1钢筋混凝土 素混凝土是由水泥、水、细骨料、粗骨料(碎石或;卵石)、空气,通常还有其他外加剂等经过凝固硬化而成。将可塑的混凝土拌合物注入到模板内,并将其捣实,然后进行养护,以加速水泥与水的水化反应,最后获得硬化的混凝土。其最终制成品具有较高的抗压强度和较低的抗拉强度。其抗拉强度约为抗压强度的十分之一。因此,截面的受拉区必须配置抗拉钢筋和抗剪钢筋以增加钢筋混凝土构件中较弱的受拉区的强度。 由于钢筋混凝土截面在均质性上与标准的木材或钢的截面存在着差异,因此,需要对结构设计的基本原理进行修改。将钢筋混凝土这种非均质截面的两种组成部分按一定比例适当布置,可以最好的利用这两种材料。这一要求是可以达到的。因混凝土由配料搅拌成湿拌合物,经过振捣并凝固硬化,可以做成任何一种需要的形状。如果拌制混凝土的各种材料配合比恰当,则混凝土制成品的强度较高,经久耐用,配置钢筋后,可以作为任何结构体系的主要构件。 浇筑混凝土所需要的技术取决于即将浇筑的构件类型,诸如:柱、梁、墙、板、基础,大体积混凝土水坝或者继续延长已浇筑完毕并且已经凝固的混凝土等。对于梁、柱、墙等构件,当模板清理干净后应该在其上涂油,钢筋表面的锈及其他有害物质也应该被清除干净。浇筑基础前,应将坑底土夯实并用水浸湿6英寸,以免土壤从新浇的混凝土中吸收水分。一般情况下,除使用混凝土泵浇筑外,混凝土都应在水平方向分层浇筑,并使用插入式或表面式高频电动振捣器捣实。必须记住,过分的振捣将导致骨料离析和混凝土泌浆等现象,因而是有害的。 水泥的水化作用发生在有水分存在,而且气温在50°F以上的条件下。为了保证水泥的水化作用得以进行,必须具备上述条件。如果干燥过快则会出现表面裂缝,这将有损与混凝土的强度,同时也会影响到水泥水化作用的充分进行。 设计钢筋混凝土构件时显然需要处理大量的参数,诸如宽度、高度等几何尺寸,配筋的面积,钢筋的应变和混凝土的应变,钢筋的应力等等。因此,在选择混凝土截面时需要进行试算并作调整,根据施工现场条件、混凝土原材料的供应情况、业主提出的特殊要求、对建筑和净空高度的要求、所用的设计规范以及建筑物周围环境条件等最后确定截面。钢筋混凝土通常是现场浇注的合成材料,它与在工厂中制造的标准的钢结构梁、柱等不同,因此对于上面所提到的一系列因素必须予以考虑。 对结构体系的各个部位均需选定试算截面并进行验算,以确定该截面的名义强度是否足以承受所作用的计算荷载。由于经常需要进行多次试算,才能求出所需的 3 截面,因此设计时第一次采用的数值将导致一系列的试算与调整工作。 选择混凝土截面时,采用试算与调整过程可以使复核与设计结合在一起。因此,当试算截面选定后,每次设计都是对截面进行复核。手册、图表和微型计算机以及专用程序的使用,使这种设计方法更为简捷有效,而传统的方法则是把钢筋混凝土的复核与单纯的设计分别进行处理。 2土方工程 由于和土木工程中任何其他工种的施工方法与费用相比较,土方挖运的施工方法与费用的变化都要快得多,因此对于有事业心的人来说,土方工程是一个可以大有作为的领域。在1935年,目前采用的利用轮胎式机械设备进行土方挖运的方法大多数还没有出现。那是大部分土方是采用窄轨铁路运输,在这目前来说是很少采用的。当时主要的开挖方式是使用正铲、反铲、拉铲或抓斗等挖土机,尽管这些机械目前仍然在广泛应用,但是它们只不过是目前所采用的许多方法中的一小部分。因此,一个工程师为了使自己在土方挖运设备方面的知识跟得上时代的发展,他应当花费一些时间去研究现代的机械。一般说来,有关挖土机、装载机和运输机械的唯一可靠而又最新的资料可以从制造厂商处获得。 土方工程或土方挖运工程指的是把地表面过高处的土壤挖去(挖方),并把它倾卸到地表面过低的其他地方(填方)。为了降低土方工程费用,填方量应该等于挖方量,而且挖方地点应该尽可能靠近土方量相等的填方地点,以减少运输量和填方的二次搬运。土方设计这项工作落到了从事道路设计的工程师的身上,因为土方工程的设计比其他任何工作更能决定工程造价是否低廉。根据现有的地图和标高,道路工程师应在设计绘图室中的工作也并不是徒劳的。它将帮助他在最短的时间内获得最好的方案。 费用最低的运土方法是用同一台机械直接挖方取土并且卸土作为填方。这并不是经常可以做到的,但是如果能够做到则是很理想的,因为这样做既快捷又省钱。拉铲挖土机。推土机和正铲挖土机都能做到这点。拉铲挖土机的工作半径最大。推土机所推运的图的数量最多,只是运输距离很短。拉铲挖土机的缺点是只能挖比它本身低的土,不能施加压力挖入压实的土壤内,不能在陡坡上挖土,而且挖。卸都不准确。 正铲挖土机介于推土机和拉铲挖土机的之间,其作用半径大于推土机,但小于拉铲挖土机。正铲挖土机能挖取竖直陡峭的工作面,这种方式对推土机司机来说是危险的,而对拉铲挖土机则是不可能的。每种机械设备应该进行最适合它的性能的作业。正铲挖土机不能挖比其停机平面低很多的土,而深挖坚实的土壤时,反铲挖土机最适用,但其卸料半径比起装有正铲的同一挖土机的卸料半径则要小很多。在比较平坦的场地开挖,如果用拉铲或正铲挖土机运输距离太远时,则装有轮胎式的斗式铲运机就是比不可少的。它能在比较平的地面上挖较深的土(但只能挖机械本身下面的土),需要时可以将土运至几百米远,然后卸土并在卸土的过程中把土大致铲平。在挖掘硬土时,人们发现在开挖场地经常用一辆助推拖拉机(轮式或履带式),对返回挖土的铲运机进行助推这种施工方法是经济的。一旦铲运机装满,助推拖拉机就回到开挖的地点去帮助下一台铲运机。 斗式铲运机通常是功率非常大的机械,许多厂家制造的铲运机铲斗容量为8 m³,满载时可达10 m³。最大的自行式铲运机铲斗容量为19立方米(满载时为25 m³),由430马力的牵引发动机驱动。 翻斗机可能是使用最为普遍的轮胎式运输设备,因为它们还可以被用来送混凝土或者其他建筑材料。翻斗车的车斗位于大橡胶轮胎车轮前轴的上方,尽管铰接式翻斗车的卸料方向有很多种,但大多数车斗是向前翻转的。最小的翻斗车的容量大约为5立方米,而最大的标准型翻斗车的容量大约为5m³。特殊型式的翻斗车包括容量为4 m³的自装式翻斗车,和容量约为5 m³的铰接式翻斗车。必须记住翻斗车与自卸卡车之间的区别。翻斗车车斗向前倾翻而司机坐在后方卸载,因此有时被称为后卸卡车。 3结构的安全度 规范的主要目的是提供一般性的设计原理和计算方法,以便验算结构的安全度。就目前的趋势而言,安全系数与所使用的材料性质及其组织情况无关,通常把它定义为发生破坏的条件与结构可预料的最不利的工作条件之比值。这个比值还与结构的破坏概率(危险率)成反比。 破坏不仅仅指结构的整体破坏,而且还指结构不能正常的使用,或者,用更为确切的话来说,把破坏看成是结构已经达到不能继续承担其设计荷载的“极限状态”。通常有两种类型的极限状态,即: (1)强度极限状态,它相当于结构能够达到的最大承载能力。其例子包括结构的局部屈曲和整体不稳定性;某此界面失效,随后结构转变为机构;疲劳破坏;引起结构几何形状显著变化的弹性变形或塑性变形或徐变;结构对交变荷载、火灾和爆炸的敏感性。 (2)使用极限状态,它对应着结构的使用功能和耐久性。器例子包括结构失稳之前的过大变形和位移;早期开裂或过大的裂缝;较大的振动和腐蚀。 根据不同的安全度条件,可以把结构验算所采用的计算方法分成: (1)确定性的方法,在这种方法中,把主要参数看作非随机参数。 (2)概率方法,在这种方法中,主要参数被认为是随机参数。此外,根据安全系数的不同用途,可以把结构的计算方法分为: (1)容许应力法,在这种方法中,把结构承受最大荷载时计算得到的应力与经过按规定的安全系数进行折减后的材料强度作比较。 (2)极限状态法,在这种方法中,结构的工作状态是以其最大强度为依据来衡量的。由理论分析确定的这一最大强度应不小于结构承受计算荷载所算得的强度(极限状态)。计算荷载等于分别乘以荷载系数的活载与恒载之和。 把对应于不乘以荷载系数的活载和恒载的工作(使用)条件的应力与规定值(使用极限状态)相比较。根据前两种方法和后两种方法的四种可能组合,我们可以得到一些实用的计算方法。通常采用下面两种计算方法: 确定性的方法,这种方法采用容许应力。 概率方法,这种方法采用极限状态。 至少在理论上,概率法的主要优点是可以科学的考虑所有随机安全系数,然后将这些随机安全系数组合成确定的安全系数。概率法取决于: 1 Reinforced Concrete Plain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other The plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf the cement/water mix, resulting in hardened The finished product has high compressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its compressive Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to compensate for the weak tension regions in the reinforced concrete It is this deviation in the composition of a reinforces concrete section from the homogeneity of 答题实属不易,请楼主谅解,求采纳~
几年级的啊?
刚好我也在做毕业设计 把我的给你用吧! Traditional Construction ProceduresAs mentioned before, construction under the traditional construction procedure is performed by While they would like to satisfy the owner and the building designers, contractors have the main objective of making a Hence, their initial task is to prepare a bid price based on an accurate estimate of construction This requires development of a concept for performance of the work and a construction time After a contract has been awarded, contractors must furnish and pay for all materials, equipment, power, labor, and supervision required for The owner compensates the contractors for construction costs and A general contractor assumes overall responsibility for construction of a The contractor engages subcontractors who take responsibility for the work of the various trades required for For example, a plumbing contractor installs the plumbing, an electrical contractor installs the electrical system, and an elevator contractor installs Their contracts are with the general contractor, and they are paid by the general Sometimes, in addition to a general contractor, the owner contracts separately with specialty contractors, such as electrical and mechanical contractors, who perform a substantial amount of the work require for a Such contractors are called prime Their work is scheduled and coordinated by the general contractor, but they are paid directly by the Sometimes also, the owner may use the design-build method and award a contract to an organization for both the design and construction of a Such organizations are called design-build One variation of this type of contract is employed by developers of groups of one-family homes or low-rise apartment The homebuilder designs and constructs the dwellings, but the design is substantially completed before owners purchase the Administration of the construction procedure often is Consequently, some owners seek assistance from an expert, called a professional construction manager, with extensive construction experience, who receives a The construction manager negotiates with general contractors and helps select one to construct the Managers usually also supervise selection of During construction, they help control costs, expedite equipment and material deliveries, and keep the work on In some cases, instead, the owner may prefer o engage a construction program manager, to assist in administrating both design and Construction contractors employ labor that may or may not be Unionized craftspeople are members of unions that are organized by construction trades, such as carpenter, plumber, and electrician unions, Union members will perform only the work assigned to their During construction, all work should be For this purpose, the owner, often through the architect and consultants, engages The field inspectors may be placed under the control of an owner’s representative, who may be titled clerk of the works, architect’s superintendent, engineer’s superintendent, or resident The inspectors have the responsibility of ensuring that construction meets the requirements of the contract documents and is performed under safe Such inspections may be made at frequent In addition, inspections also are made by representatives of one or more governmental They have the responsibility of ensuring that construction meets legal requirements and have little or no concern with detailed conformance with the contract Such legal inspections are made periodically or at the end of certain stages of One agency that will make frequent inspections is the local or state building department, whichever has The purpose of these inspections is to ensure conformance with the local or state building Following is a description of the basic traditional construction procedure for a multistory After the award of a construction contract to a general contractor, the owner may ask the contractor to start a portion of the work before signing of the contract by giving the contractor a letter of intent or after signing of the contract by issuing a written notice to The contractor then obtains construction permits, as required, form governmental agencies, such as the local building, water, sewer, and highway The general contractor plans and schedules construction operations in detail and mobilizes equipment and personnel for the Subcontractors are notified of the contract award and issued letters of intent or awarded subcontracts, then are given, at appropriate times, notices to Before construction starts, the general contractor orders a survey to be made of adjacent structures and terrain, both for the record and to become knowledgeable of local A survey is then made to lay out Field offices for the contractor are erected on or near the If desirable for safety reasons to protect passersby, the required to be removed from the site are demolished and the debris is carted Next, the site is prepared to receive the This work may involve grading the top surface to bring it to the proper elevations, excavating to required depths for basement and foundations, and shifting of utility For deep excavations, earth sides are braced and the bottom is Major construction starts with the placement of foundations, on which the building This is followed by the erection of load-bearing walls and structural Depending on the height of the building, ladders, stairs, or elevators may be installed to enable construction personnel to travel from floor to floor eventually to the Also, hoists may be installed to lift materials to upper If needed, temporary flooring may be placed for use of As the building rises, pipes, ducts, and electric conduit and wiring are Then, permanent floors, exterior walls, and windows are At the appropriate time, permanent elevators are If required, fireproofing is placed for steel Next, fixed partitions are built and the roof and its covering are put is place,Finishing operations There include installation of the following: ceilings; tile; wallboard; wall paneling; plumbing fixtures; heating furnaces; air-conditioning equipment; heating and cooling devices for rooms; escalators; floor coverings; window glass; movable partitions; doors; finishing hardware; electrical equipment and apparatus, including lighting fixtures, switches, transformers, and controls; and other items called for in the drawings and Field offices, fences, bridges, and other temporary construction must be removed from the Utilities, such as gas, electricity, and water, are hooked up to the The sit is landscaped and Finally, the building interior is painted and The owner’s representatives then give the building a final If they find that the structure conforms with the contract documents, the owner accepts the project and gives the general contractor final payment on issuance by the building department of a certificate of occupancy, which indicates that the completed building meets building-code 传统的施工程序众所周知,在传统的施工程序中进行施工的承包商。尽管他们想满足业主和建筑设计师的要求,但是最终还是以赚取利润为主要目标的。因此,他们最初的任务是对编写投标价格的建筑成本进行准确的估计。这就需要进行前期调查的工作并且做出施工时间表。等合约批出后,施工方必须提供所有材料并支付其费用,设备,电力,劳动力。业主此时需要进行必要的监督。一个总承包商承担一个建筑整体的责任。从事分包的承建商则需承担建造工程所需的各个工作。例如,管道承包商安装水管,电业承办商安装电气系统,电梯则由电梯承包商安装。他们与总承包商签订合同,费用由总承包商支付。有时候,除了一个总承包商,还有各种专业承包商,如电气和机械承包商,执行工作时需要与业主签订合同。这种承包商被称为间接承包商。他们的工作,由总承包商协调,但它们都是由业主直接联系。还有些时候,业主可以使用设计建造方法同时兼有设计和建筑施工单位的职能。这些单位被称为设计建造承包商。这方面的一个类型的合同聘用的变化是由一户住宅或低层住宅建筑群的开发。在房屋建筑设计和建造的住房,但设计之前需要由购买房屋的业主完成。施工过程管理往往是困难的。因此,一些业主会去寻求专家的协助,这些专家被称为专业施工经理,他们具有丰富的施工经验。施工经理与总承包商进行谈判,并选择其中一个项目。施工经理通常还监督分包商。在施工期间,它们有助于控制成本,加快运送设备和材料,并保持工作的进度。在依法行政,协助设计和建设的情况下,业主可以选择从事建筑项目经理。建筑承包商雇用的劳动力,一般有大工和小工。大工再建筑工程中从事技术活,如木工,管道工,工会成员和电工工会,小工则执行了分配给他们的工作。在施工期间,一切工作都要验收。因此,业主通过建筑师和监理经常进行督查。可能是名为工程员,建筑师或驻地工程师。作为业主的代表实地视察。核查人员必须确保工程符合合同文件的要求,并在安全的条件下进行的责任。这种检查可作出重复。此外,验收还是需要一个或多个政府机构的代表。他们必须确保工程符合法律要求,并负责检查与合同文件是否一致。这种视察一般定期或在某些阶段施工结束以后进行。地方或国家建设部门具有管辖权。这些检查的目的是确保符合当地或国家的建筑规范。以下是传统多层建筑施工的基本程序。建造开始后合同授予开发商,业主可要求开发商开始施工之前签约给或之后签约发出书面通知的同时另一部分工作继续进行。紧接着施工方根据需要获取建筑许可证,例如当地的建设,供水,污水处理,政府机构和公路部门。总承包商的计划和进度详细施工作业以及动员项目设备和人员。分包商得到通知后,做出签订合同的意向或授予分包合同书,然后给出在适当的时候进行通知。在施工前启动,总承包商要进行的一项调查就是邻近结构和地形,这些都要记录在案,并要熟悉当地情况。这项调查结束以后,随即进行布局建设。承建商的现场办事处都建在施工现场或附近。为了安全起见,必须从脚手架上移除的东西,产生的碎片都要运走。下一步,该网架是为建设工程准备的。这项工作为地下室开挖和基础开挖的深度,以及公用事业管道转移找到正确的标高。深挖掘,土方支撑,底部排出。建筑开始于基础上,然后是承重墙和结构框架的施工。梯子,楼梯,或电梯的安装,可让施工人员往返于各个楼层。此外,可安装卷扬机来运送材料。由于建筑高度的上升,管道,电力管道和线路安装以及永久地板,外墙,窗户和构造的影响。在适当的时候,永久的电梯安装。再需要的情况下可以安装防火卷帘。其次,屋顶等地方也需要安装。精加工工序安装有包括以下内容:天花板,瓷砖,墙板,墙壁镶板,水管装置,加热炉,空气调节设备,加热和冷却室装置;自动扶梯;地板,窗户玻璃;活动板,门;电气设备和仪器,包括照明灯具,开关,变压器,控制器,遵照项目的图纸和规格。外地办事处,围栏,桥梁和其他临时建筑,公共设备,如天然气,电力管道,水管,都连接到建筑上。最后,是建筑物内部的打扫和清洗。业主的代表,会给建设工程作最后检查。如果他们满意并认为符合合同文件,那么业主接受该项目,并交给总承包商的一个占用证书,这表明,总承包商已完成建设,建设部门再根据建筑规范的要求发放最后付款。请采纳。