【導(dǎo)讀】師的指導(dǎo)下進行的研究工作及取得的成果。盡我所知，除文中特別加。而使用過的材料。均已在文中作了明確的說明并表示了謝意。除了文中特別加以標(biāo)注引用的內(nèi)容外，本論文。不包含任何其他個人或集體已經(jīng)發(fā)表或撰寫的成果作品。究做出重要貢獻的個人和集體，均已在文中以明確方式標(biāo)明。全意識到本聲明的法律后果由本人承擔(dān)。同意學(xué)校保留并向國家有關(guān)部門或機構(gòu)送交論文的復(fù)印件和電子版，允許論文被查閱和借閱。本人授權(quán)大學(xué)可以將本學(xué)位。印或掃描等復(fù)制手段保存和匯編本學(xué)位論文。涉密論文按學(xué)校規(guī)定處理。近年來鋼結(jié)構(gòu)建筑在我國出現(xiàn)了非常快的發(fā)展勢頭，應(yīng)用范圍不斷擴。前我國的鋼結(jié)構(gòu)建筑所占比重還不到5%。的特點，在抗震設(shè)防烈度為7度及以下地區(qū)不需要考慮抗震設(shè)計。周期短且不需要大型的施工機具，因此本工程采用了門式剛架輕型房屋鋼結(jié)構(gòu)。進一步的將理論和實際相結(jié)合，對于今后的工作有著。一些國外的公司采用計算機輔助設(shè)計和計

　　

【正文】 kling considerations. The web must have sufficient thickness to resist buckling tendencies that are created by. girder curvature under load. As a girder deflects, a vertical pression is induced in the web due to the ponents of the flange stresses, the result of which constitutes a squeezing action. The buckling strength ofthe web must be capable of resisting this squeezing action. This is the basis for the ASDS criteria (Section G1) that the ratio of the clear distance between flanges to the web thickness must not exceed h/tw 14000/ )( ?yfyf FF ADSD EP.(G11) where h = clear distance between flanges tw = web thickness Fyf = specified minimum yield stress of the flange (ksi) It is allowed for this ratio to be exceeded if transverse intermediate stiffeners are provided with a spacing not in excess of times the distance between flanges. The maximum permissible 0 ratio then bees maximum h/ tw =20xx/ yfF ASDS EP.(G12) 浙江大學(xué)城市學(xué)院畢業(yè)設(shè)計 參考文獻 TABLE54 Maximum h/ tw Rations h/tw Fyf 36ksi 42ksi 46ksi 50ksi 14000/ )( ?yfyf FF 20xx/yfF 322 282 261 243 333 309 295 283 Resulting values for the preceding two expressions, as functions of various F yf values, are shown in Table 54. In addition, web buckling considerations may require a reduction of the allowable bending stress in the pression flange. According to the ASDS, Section G2, when the web depththickness ratio exceeds 760/ bF , the maximum bending stress in the pression flange must be reduced to a value that may be puted from ASDS Equation (G2l). Plate girder webs that depend on tension field action (to be defined shortly), as discussed in ASDS. Section G3, must be proportioned so that the web bending tensile stress due to moment in the plane of the web does not exceed y or （ /Fv ） Fy ASDS Ep(G51) where fv =puted average web shear stress (total shear divided by web area) (ksi) Fv =allowable web shear stress according to ASDS Equation (G3l) (ksi) 浙江大學(xué)城市學(xué)院畢業(yè)設(shè)計 參考文獻 This expression in effect constitutes an allowable bending stress reduction due to the interaction of concurrent bending and shear stress (ASDS, Section G5). After preliminary web dimensions are selected, the required flange area may be determined by using an approximate approach as follows. With reference to Figure 521, the moment of inertia of the total section with respect to axis xx is Ix =Ix(web) +I(flanges) Neglecting the moment of inertia of the flange areas about their own centroidal axes and assuming that h=(dt f ),an approximate gross moment of inertia may be expressed as Ix = tw h3 /12+2Af (h/2) 2 Expressing this in terms of the section modulus (S) and also assuming that h? d: Sx = tw h3 /12/h/2+2Af (h/2)2 /h/2 = tw h2 /6+Af h 浙江大學(xué)城市學(xué)院畢業(yè)設(shè)計 參考文獻 FIGURE 521 Girder nomenclature. The required Sx = M/Fb 。 therefore, M/Fb =tw h2 /6+Af h and required Af =M/Fb htw h/6 where Af = area of one girder flange h = depth of the girder web Fb = allowable bending stress for the pression flange 浙江大學(xué)城市學(xué)院畢業(yè)設(shè)計 參考文獻 M= maximum bending moment with respect to xx axis The first portion of this expression M/(F b h) represents the required flange area necessary to resist the bending moment M, assuming no contribution by the girder web. Since the web does furnish some bending moment resistance, however, the second term (tw h/6) is included. Based on the puted required flange area, actual proportions of the flange can be determined by taking into account additional ASDS criteria. To prevent a localized buckling of the pression flange, the ASDS, Section B5 and Table , places an upper limit on the widththickness ratio of the flange. This upper limit for the flange of an Ishaped plate girder is that tabulated for a nonpact shape in Table . The nonpact classification is used, since it is not likely that girder dimensions will be such that a pact section is produced. Therefore, in general, the maximum allowable bending stress is taken as y . For the flange to be considered fully effective (not subject to further allowable stress reductions), the widththickness ratio of the pression flange may not exceed cx kF/ . This may be expressed mathematically as b/t? 95/ cx kF/ where b= half the full nominal flange width (t//z) t= the flange thickness (tf ) Fy =the specified minimum yield stress (ksi) (for a hybrid girder, use the yield strength of the flange Fyf instead of Fy ) 浙江大學(xué)城市學(xué)院畢業(yè)設(shè)計 參考文獻 kc = a pressive element restraint coefficient If h/t70, kc is determined from Kc =（ h/t） Otherwise, kc is taken as . h is defined as the clear distance between flanges. Values of cy kF / are tabulated in Table 5 of the Numerical Values section of the ASDS for the case where k c =. For A36 steel the maximum flange plate width (for a fully effective flange) is determined from b/t=bf /2tf from which maximum bf =2（ tf ） = tf As was mentioned previously, a reduction of the allowable bending stress in the pression flange due to web buckling will be necessary if the web depththickness ratio exceeds 760/ bF . When this occurs, the allowable flange stress may not exceed Fb ’? Fb [(h/tw 760/ bF )] Re ASDS Ep(G21) Modified wher