【正文】 Limit State Design of Brickwork The basic aim of structural design is to ensure that a structure should fulfill its intended function throughout its lifetime without excessive deflection, cracking or collapse, and this aim must of course be met with due regard to designer is assisted in his task by the availability of a code of practice which is based on accumulated experience and research. Up to the present time, such codes have sought to ensure the safety and serviceability of masonry structures by specifying permissible stresses for various types and binations of materials. Thus codes generally give basic pressive stresses for a range of brickmortar binations。這種在彈性理論 中固有的假設(shè)和普通鋼筋混凝土中的假設(shè)十分相似。在實(shí)際工作，必須采用簡(jiǎn)化和理想化的曲線。但上面的混凝土板有和鋼梁上下分離的趨勢(shì)，這樣就不能傳遞水平剪力 .超載或振動(dòng)荷載引起的疲勞作用將破壞混凝土板與鋼梁間的天然粘結(jié)九這種粘結(jié)力一旦遭到破壞就不可恢復(fù)。 在任何一種 機(jī)械式連接體系中，它可以使傳遞水平剪力和避免使板和梁分開這兩個(gè)作用統(tǒng)一在一起。 近年來，通過考慮相應(yīng)的“極限狀態(tài)”，即結(jié)構(gòu)或其一部分達(dá)到一種不鴿完成其功能的狀態(tài)或結(jié)構(gòu)不再滿足設(shè)計(jì)規(guī)定條件的狀態(tài)，形成了一種解決結(jié)構(gòu)安全性和適用性的更合理的設(shè)計(jì)方法。 材料的特征強(qiáng)度通常根據(jù)相應(yīng)的試驗(yàn)結(jié)界取為具有 95%保證率的值。理想情況是荷載和強(qiáng)度應(yīng)該由數(shù)理統(tǒng)計(jì)方法給出，但實(shí)際上這幾乎是不可能的，因此其特征值只得根據(jù)一些手頭資料確定 .對(duì)荷載而言，這些資料通常來源于對(duì)使用中的建筑物進(jìn)行觀測(cè)，但對(duì)材料的特征強(qiáng)度而言，是根據(jù)試驗(yàn)結(jié)果得出的，試驗(yàn)結(jié)果有時(shí)會(huì)成為特征強(qiáng)度數(shù)理統(tǒng)計(jì)的依據(jù)。該系數(shù)也是以下兩分項(xiàng)系數(shù)的函數(shù)。 在結(jié)構(gòu)的使用期間，特征荷載的取值通常具有 5%的失效概率，但在多種情況下，由于統(tǒng)計(jì)資料不足，在實(shí)用規(guī)范或其他規(guī)程中，只給出其名義值。 設(shè)計(jì)者在其工作中可借助于靠積累的經(jīng)驗(yàn)和科研成果形成的現(xiàn)行規(guī)范。 抗剪連接鍵的研究發(fā)展比較緩慢，它需廣泛地對(duì)大量機(jī)械式連接鍵進(jìn)行靜力和疲勞試驗(yàn)。在普通鋼筋混凝土構(gòu)建中雖然有時(shí)確有需要附加錨固的情況，但混凝土與鋼筋間的天然粘結(jié)力足以起到這種作用。 清楚地了解組合梁中各部件：鋼梁、混凝土板及剪力連接鍵對(duì)外荷載作用的反應(yīng)是透徹分析組合截面的基礎(chǔ)。以此來提供既經(jīng)濟(jì)又安全的設(shè)計(jì)準(zhǔn)則。failure stresses (yield in the case of steel, crushing in the case of concrete). The assumptions inherent in the elastic method are similar to those for ordinary reinforced concrete. In recent39。 years the concepts of the ultimate load design philosophy have been applied to posite action and a body of experimental evidence has shown it to be a safe, economical basis on which to proportion posite sections. Although at the present time ultimate load design methods are directly applicable only to buildings and not to bridges there seems no reason to doubt that in time the restriction will disappear. Before dealing in detail with the two design approaches (elastic and ultimate load) basic points require consideration. A clear understanding of the way in which the ponent materials, steel concrete and shear connection react to applied load is an essential preliminary to full analysis of the posite section. Of primary importance are the stress strains relationships, which must of necessity be the product of carefully controlled experiment. These experimental results are not generally suited to direct application and so simplifications and idealisations are adopted in practice. The use of puters has made it possible to reduce the amount of idealisation required with the result that puter `experiments39。這一樣的主要目的是詳細(xì)介紹一些在組合結(jié)構(gòu)設(shè)計(jì)中必須考慮的重要基本概念。其中最重要的是應(yīng)力應(yīng)變關(guān)系曲線。完全埋置在混凝土內(nèi)的現(xiàn)澆肋梁有著較大的錨固面積，這足能傳遞剪力，然而，這完全不同于普通組合梁。 早期的研究者很快就清楚地發(fā)現(xiàn) :有必要把某種連接鍵一端固定于鋼梁的上翼緣之上，另一端錨人混凝土板中。到目前為止，這些規(guī)范通過規(guī)定各種材料及其組合體的允許應(yīng)力來摸索保證砌體結(jié)構(gòu)的安全性和適用性 .因而，規(guī)范一般給出磚和砂漿 組合范圍內(nèi)的基本抗壓應(yīng)力，在特定情況下基本應(yīng)力再根據(jù)砌體的長(zhǎng)細(xì)比和荷載的偏心程度予以調(diào)整。 f? 是一系列分項(xiàng)系數(shù)的函數(shù)。 1c? 用以考慮結(jié)構(gòu)的特征和性能，例如結(jié)構(gòu)或結(jié)構(gòu)的一部分在沒有預(yù)兆時(shí)可能全部或部分倒塌，這種情況下不可能發(fā)生內(nèi)力重分布，或者說單個(gè)構(gòu)件