【摘要】：銹蝕是影響鋼結(jié)構(gòu)耐久性的重要影響因素之一。本文以工程中應(yīng)用廣泛的中等跨徑鋼箱梁橋?yàn)檠芯繉?duì)象,采用理論、試驗(yàn)與數(shù)值模擬相結(jié)合的方法,分析了點(diǎn)蝕影響下鋼梁受力特性,研究了點(diǎn)蝕對(duì)鋼箱梁腹板屈曲特性和極限承載力的影響。主要研究?jī)?nèi)容可以分為4個(gè)部分:(1)對(duì)3根均勻銹蝕和6根點(diǎn)蝕鋼梁分別進(jìn)行了靜力加載試驗(yàn)和有限元分析,研究了蝕坑的幾何尺寸(大小及深度)和分布對(duì)鋼梁承載力及破壞形態(tài)的影響。結(jié)果表明失重率是影響均勻銹蝕鋼材材料性能和鋼梁承載力的關(guān)鍵因素,但失重率不能全面衡量鋼梁的點(diǎn)蝕損傷程度;相同DOP條件下,蝕坑深度越大,極限承載力下降越明顯,銹蝕深度是影響點(diǎn)蝕鋼梁承載力的關(guān)鍵因素;點(diǎn)蝕鋼梁的極限承載力隨DOPV的增長(zhǎng)而下降,開孔(點(diǎn)蝕)腹板較未開孔腹板剛度下降明顯;當(dāng)DOPV達(dá)到一定程度時(shí),會(huì)使鋼梁腹板提前發(fā)生屈曲,這表明點(diǎn)蝕會(huì)影響鋼梁的失效形式。(2)對(duì)四邊簡(jiǎn)支邊界條件下點(diǎn)蝕鋼梁腹板的剪切屈曲荷載、剪切剛度及抗剪極限承載力進(jìn)行了研究。研究結(jié)果表明DOPA可以較好的描述點(diǎn)蝕影響下初始單板剪切剛度的變化趨勢(shì);DOPV可以較好的描述點(diǎn)蝕影響下剪切板彈塑性臨界荷載的變化趨勢(shì);并提出了點(diǎn)蝕影響下剪切板彈塑性臨界荷載的計(jì)算公式。(3)基于有限元計(jì)算結(jié)果對(duì)純剪切作用下工字梁腹板剪切屈曲的計(jì)算公式進(jìn)行了修正,并提出了鋼箱梁腹板剪切屈曲系數(shù)的計(jì)算公式。與有限元結(jié)果的相比表明,公式精度較高。對(duì)局部銹蝕條件下的鋼箱梁腹板進(jìn)行了有限元研究,研究發(fā)現(xiàn),銹蝕體積損失(DOPV)是影響局部銹蝕箱梁腹板的剪切屈曲強(qiáng)度的關(guān)鍵因素;并得出了基于綜合影響系數(shù)η的箱梁腹板剪切屈曲強(qiáng)度的計(jì)算公式,公式具有很好的適用性。(4)進(jìn)行了局部銹蝕影響下鋼箱梁抗剪極限承載力的試驗(yàn)研究與數(shù)值分析,得出了鋼箱梁抗剪極限承載力的建議公式。提出了描述點(diǎn)蝕程度的綜合影響系數(shù)?;基于綜合影響系數(shù)?得到了點(diǎn)蝕影響下鋼箱梁抗剪極限承載力的計(jì)算公式,該公式可以較為準(zhǔn)確的計(jì)算不同點(diǎn)蝕損傷程度下鋼箱梁的抗剪極限承載力。
[Abstract]:Corrosion is one of the important factors affecting the durability of steel structures. In this paper, the steel box girder bridge with medium span, which is widely used in engineering, is taken as the research object. The mechanical characteristics of the steel beam under the influence of pitting corrosion are analyzed by the method of combining theory, experiment and numerical simulation. The effect of pitting on the buckling characteristics and ultimate bearing capacity of steel box girder web was studied. The main research contents can be divided into four parts: (1) the static loading test and finite element analysis of three uniform corroded steel beams and six pitting steel beams are carried out. The influence of the geometric size (size and depth) and distribution of the pit on the bearing capacity and failure mode of the steel beam is studied. The results show that the weight loss rate is the key factor affecting the properties of uniformly corroded steel materials and the bearing capacity of steel beams, but the weight loss rate can not comprehensively measure the pitting damage degree of steel beams, and under the same DOP conditions, the greater the depth of corrosion pits, the more obvious the ultimate bearing capacity decreases. The corrosion depth is the key factor affecting the bearing capacity of pitting steel beams, the ultimate bearing capacity of pitting steel beams decreases with the increase of DOPV, and the stiffness of the perforated (pitting) web plate decreases significantly than that of the non-perforated web, and when the DOPV reaches a certain degree, The buckling of the steel beam web will occur in advance, which indicates that the pitting will affect the failure form of the steel beam. (2) the shear buckling load, shear stiffness and ultimate shear bearing capacity of the web plate of the pitting steel beam are studied under the condition of simply supported boundary. The results show that DOPA can well describe the change trend of shear stiffness of initial veneer under pitting corrosion, and DOPV can describe the change trend of critical load of shear plate under pitting effect. A formula for calculating the critical elastic-plastic load of shear plate under pitting corrosion is proposed. (3) based on the results of finite element method, the formula for calculating shear buckling of I-beam web plate under pure shear is modified. A formula for calculating the shear buckling coefficient of steel box girder web is presented. Compared with the finite element results, the formula has higher accuracy. The finite element analysis of the steel box girder web under the condition of local corrosion is carried out. It is found that the corrosion volume loss (DOPV) is the key factor affecting the shear buckling strength of the partially corroded box girder web. The formula for calculating the shear buckling strength of box girder web based on the comprehensive influence coefficient 畏 is obtained. The formula has good applicability. (4) the experimental study and numerical analysis of ultimate shear bearing capacity of steel box girder under the influence of local corrosion are carried out. The suggested formula of ultimate shear bearing capacity of steel box girder is obtained. The comprehensive influence coefficient which describes the pitting corrosion degree is put forward, which is based on the comprehensive influence coefficient? The formula for calculating the ultimate shear capacity of steel box girder under the influence of pitting corrosion is obtained. The formula can accurately calculate the ultimate shear capacity of steel box girder under different pitting damage degree.
【學(xué)位授予單位】：江蘇科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U448.213;U441

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