本文選題：反演理論　切入點(diǎn)：預(yù)應(yīng)力　出處：《長(zhǎng)安大學(xué)》2015年博士論文

【摘要】：隨著我國(guó)交通事業(yè)的快速發(fā)展,大跨徑預(yù)應(yīng)力混凝土箱梁橋被廣泛應(yīng)用于鐵路、公路橋上。此類橋型在運(yùn)營(yíng)過(guò)程中,有相當(dāng)數(shù)量的出現(xiàn)了不同程度的開(kāi)裂、下?lián)系葥p傷問(wèn)題,且日益突出,已直接影響到結(jié)構(gòu)的安全性、使用性及耐久性。本文主要針對(duì)大跨徑預(yù)應(yīng)力混凝土梁橋服役期間梁體抗彎剛度退化程度、有效預(yù)應(yīng)力的真實(shí)狀態(tài)進(jìn)行了研究,提出了以反演理論為基礎(chǔ),通過(guò)建立參數(shù)反演分析程序,根據(jù)預(yù)應(yīng)力混凝土梁橋運(yùn)營(yíng)期間不同時(shí)間點(diǎn)控制截面實(shí)測(cè)撓度值,對(duì)梁體抗彎剛度損傷及頂板、邊跨底板及中跨底板有效預(yù)應(yīng)力進(jìn)行了反演識(shí)別的分析方法。通過(guò)分析發(fā)現(xiàn),隨著服役時(shí)間的不斷延長(zhǎng),梁體損傷日益嚴(yán)重,抗彎剛度不斷退化。同時(shí),梁體有效預(yù)應(yīng)力也隨時(shí)間不斷減小,其中,頂板縱向有效預(yù)應(yīng)力最大,邊跨底板縱向有效預(yù)應(yīng)力次之,中跨底板縱向有效預(yù)應(yīng)力降低程度最小。以在役預(yù)應(yīng)力混凝土梁橋裂縫調(diào)查數(shù)據(jù)為基礎(chǔ),根據(jù)統(tǒng)計(jì)學(xué)原理,建立了正裂縫、斜裂縫特征統(tǒng)計(jì)參數(shù)。分別分析了正裂縫、考斜裂縫及正、斜裂縫共同作用三種情況對(duì)梁體撓度的影響規(guī)律。由分析可知,正裂縫、斜裂縫均會(huì)對(duì)梁體下?lián)袭a(chǎn)生影響,其中,正裂縫對(duì)其梁體撓度影響較大,斜裂縫對(duì)其影響很小。分別分析了正裂縫、斜裂縫及正、斜裂縫共同作用三種情況對(duì)梁體截面上緣應(yīng)力、下緣應(yīng)力及腹板主應(yīng)力的影響規(guī)律。由分析可知,正裂縫對(duì)墩頂截面上緣應(yīng)力影響較小,對(duì)邊跨跨中截面、中跨跨中截面上緣應(yīng)力影響較大;斜裂縫對(duì)邊跨跨中、中跨跨中截面上緣應(yīng)力影響較小,對(duì)墩頂截面上緣應(yīng)力影響較大。正裂縫對(duì)邊跨跨中截面、中跨跨中截面下緣應(yīng)力影響較大,對(duì)墩頂截面下緣應(yīng)力影響較小;斜裂縫對(duì)邊跨跨中截面、墩頂截面及中跨跨中截面下緣應(yīng)力影響均較小。正裂縫對(duì)梁體各截面腹板主拉應(yīng)力影響較小,斜裂縫對(duì)梁體各截面腹板主拉應(yīng)力影響較大。根據(jù)鋼筋與混凝土相對(duì)應(yīng)變關(guān)系,推導(dǎo)了梁體平均裂縫寬度計(jì)算公式,通過(guò)逐級(jí)加載,分析了梁體控制截面區(qū)域正截面平均裂縫寬度的變化規(guī)律。
[Abstract]:With the rapid development of transportation in China, long-span prestressed concrete box girder bridges are widely used in railway and highway bridges. And it is becoming more and more prominent, which has directly affected the safety, serviceability and durability of the structure. In this paper, the true state of the effective prestress and the degradation degree of the flexural stiffness of the beam during the service period of the long-span prestressed concrete beam bridge are studied in this paper. Based on the inversion theory, a program for parameter inversion analysis is established. According to the measured deflection values of the section at different time points during the operation of prestressed concrete beam bridge, the flexural stiffness damage and roof damage of prestressed concrete beam bridge are proposed. The effective prestressing force of side span floor slab and middle span floor slab are analyzed by inverse identification. It is found that with the continuous extension of service time, the damage of beam body becomes more and more serious, and the bending stiffness is continuously degraded. The effective prestress of beam body also decreases with time. Among them, the longitudinal effective prestress of roof slab is the largest, and the longitudinal effective prestressing force of side span slab is the second. Based on the investigation data of cracks of existing prestressed concrete beam bridge, the statistical parameters of normal cracks and oblique cracks are established based on the investigation data of in-service prestressed concrete beam bridges. The influence of oblique crack, positive crack and oblique crack on the deflection of beam body is studied. From the analysis, it can be seen that the positive crack and oblique crack have an effect on the deflection of beam body, among which, the positive crack has a great effect on the deflection of beam body. The influence of oblique crack on the upper edge stress, lower edge stress and principal stress of web plate of beam is analyzed respectively in three situations: normal crack, oblique crack and positive crack, oblique crack and oblique crack. The influence of normal crack on the upper edge stress of pier top section is small, and on the middle cross section of side span and middle span section is greater, while the effect of oblique crack on the upper edge stress of middle span and middle span is smaller than that of oblique crack. The effect on the upper edge stress of the pier top section is greater. The middle edge stress of the middle span section and the middle span section have a greater effect on the middle edge stress of the pier top section, and the oblique crack has a little effect on the lower edge stress of the pier top cross section, while the oblique crack has a great effect on the middle section of the side span. The influence of normal crack on main tensile stress of web plate of beam body is small, and oblique crack on main tensile stress of web plate of beam body. According to the relative strain relationship between steel bar and concrete, the influence of pier top section and middle span middle span on the lower edge stress of web section of beam body is small, and the influence of oblique crack on the main tensile stress of each section web plate of beam body is greater. The formula for calculating the average crack width of beam body is derived, and the variation law of average crack width of normal section in the region controlled by beam body is analyzed by step by step loading.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U441.4

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