝土正截面的拉应力允许超过规定的限值，但当裂缝出现时其宽度不超过容许值。可见，以上是按照构件中预加应力大小的程度划分的。3、有粘结预应力与无粘结预应力有粘结预应力，是指沿预应力筋全长其周围均与混凝土粘结、握裹在一起的预应力。先张预应力结构及预留孔道穿筋压浆的后张预应力结构均属此类。而无粘结预应力，指预应力筋伸缩、滑动自由，不与周围混凝土粘结的预应力。这种结构的预应力筋表面涂有防锈材料，外套防老化的塑料管，防止与混凝土粘结。无粘结预应力混凝土结构通- 11 -常与后张预应力工艺相结合。无粘结预应力混凝土具有结构自重轻、施工简便、速度快、抗腐蚀能力强、使用性能好、防火性能满足要求、抗震性能好、应用广泛等特点。预应力混凝土的特点预应力混凝土的特点1）提高了构件的抗裂能力。因为承受外荷载之前预应力混凝土构件的受拉区已有预压应力存在，所以在外荷载作用下，只有当混凝土的预应力被全部抵消转而受拉且拉应变超过混凝土的极限拉应变时，构件才会开裂。而普通钢筋混凝土结构中不存在预应力，其开裂荷载的大小仅由混凝土极限抗拉强度（为抗压强度的 1/10 左右）所决定，因而抗裂能力很低。2）增大了构件的刚度。因为预应力混凝土构件正常使用时，在荷载效应标准组合下可能不开裂或只有很小的裂缝，混凝土基本上处于弹性阶段工作，因而构件的刚度比普通钢筋混凝土构件有所增大。3）充分利用了高强度材料。如前所述，普通钢筋混凝土构件不能充分利用高强度材料。而预应力混凝土构件中，预应力钢筋先被预拉，而后在外荷载作用下钢筋拉应力进一步增大，应而始终处于高拉应力状态，即能够有效利用高强度钢筋；而且钢筋的强度高，可以减小需要的截面面积。与此同时，应该尽可能采用高强度等级的混凝土，以便与高强度钢筋相配合，获得较经济的构件截面尺寸。4）扩大了构件的应用范围。由于预应力混凝土改善了构件的抗裂性能，因而可用于有防水、抗渗透及抗腐蚀要求的环境；采用高强度材料，结构轻巧，刚度大，变形小，可用于大跨度、重荷载及承受反复荷载的结构。预应力混凝土已广泛地应用于工业与民用建筑及交通运输建筑中。例如预应力空心楼板、冂形屋面板、屋面大梁、屋架、吊车梁、预应力桥梁、铁路轨枕等已大量采用。在水工建筑中也已用来修建码头、栈桥、桩、闸门、调度室、压力水管、渡槽、圆形水池、工作桥、公路桥、水电站厂房的屋面梁及吊车梁等结构构件，也可用于预应力的方法来加固大坝、衬砌隧洞。对于某些有独特要求的结构，例如需防止海水腐蚀的海上采油平台，需耐高温高压的核电站大型压力容器等，采用预应力混凝土结构更有它的优越性，而非其它结构所能比拟。如上所述，预应力混凝土结构有很多优点，但也存在一定的局限性，因而并不能完全代替普通钢筋混凝土构件。预应力混凝土具有施工工序多、对施工技术要求高且需要张拉设备、锚夹具及劳动力费用高等特点，因此特别适用于普通钢筋混凝土构件力不能及的情形（如- 12 -大跨度及重荷载结构） ；而普通钢筋混凝土构件由于施工较方便、造价较低等特点，应用于允许带裂缝工作的一般工程结构，仍具有强大的
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号