独塔地锚PC斜拉桥结构参数及体系研究

发布时间：2018-05-12 06:05

  本文选题：地锚斜拉桥 + 独塔半地锚PC斜拉桥　； 参考：《长安大学》2017年博士论文

【摘要】：本文针对独塔地锚预应力混凝土(PC)斜拉桥,以得到其适宜选取的体系及结构参数范围为目的展开了研究。介绍了研究对象的结构形式,论述了地形条件、施工工艺及主梁力学平衡机理,确定了适宜选取的体系。在此基础上建立了以安全要求为基础综合考虑经济性能及美观要求的结构性能评价体系,并据此展开了对独塔地锚PC斜拉桥关键结构参数合理范围的研究。所做的主要工作及主要成果包括:(1)通过对工程实例的调研,总结独塔地锚PC斜拉桥适应的地形条件为高低起伏的山区峡谷地形,适应的施工工艺为主跨悬臂浇筑施工,边跨悬臂浇筑或支架施工。(2)对不同斜拉桥体系进行恒活载内力计算,研究其力学平衡机理。结果表明:与常规斜拉桥相比,独塔地锚PC斜拉桥不对称性较高,结构受力特点为塔柱两侧拉索水平力差值较大,作用于主梁后需借助塔柱、承台或锚碇传递至基础,且塔柱所受弯矩较大;独塔半地锚PC斜拉桥的轴力平衡机理与跨中设伸缩铰的双塔半地锚斜拉桥相同,均需要锚碇所受的基底摩擦力及土侧压力平衡不对称结构极大的拉索水平力差值;但是,同为半地锚斜拉桥,双塔三跨锚碇与主梁分离的体系与独塔体系轴向受力截然不同,前者主跨塔梁结合处压力转化为跨中拉力,其所具备的减小塔梁交接处轴力以增大主跨跨度的优点并不适用于后者;独塔半地锚PC斜拉桥宜采用支撑体系,边跨主梁与锚碇宜固结;独塔全地锚PC斜拉桥宜采用固结体系且无下塔柱或采用截面面积较大的下塔柱。(3)论证了结构设计的造型适应性,提出了中小跨径独塔斜拉桥设计计算时需要考虑拉索承担的恒活载比例的观点,推导了体现结构整体刚度的活载作用下塔顶偏位及主跨最大挠度计算公式,构建了体现结构经济性的总造价及单位桥长造价估算方法,形成了以安全要求为基础综合考虑经济性能及造型需求的结构性能评价体系,为后续研究解决了研究方法问题。(4)以结构性能评价体系对独塔半地锚PC斜拉桥进行了研究,选定了边主跨比、锚碇边跨长度比、主跨边索倾角为关键结构参数,提出:(1)边主跨比的合理取值范围在0.25~0.50左右,跨度越大、锚固单价(锚碇锚杆承担荷载比)越高取值越大;当受地形条件限制仅考虑主跨跨越能力而边主跨比较小时,应适当降低主跨边索倾角增大地锚背索索距;当地形开阔考虑全桥跨越能力时,边主跨比宜取大值,且宜选择较大主跨边索倾角及较小锚碇边跨长度比;(2)当地形条件适宜采用独塔半地锚PC斜拉桥时,锚碇边跨长度比越大经济性能越高;(3)合理主跨边索倾角的取值在22.0°左右。研究表明了独塔半地锚PC斜拉桥在受地形条件限制仅考虑主跨跨越能力而边主跨比较小时经济性能优于常规斜拉桥。(5)以结构性能评价体系对独塔全地锚PC斜拉桥进行了研究,选定了塔柱倾角、地锚背索倾角、主跨边索倾角为关键结构参数,提出:(1)塔柱倾角的合理取值范围在65°~85°左右,且需满足最小塔柱倾角的要求;跨度越大、主跨边索倾角越大经济塔柱倾角取值越大,地锚背索倾角越大、锚固单价(锚碇锚杆承担荷载比)越大经济塔柱倾角取值越小;当地锚背索倾角取值合理时,经济塔柱倾角均大于根据受力及造型要求得到的最小塔柱倾角;(2)合理地锚背索倾角的取值在60°左右,在50°~70°之间;(3)合理主跨边索倾角的取值在22.5°左右,20.5°~25.0°之间,跨度越大、锚固单价越高取值越大。(6)分别对独塔半地锚及全地锚PC斜拉桥进行了试设计,并以此验证了活载作用下塔顶水平偏位、主跨最大挠度及材料用量的计算公式。
[Abstract]:In this paper, a single tower anchorage prestressed concrete (PC) cable-stayed bridge is studied in order to obtain the suitable selection system and the range of structural parameters. The structure form of the research object is introduced, the terrain conditions, the construction technology and the mechanism of the balance of the main beam mechanics are discussed, and the suitable selection system is determined. On this basis, the safety of the system is established. The structural performance evaluation system based on the comprehensive consideration of economic performance and aesthetic requirements is required, and the rational range of key structural parameters of the single tower anchor PC cable-stayed bridge is studied. The main work and main achievements are as follows: (1) through the investigation of the engineering examples, the topographic conditions of the Single Tower Anchorage PC cable-stayed bridge are summarized. Low undulating mountain canyon terrain, the suitable construction technology is mainly span cantilever pouring construction, Side Span Cantilever placement or scaffold construction. (2) calculation of constant live load of different cable-stayed bridge system, and study its mechanical balance mechanism. The results show that compared with conventional cable-stayed bridge, the Single Tower Anchorage PC cable-stayed bridge has higher asymmetry and structural stress characteristics The horizontal force difference between the two sides of the column is larger. After the effect on the main beam, the tower column, the bearing platform or the anchorage should be transferred to the foundation, and the bending moment of the column is larger. The axial force balance mechanism of the single tower and half anchor PC cable-stayed bridge is the same as that of the Twin Towers half anchorage bridge spanning the telescopic hinge in the middle of the bridge, all need the base friction and the earth pressure balance under the anchorage. The difference between the symmetrical structure and the horizontal force of the cable is great. However, the same as the half anchored cable-stayed bridge, the system of the three span anchorage of the Twin Towers is completely different from the single tower system, and the former is transformed into a mid span tensile force, and the advantages of reducing the axial force at the junction of the tower beam to increase the span of the main span are not applicable to the length of the main span. The latter, the single tower and half anchor PC cable-stayed bridge should adopt the support system, the side span of the main beam and the anchorage should be consolidated; the single tower full anchor PC cable-stayed bridge should adopt the consolidation system, without the lower column or the larger section of the lower section. (3) the adaptability of the structural design is demonstrated, and the design and calculation of the small span single tower cable-stayed bridge should be taken into consideration. In the view of the constant live load ratio, the calculation formula of the top deflection and the maximum deflection of the main span under the active load of the structure is derived, and the total cost of the structure economy and the cost estimation method of the unit bridge length are constructed, and the structural performance of the economic performance and the modeling demand is formed on the basis of the safety requirements. The evaluation system has solved the problem of research methods for the follow-up research. (4) study the single tower and half anchor PC cable-stayed bridge with the structural performance evaluation system, selected the side main span ratio, the span length ratio of the anchorage and the main span cable inclination angle as the key structural parameters, and put forward that the reasonable range of the main span ratio of (1) side is around, the greater the span, the larger the span, the anchorage single. The higher the value is, the higher the value is, the higher the value of the anchorage is bearing the load ratio; when the terrain conditions are limited to consider the span span of the main span and the side main span is relatively small, the anchor back cable distance should be appropriately reduced by the main span of the main span cable. When the terrain is open and the full bridge span capacity is considered, the side main span ratio should be taken large value, and the larger main span cable angle and the smaller angle should be selected. The span length ratio of the anchorage side; (2) when the topographic condition is suitable to adopt the single tower and half anchor PC cable-stayed bridge, the greater the economic performance of the span length ratio, and (3) the reasonable main span cable inclination angle is about 22 degrees. The study shows that the single tower and half anchorage cable stayed bridge is limited to the main span span and the side main span is relatively small on the terrain condition. The economic performance is better than the conventional cable-stayed bridge. (5) the single tower full anchor PC cable-stayed bridge is studied with the structural performance evaluation system. The column tilt angle, the ground anchorage angle and the main cross side cable inclination are the key structural parameters. (1) the reasonable range of the angle of the tower column is about 65 ~85 degrees, and the requirement of the minimum column inclination is met; the span is more than the span. The greater the angle of the economic tower, the greater the inclination angle of the economic tower, the greater the inclination angle of the economic tower, the greater the inclination angle of the anchor back cable, the smaller the inclination of the economic tower of the anchorage (anchorage anchor load ratio); the inclination of the economic tower column is greater than that of the minimum column angle according to the force and the requirement of the shape. (2) the reasonable anchor back. The value of the cable inclination is about 60 degrees, between 50 degrees ~70 degrees, and (3) the value of the reasonable main cross side cable inclination is about 22.5 degrees, 20.5 degrees ~25.0 degrees, the greater the span and the higher the value of the anchorage unit price. (6) the single tower and half anchor and the full anchor PC cable-stayed bridge are designed respectively, and the horizontal deviation of the top of the tower under the action of live load is verified, and the main span is the most main span. The formula for calculating the large deflection and the amount of material.

【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U448.27
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本文编号：1877422