【正文】
筑物破壞而造成的物質(zhì)和材料損失費(fèi); ( 4)在社會(huì)上造成的不良影響; ( 5)精神和心理上的考 慮。第一種方法對(duì)材料和荷載采用不同的安全系數(shù),而不需要采用概率準(zhǔn)則;第二種方法是引入一些而簡(jiǎn)化假設(shè)的近似概率方法(半概率方法)。概率法取決于: ( 1)制作和安裝過程中材料強(qiáng)度的隨機(jī)分布(整個(gè)結(jié)構(gòu)的力學(xué)性能數(shù)值的分散性); ( 2)截面和結(jié)構(gòu)幾何尺寸的不確定性(由結(jié)構(gòu)制作和安裝造成的誤差和缺陷而引起的); 對(duì)作用在結(jié)構(gòu)上 的活載和恒載的預(yù)測(cè)的不確定性; 所采用的近似計(jì)算方法有關(guān)的不精確性(實(shí)際應(yīng)力與計(jì)算應(yīng)力的偏差)。 ( 2)極限狀態(tài)法,在這種方法中,結(jié)構(gòu)的工作狀態(tài)是以其最大強(qiáng)度為依據(jù)來衡量的。 破壞不僅僅指結(jié)構(gòu)的整體破壞,而且還指結(jié)構(gòu)不能正常的使用,或者,用更為確切的話來說,把破壞看成是結(jié)構(gòu)已經(jīng)達(dá)到不能繼續(xù)承擔(dān)其設(shè)計(jì) 荷載的 “極限狀態(tài) ”。特殊型式的翻斗車包括容量為 4 m179。一旦鏟運(yùn)機(jī)裝滿,助推拖拉機(jī)就回到開挖的地點(diǎn)去幫助下一臺(tái)鏟運(yùn)機(jī)。卸都不準(zhǔn)確。它將幫助他在最短的時(shí)間內(nèi)獲得最好的方案。那是大部分土方是采用窄軌鐵路運(yùn)輸,在這目前來說是很少采用的。鋼筋混凝土通常是現(xiàn)場(chǎng)澆注的合成材料,它與在工廠中制造的標(biāo)準(zhǔn)的鋼結(jié)構(gòu)梁、柱等不同,因此對(duì)于上面所提到的一系列因素必須予以考慮。一般情況下,除使用混凝土泵澆筑外,混凝土都應(yīng)在水平方向分層澆筑,并使用插入式或表 面式高頻電動(dòng)振搗器搗實(shí)。 由于鋼筋混凝土截面在均質(zhì)性上與標(biāo)準(zhǔn)的木材或鋼的截面存在著差異,因此,需要對(duì)結(jié)構(gòu)設(shè)計(jì)的基本原理進(jìn)行修改。 (3) Cost of physical and material damage due to the failure of the construction。 and corrosion. Computational methods used to verify structures with respect to the different safety conditions can be separated into: (1)Deterministic methods, in which the main parameters are considered as nonrandom parameters. (2)Probabilistic methods, in which the main parameters are considered as random parameters. Alternatively, with respect to the different use of factors of safety, putational methods can be separated into: (1)Allowable stress method, in which the stresses puted under maximum loads are pared with the strength of the material reduced by given safety factors. (2)Limit states method, in which the structure may be proportioned on the basis of its maximum strength. This strength, as determined by rational analysis, shall not be less than that required to support a factored load equal to the sum of the factored live load and dead load ( ultimate state ). The stresses corresponding to working ( service ) conditions with unfactored live and dead loads are pared with prescribed values ( service limit state ) . 6 From the four possible binations of the first two and second two methods, we can obtain some useful putational methods. Generally, two binations prevail: (1)deterministic methods, which make use of allowable stresses. (2)Probabilistic methods, which make use of limit states. The main advantage of probabilistic approaches is that, at least in theory, it is possible to scientifically take into account all random factors of safety, which are then bined to define the safety factor. probabilistic approaches depend upon : (1) Random distribution of strength of materials with respect to the conditions of fabrication and erection ( scatter of the values of mechanical properties through out the structure )。 and the articulated type of about m 179。1 2 外文翻譯 Introduction to reinforced concrete and earth works Abstract: As a designer must first clear the building structure itself was designed and intensity levels, as well as related issues indepth discussion and research, this paper describes on the reinforced concrete, earthwork engineering knowledge, let more indepth understanding of this Discusses the key, and the rational application of knowledge to help us design more excellent building Keywords: concrete, earthwork, structural safety 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 admixtures. 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 concrete. The finished product has high pressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its pressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to pensate for the weak tension regions in the reinforced concrete element. It is this deviation in the position of a reinforces 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 ponents of the het