【摘要】：在城市橋梁中單孔跨徑100m左右的小跨徑斜拉橋較為常見，然而一般的斜拉橋設計理論都是基于處于經(jīng)濟跨徑范圍的常規(guī)斜拉橋而得出的，，雖然其在力學計算上具有普遍性，但從結構利用效率的角度分析，一般性理論并不能很好地適用于小跨徑斜拉橋。索輔體系橋梁的出現(xiàn)使人們在設計小跨徑斜拉橋時有了新的選擇。通過充分利用小跨徑斜拉橋的主梁剛度，考慮主梁和拉索的組合受力，從而發(fā)揮其各自材料性能的設計理念，索輔體系橋梁能達到使用性和經(jīng)濟性的統(tǒng)一。鑒于目前鮮有專門針對索輔體系橋梁設計理論的系統(tǒng)性研究，本文對該體系的特征參數(shù)、設計關鍵問題、長期性能進行了詳細分析和評價。 首先，本文基于白山市向江大橋，對按常規(guī)斜拉橋理念設計的小跨徑斜拉橋的結構和受力特性進行了詳細分析；針對分析結果，從提高主梁剛度利用率和拉索強度利用率的角度，提出了小跨徑斜拉橋優(yōu)化設計方案，得到了索輔體系橋梁的體系特點；通過對該體系拉索恒載分擔率和疲勞強度容許應力的分析，提出以拉索恒載分擔率作為界定索輔體系橋梁的特征參數(shù)，并指出其取值范圍為35%~65%，同時拉索安全系數(shù)可取1.67~2.5。 然后，本文基于沈陽市三好橋對索輔體系橋梁設計過程中的關鍵問題進行了研究：推導了索輔體系橋梁主梁、拉索、橋塔等主要構件的剛度表達式，為定性掌握該體系整體剛度提供了依據(jù)；基于已得到的主梁和拉索剛度的計算式，采用比擬梁法推導了拉索活載分擔率表達式，分析了拉索活載分擔率與結構參數(shù)的關系，評價了該公式的計算精度，為掌握活載在結構中的分配提供了參考；闡述了主梁縱向預應力的設計方法，指出了采用彎起束提供豎向預應力的優(yōu)勢，分析了腹板束和頂?shù)装迨A應力效應的特點，為合理布束提供了借鑒；比較了簡支梁模型、梁格模型和實體模型計算拉索錨固橫隔梁的結果，評價了三種模型的適用性；分析了索輔體系橋梁內力和位移對不同結構參數(shù)的敏感性。 最后，本文簡要闡述了混凝土收縮和徐變的相關概念；通過建立按施工階段的有限元模型，分析了收縮徐變對索輔體系橋梁內力和位移的影響，評價了其長期性能；研究了混凝土加載齡期對該體系長期性能的影響，并指出了改善其長期性能的措施。
[Abstract]:Small span cable-stayed bridges with single span of 100 m or so are common in urban bridges. However, the general design theory of cable-stayed bridges is based on conventional cable-stayed bridges in the economic span range, although it is universal in mechanical calculation. However, from the point of view of structural utilization efficiency, the general theory is not suitable for small span cable-stayed bridges. The emergence of cable-assisted bridge makes people have a new choice in the design of small span cable-stayed bridge. By making full use of the stiffness of the main beam of the small span cable-stayed bridge and considering the combined force of the main beam and the cable, the design idea of their respective material performance can be brought into play. The cable-auxiliary system bridge can achieve the unity of usability and economy. In view of the lack of systematic research on bridge design theory of cable-auxiliary system at present, the characteristic parameters, key design problems and long-term performance of the system are analyzed and evaluated in detail in this paper. Firstly, based on Xiangjiang Bridge in Baishan City, the structure and mechanical characteristics of small span cable-stayed bridge designed according to the concept of conventional cable-stayed bridge are analyzed in detail. According to the analysis results, the optimum design scheme of small span cable-stayed bridge is put forward from the point of view of improving the utilization ratio of main girder stiffness and cable strength, and the system characteristics of cable-auxiliary system bridge are obtained. Based on the analysis of the tensile load sharing rate and the fatigue strength allowable stress of the system, the paper puts forward that the tension constant load sharing rate is used as the characteristic parameter to define the bridge of the cable auxiliary system, and points out that its value range is 35 / 65. At the same time, the cable safety factor may be 1.67 or 2.5. Then, based on the research of the key problems in the design process of the cable-auxiliary system bridge in Shenyang Sanhaoqiao, the stiffness expressions of the main girder, cable, tower and other main components of the cable-auxiliary system bridge are derived. It provides the basis for qualitatively mastering the overall stiffness of the system. Based on the calculated formula of stiffness of main beam and cable, the formula of live load sharing rate of cable is derived by analogy beam method, the relationship between live load sharing rate of cable and structural parameters is analyzed, and the calculation accuracy of the formula is evaluated. It provides a reference for mastering the distribution of live load in the structure. This paper expounds the design method of longitudinal prestress of main girder, points out the advantages of vertical prestressing force provided by bending beam, analyzes the characteristics of prestressing force effect of web beam and top and bottom slab, and provides a reference for rational distribution of beam. The results of simply supported beam model, girder lattice model and solid model are compared to evaluate the applicability of the three models, and the sensitivity of internal forces and displacements of cable-auxiliary system bridges to different structural parameters are analyzed. Finally, this paper briefly describes the concepts of shrinkage and creep of concrete, analyzes the influence of shrinkage and creep on the internal force and displacement of cable-auxiliary system bridge by establishing the finite element model of construction stage, and evaluates its long-term performance. The influence of concrete loading age on the long-term performance of the system is studied, and the measures to improve the long-term performance of the system are pointed out.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U448.27

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