【五層】4426平米框架教學樓（開題報告、計算書、建筑、結(jié)構(gòu)圖）

【五層】4426平米框架教學樓（開題報告、計算書、建筑、結(jié)構(gòu)圖）,【溫馨提示】壓縮包內(nèi)含CAD圖有預覽點開可看。打包內(nèi)容里dwg后綴的文件為CAD圖,可編輯,無水印,高清圖,壓縮包內(nèi)文檔可直接點開預覽,需要原稿請自助充值下載,所見才能所得,請細心查看有疑問可以咨詢QQ：11970985或197216396 華北水利水電學院畢業(yè)設計鋼筋混凝土素混凝土是由水泥,水.細骨料.粗骨料(碎石或卵石).空氣,通常還有其它外加劑等經(jīng)過凝固硬化而成.將可塑的混凝土拌合物注入到模板內(nèi),并將其搗實,然后進行養(yǎng)護,以加速水泥與水的水化反應,最后獲得硬化的混凝土.其最終制成品具有較高的抗壓強度和較低的抗拉強度.其抗拉強度約為抗壓強度的十分之一.因此,截面的受拉區(qū)必須配置抗拉鋼筋和抗剪鋼筋以增加鋼筋混凝土構(gòu)件中較弱的受拉區(qū)的強度.由于鋼筋混凝土截面在均質(zhì)性上標準的木材或鋼的截面存在著差異,因此,需要對結(jié)構(gòu)設計的基本原理進行修改.將鋼筋混凝土這種非均質(zhì)截面的兩種組成部分按一定比例適當布置,可以最好地利用這兩種材料.這一要求是可以達到的,因混凝土有配料攪拌成濕拌合物,經(jīng)過振搗并凝固硬化,可以做成任何一種需要的形狀.如果拌制混凝土的各種材料配合比恰當,則混凝土制成品的強度較高,經(jīng)久耐用,配置鋼筋后,可以作為任何結(jié)構(gòu)體系的主要構(gòu)件.澆筑混凝土所需要的技術(shù)取決于即將澆筑的構(gòu)件類型,諸如:柱.梁.墻.板.基礎(chǔ),大體積混凝土水壩或者繼續(xù)延長已澆筑完畢并且已經(jīng)凝固的混凝土等.對于梁.柱.墻等構(gòu)件,當模板清理干凈后應該在其上涂油,鋼筋表面的銹皮及其它有害物質(zhì)亦應該清除干凈.澆筑基礎(chǔ)前,應將坑底土夯實并用水浸濕6英寸,以免土壤從新澆筑的混凝土中吸收水份.一般情況下,除使用混凝土泵澆筑外,混凝土都應在水平方向分層澆筑,并使用插入式或表面式高頻電動振搗器振實.必須記住,過分的振搗導致骨料分離和混凝土泌漿等現(xiàn)象,因而是有害的.水泥的水化作用發(fā)生在有水分存在,而且氣溫在50F以上的條件下.為了保證水泥的水化作用得以進行,必須具備上述條件.如果干燥過快則會出現(xiàn)表面裂縫,這將有損于混凝土的強度,同時也會影響到水泥水化作用的充分進行.設計鋼筋混凝土構(gòu)件時顯然需要處理大量的參數(shù),諸如寬度.高度等幾何尺寸,配筋的面積,鋼筋的應變和混凝土的應變,鋼筋的應力等等.因此,在選擇混凝土截面時需要進行試算并作調(diào)整,根據(jù)施工現(xiàn)場條件.混凝土原材料的供應情況.業(yè)主對建筑和凈空高度的特殊要求.所用的設計規(guī)范以及建筑物周圍環(huán)境條件等最后確定截面.鋼筋混凝土通常是現(xiàn)場澆筑的合成材料,它與在工廠中制造的標準的鋼結(jié)構(gòu)梁.柱等不同,因此上述一系列因素必須予以考慮.對結(jié)構(gòu)體系的各個關(guān)鍵部位均需選定試算截面并進行驗算,以確定該截面的名義強度是否足以承受所作用的計算荷載.由于經(jīng)常需要進行多次試算,才能求出所需的截面,因此設計時第一次采用的數(shù)值將導致一系列的試算與調(diào)整工作.選擇混凝土截面時,采用試算與調(diào)整過程可以使復核與設計結(jié)合在一起.因此當試算截面選定后,每次設計都是對截面進行復核.手冊,圖表和微型計算機以及專用程序的使用,使這種設計方法更為簡捷有效,而傳統(tǒng)的方法則是把鋼筋混凝土的復核與單純的設計孤立地加以對待. 用于混凝土中的鋼筋 與混凝土相比,鋼是一種高強度材料。普通鋼筋在抗拉和抗壓時可以利用的強度，即屈服強度，約為普通的結(jié)構(gòu)混凝土抗壓強度的15倍，而且超過其抗拉強度的100倍。另一方面，與混凝土相比，鋼材的成本要高很多。所以，兩種材料最好的結(jié)合使用是，混凝土用于抵抗壓應力，縱向鋼筋配置在靠近受拉面處以抵抗拉應力，通常還附加配有一些鋼筋，抵抗梁內(nèi)剪力所引起的斜向拉應力。然而，鋼材也可以用于抵抗壓力，主要是為了減小受壓構(gòu)件的截面尺寸，例如用于多層建筑的下部樓層柱。即使不存在這種必要性，所有受壓構(gòu)件也要配置最少數(shù)量的鋼筋，以保證這些構(gòu)件在偶然出現(xiàn)的小彎矩作用下的安全性，在這情況下，不加鋼筋的混凝土構(gòu)件可能會開裂，甚至破壞。是配筋最有效地發(fā)揮作用的基本條件是鋼筋和混凝土的變形要一致，即這兩種材料間要有足夠強的粘結(jié)力，以確保鋼筋和其周圍混凝土間不發(fā)生相對移動。這種粘結(jié)力是由鋼筋混凝土結(jié)合面上較強的化學粘合作用、熱扎鋼筋表面層的固有粗糙度，以及間距較小的肋形表面變形等所構(gòu)成的。鋼筋的表面變形為兩種材料間提供了很高的咬合作用。使鋼筋和混凝土能夠很好地共同工作的其它特性有：1. 兩種材料的熱膨脹系數(shù)，鋼筋大約為6.510E-6，而混凝土的平均值為5.510E-6。這兩個數(shù)值相當接近，足以避免熱變形差值引起的混凝土開裂和其它不利影響。2. 裸露的鋼筋的抗腐蝕性很差，鋼筋周圍的混凝土為其提供了優(yōu)良的防腐蝕保護層，使腐蝕問題及相關(guān)的維護費用降至最低。3. 鋼材的熱傳導系數(shù)高，而且在高溫時其強度會大幅度下降，因而無防護層鋼筋的抗火性能較差。相反，混凝土的熱傳導系數(shù)相對較低。因此，即使長期暴露在火焰下，如果發(fā)生損壞的話，也僅僅限于混凝土的外層。厚度適當?shù)幕炷帘Ｗo層，可以為埋置在其內(nèi)的鋼筋提供充分的溫度絕緣。鋼材以兩種不同的方式應用于混凝土結(jié)構(gòu)中：普通鋼筋和預應力鋼筋。普通鋼筋在澆筑混凝土之前先置于模板內(nèi)。鋼筋中的應力，僅僅是由結(jié)構(gòu)上作用的荷載引起的。比較起來，在預應力混凝土結(jié)構(gòu)中，在鋼筋與混凝土共同工作承受外部荷載之前，對鋼筋已施加了很大的拉力。最常見的鋼筋（區(qū)別于預應力鋼筋）的形式為圓棒狀?，F(xiàn)在可以使用的鋼筋的直徑范圍很大，在一般的應用中從10至35mm，兩種大型鋼筋的尺寸為44和57mm。對這些鋼筋表面進行了處理，其目的是增加鋼筋與混凝土之間的抗滑能力。對這些變形（間距、凸起等）的最低要求已經(jīng)通過實驗研究予以確定。不同的鋼筋制造廠家采用不同的變形花紋，它們?nèi)慷寄軌驖M足這些要求。為了對鋼筋進行拼接，或者便于制做置于模板內(nèi)的鋼筋骨架所進行的焊接，可能會引起金相的變化而降低材料的強度和延性，因此，必須對所用鋼材的類型和焊接規(guī)程加以特殊的限制。ASTM中A706的條款是專門適用于焊接的。長期以來，在鋼筋混凝土的領(lǐng)域明顯地趨向于高強度材料，包括鋼筋忽然混凝土。屈服強度為40ksi（276MPa）的鋼筋，在20年前幾乎是標準的，目前大部分已由屈服強度為60ksi（414MPa）鋼筋所取代。因為后者更為經(jīng)濟，而且使用它們可以減少模板內(nèi)鋼筋的擁擠狀況。ACI規(guī)范允許使用強度fy=80ksi（552MPa）的鋼筋。這類高強鋼筋通常是逐漸屈服的，沒有屈服平臺。在這種情況下，ACI規(guī)范要求在規(guī)定的最小屈服強度時的總應變不超過0.0035。這是將現(xiàn)行的設計方法應用于這類高強鋼筋時所必須遵守的?，F(xiàn)行的設計方法是按鋼材突然屈服，而且有屈服平臺的情況而制訂的。ASTM規(guī)范中沒有關(guān)于屈服強度高于60ksi的變形鋼筋的條款但是在實際中可能使用這種鋼筋，根據(jù)ACI規(guī)范，它們可以在滿足上述要求的情況下使用。在特殊情況下，例如高層建筑的下部樓層的柱子，使用這一高強度范圍內(nèi)的鋼筋就非常適合。在惡劣的環(huán)境條件下，例如受除冰化劑侵蝕的橋面，要求使用鍍鋅或環(huán)氧樹脂涂層的鋼筋，以便使鋼筋的腐蝕和隨之發(fā)生的混凝土的剝落減至最小。Reinforced ConcretePlain concrete is formed from a hardened of cement, water, fine aggregate, coarse aggregate(crushed stone or gravel),air, and often other admixtures. The plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction of the cement/water mix, resulting in hardened concrete. The finished product has high compressive strength, and low resistance to tension ,such that its tensile strength is approximately one-tenth of its compressive strength. 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 element.It is this deviation in the composition of a reinforced concrete section from the homogeneity of standard wood or steel sections that requires a modified approach to the basic principles of structural design. The two components of the heterogeneous reinforced concrete section are to be so arranged and proportioned that optimal use is made of the materials involved. This is possible because concrete can easily be given any desired shape by placing and compacting the wet mixture of the constituent ingredients into suitable forms in which the plastic mass hardens. If the various ingredients are properly proportioned, the finished product becomes strong, durable, and, in combination with the reinforcing bars, adaptable for use as main members of any structural system.The techniques necessary for placing concrete depend on the type of member to be cast: that is, whether it is a column, a bean, a wall, a slab, a foundation, a mass concrete dam, or an extension of previously placed and hardened concrete. For beams, columns, and wall ,the forms should be well oiled after cleaning them ,and the reinforcement should be cleared of rust and other harmful materials In foundations, the earth should be compacted and thoroughly moistened to about 6 in .in depth to avoid absorption of the moisture present in the wet concrete .concrete should always be placed in horizontal layers which are compacted by means of high-frequency power-driven vibrators of either the immersion or external type, as the case requires unless it is placed by pumping .It must be kept in mind ,however ,that over-vibration can be harmful since it could cause segregation of the aggregate and bleeding of the concrete.Hydration of the cement takes place in the presence of moisture at temperatures above50F. It is necessary to maintain such a condition in order that the chemical hydration reaction can take place .If drying is too rapid ,surface cracking takes place .This would result in reduction of concrete strength due to cracking as well as the failure to attain full chemical hydration.It is clear that a large number of parameters have to be dealt with in proportioning a reinforced concrete element, such as geometrical width, depth, area of reinforcement, steel strain, concrete strain, steel stress, and so on .Consequently, trial and adjustment is necessary in the choice of concrete sections ,with assumptions based on conditions at site, availability of the constituent material, particular demands of the owners, architectural and headroom requirements, the applicable codes, and environmental conditions .Such an array of parameters has to be considered because of the fact that reinforced concrete is often a site-constructed composite, in contrast to the standard mill-fabricated beam and column sections in steel structures.A trial section has to be chosen for each critical location in a structural system. The trial section has to be analyzed to determine if its nominal resisting strength is adequate to carry the applied factored load. Since more than one trial is often necessary to carry at the required section, the first design input step generates into a series of trial-and-adjustment analyses.The trial-and-adjustment procedures for the choice of a concrete section lead to the convergence of analysis and design. Hence every design is an analysis once trial section is chosen. The availability of handbooks, charts, and personal computers and programs supports this approach as a more efficient, compact, and speedy instructional method compared with the traditional approach of treating the analysis of reinforced concrete separately from pure design. Reinforcing Steels for Concrete Compared with concrete, steel is a high strength material. The useful strength of ordinary reinforcing steels in tension as well as compression, i.e., the yield strength, is about 15 times the compressive strength of common structural concrete, and well over 100 times its tensile strength. On the other hand, steel is a high-cost material compared with concrete. It follows that the two materials are best used in combination if the concrete is made to resist the compressive stresses and the compressive force, longitudinal steel reinforcing bars are located close to the tension face to resist the tension force, and usually additional steel bars are so disposed that they resist the inclined tension stresses that are caused by the shear force in the beams. However, reinforcement is also used for resisting compressive forces primarily where it is desired to reduce the cross-sectional dimensions of compression members, as in the lower-floor columns of multistory buildings. Even if no such necessity exists, a minimum amount of reinforcement is placed in all compression members to safeguard them against the effects of small accidental bending moments that might crack and even fail an unreinforced member.For most effective reinforcing action, it is essential that steel and concrete deform together, i.e., that there be a sufficiently strong bond between the two materials to ensure that no relative movements of the steel bars and the surrounding concrete occur. This bond is provided by the relatively large chemical adhesion which develops at the steel-concrete interface, by the natural roughness of the mill scale of hot-rolled reinforcing bars, and by the closely spaced rib-shaped surface deformations with which reinforcing bars are furnished in order to provide a high degree of interlocking of the two materials.Additional features which make for the satisfactory joint performance of steel and concrete are the following:1. The thermal expansion coefficients of the two materials, about 0.0000065 for steel vs. an average of 0.0000055 for concrete, are sufficiently close to forestall cracking and other undesirable effects of differential thermal deformations.2. While the corrosion resistance of bare steel is poor, the concrete which surrounds the steel reinforcement provides excellent corrosion protection, minimizing corrosion problems and corresponding maintenance costs.3. The fire resistance of unprotected steel is impaired by its high thermal conductivity and by the fact that its strength decreases sizably at high temperatures. Conversely, the thermal conductivity of concrete is relatively low. Thus damage caused by even prolonged fire exposure, if any , is generally limited to the outer layer of concrete ,and a moderate amount of concrete cover provides sufficient thermal insulation for the embedded reinforcement.Steel is used in two different ways in concrete structures: as reinforcing steel and as prestressing steel. Reinforcing steel is placed in the forms prior to casting of the concrete. Stresses in the steel, as in the hardened concrete, are caused only by the loads on the structure, except for possible parasitic stresses from shrinkage or similar causes. In contrast, in prestressed concrete structures large tension forces are applied to the reinforcement prior to letting it act jointly with the concrete in resisting external loads.The most common type of reinforcing steel (as distinct from prestressing steel)is in the form of round bars, sometimes called rebars, available in a large range of diameters, from 10 to 35mm for ordinary application and in two heavy bar sizes of 44 and 57mm .These bars are furnished with surface deformations for the purpose of increasing resistance to slip between steel and concrete .Minimum requirements for these deformations(spacing, projection, etc. ) have been developed in experimental research. Different bar producers use different patterns, all of which satisfy these requirements.Welding of rebars in making splices, or for convenience in fabricating reinforcing cages for placement in the forms, may result in metallurgical changes that reduce both strength and ductility, and special restrictions must be placed both on the type of steel used and the welding procedures. The provisions of ASTM A706 relate specifically to welding.In reinforced concrete a long-time trend is evident the use of higher strength materials, both steel and concrete. Reinforcing bars with 40ksi (276MPa) yield stress, almost standard 20 years ago, have largely been replaced by bars with 60ksi (414MPa) yield stress, both because they are more economical and because their use tends to reduce congestion of steel in the forms.The ACI Code permits reinforcing steels up to fy=80ksi (552MPa). Such high strength steels usually yield gradually but have no yield plateau. In this situation the ACI Code requires that at the specified minimum yield strength the total strain shall not exceed 0.0035. This is necessary to make current design methods, which were developed for sharp-yielding steels with a yield plateau, applicable to such higher strength steels. There is no ASTM specification for deformed bars with yield stress above 60ksi, but such bars may be used, according to the ACI Code, providing they meet the requirements stated. Under special circumstances steel in this higher strength range has its place, e.g., in lower-story columns of high-rise buildings.In order to minimize corrosion of reinforcement and consequent spalling of concrete under severe exposure conditions such as in bridge decks subjected to deicing chemicals, galvanized or epoxy-coated rebars may be specified. 第 12 頁 共 12 頁