行车道板计算及参考文献.doc

10 行车道板计算考虑到主梁翼缘板内配筋是连续的，故行车道板可按悬臂板（边梁）和两端固结的连续板（中梁）两种情况来计算。10.1 悬臂板荷载效应计算由于横隔梁宽跨比大于2，故悬臂板可按单向板计算6，悬臂长度为1.15m，计算时取悬臂板宽度为1.0 m。10.1.1 永久作用（1）主梁架设完毕时桥面板可看成80cm长的单向悬臂板，计算图式见图10-1 b。计算悬臂根部一期永久作用效应为：弯矩：(kNm)剪力： (kNm)（2）成桥后桥面现浇部分完成后，施工二期永久作用，此桥面板可看成跨径为0.9m的悬臂单向板，计算图式如图10-1c、d所示。图中：g10.121253.0（kN/m）,为现浇部分自重；P1.5kN，为防撞栏重力。计算二期永久作用效应如下：弯矩：=1.643(kNm)剪力：Vg23.00.20+1.5=2.1(kN)（3）总永久作用效应综上所述，悬臂根部永久作用效应为：弯矩：Mg0.8981.6432.541(kNm)剪力：Vg=3.52.15.6(kN)图10-1 悬臂版计算图式（尺寸单位：mm）10.1.2 可变作用在边梁悬臂版处，只作用有人群，计算图式为10-1d弯矩：Mr0.74(kNm)剪力：Vr=3.50.652.275(kN)10.1.3 承载能力极限状态作用基本组合按桥规4.1.6条：Md 1.2Mg+1.40.8Mr（1.22.541+1.40.80.74）3.878(kNm)Vd1.2Vg+1.40.8Vr1.25.6+1.40.82.275=9.268(kN)10.2 连续板荷载效应计算对于梁肋间的行车道板，在桥面现浇部分完成后，行车道板实质上是一个支承在一系列弹性支承上的多跨连续板，实际受力很复杂。目前，通常采用较简便的近似方法进行计算。对于弯矩，先计算出一个跨度相同的简支板在永久作用和活载作用下的跨中弯矩M0，再乘以偏安全的经验系数加以修正，以求得支点处和跨中截面的设计弯矩。弯矩修正系数可视板厚t与梁肋高度h的比值来选用。本设计，即主梁抗扭能力较大，取跨中弯矩：Mc0.5M0 ；支点弯矩Ms0.7 M0。对于剪力，下面分别计算连续板的跨中和支点作用效应值。10.2.1 永久作用（1）主梁架设完毕时桥面板可看成80cm长的悬臂单向板，计算图式见图10-1b，其根部一期永久作用效应为：弯矩：Mg10.898(kNm)剪力：Vg13.5(kN)（2）成桥后：先计算简支板的跨中弯矩和支点剪力值。根据公预规4.1.2条，梁肋间的板，其计算跨径按下列规定取用：计算弯矩时，ll0t，但不大于ll0b；本例l1.80.121.92(m)计算剪力时，ll0；本例l1.8m。式中：l板的计算跨径；l0板的净跨径；t 板的厚度；b 梁肋宽度。计算图式见图10-2。图10-2中：g13.0kN/m，为现浇部分桥面板的自重；g2（0.02+0.113）1/2125+0.051232.8125kN/m，是二期永久作用，包括混凝土垫层和沥青面层。计算得到简支板跨中二期永久作用弯矩及支点二期永久作用剪力为：Mg2（0.380.48）0.203.00.51.920.482.81251.812(kNm)Vg20.203.00.92.81253.13(kN)图10-2 简支板二期永久作用计算图式（尺寸单位：mm）（3）总永久作用效应综上所述,支点断面永久作用弯矩为：Msg0.8980.71.8122.166(kNm)； 支点断面永久作用剪力为：Vsg3.53.136.63(kN)； 跨中断面永久作用弯矩为：Mcg0.51.8120.906(kNm)10.2.2 可变作用根据桥规4.3.1条，桥梁结构局部加载时，汽车荷载采用车辆荷载根据桥规4.3.1-2，后轮着地宽度b1及长度a1为：a10.25m，b10.6m平行于板的跨径方向的荷载分布宽度：bb12h0.620.130.86(m)（1）车轮在板的跨径中部时垂直于板的跨径方向的荷载分布宽度：,取a1.28m，此时两个后轮的有效分布宽度发生重叠，应求两个车轮荷载的有效分布宽度a1.281.22.48(m)，折合成一个荷载的有效分布宽度a2.48/21.24(m)。（2）车轮在板的跨径方向荷载的有效分布宽度：aa12ht0.2520.130.120.63m（1） 车轮在板的支承附近，距支点距离为x时垂直于板的跨径方向荷载的有效分布宽度：aa12ht2x0.632x(m)a的分布见图10-3。 图10-3 简支板可变作用（汽车）计算图式（尺寸单位：mm）将加重车后轮作用于板的中央，求得简支板跨中最大可变作用（汽车）的弯矩为： (kNm)计算支点剪力时，可变作用必须尽量靠近梁肋边缘布置。考虑了相应的有效工作宽度后，每米板宽承受的分布荷载如图10-3所示，支点剪力Vsp的计算公式为：Vsp（1）（A1y1A2y2A3y3A4y4）其中：代入上式，得到Vsp1.3(56.450.76119.690.943548.570.20569.690.0565)=62.64(kN)综上所述，可得到连续板可变作用（汽车）效应如下：支点断面弯矩：M sp0.727.3419.14(kNm)支点断面剪力：Vsp62.64(kN)；跨中断面弯矩：Mcp0.527.3413.67(kNm)。10.2.3 作用效应组合按桥规4.1.6条进行承载能力极限状态作用效应基本组合。支点断面弯矩：1.2Msp1.4 Msg 1.22.1661.419.14=29.4(kNm)支点断面剪力：1.2Vsg1.4Vsp1.26.631.462.6495.65 (kN)；跨中断面弯：1.2Mcg1.4Mcp1.20.9061.413.6720.23(kNm)。10.3 截面设计、配筋与承载力验算悬臂板及连续板支点采用相同的抗弯钢筋，故只需要按其最不利荷载效应配筋，即Md29.4kNm。其高度为h20cm，净保护层a3cm。若选用12钢筋，则有效高度为：按公桥规5.2.2条：1.029.422.4103x(0.163x/2)x0.0083(m)验算：bh00.400.1630.0652(m)x0.0083(m)按公桥规5.2.2 条：查有关板宽1m内钢筋截面与距离表，当选用12钢筋时，需要钢筋间距为17，此时所提供的钢筋面积为：As6.65cm26.64cm2。由于此处钢筋保护层与试算值相同，实际配筋面积又大于计算面积，则其承载力肯定大于作用效应，故承载力验算可从略。 kNm,解得：x=0.0056As=所以，连续板跨中截面处需在板的下缘配置钢筋间距为24cm的12钢筋。为使施工简便，取板上下缘配筋相同，均为12170mm。配筋布置如图10-4。按公桥规5.2.9 条规定，矩形截面受弯构件的截面尺寸要符合下列要求。即： 满足抗截最小尺寸要求。按公桥规5.2.10 条，即：0.5010-31.251.831000163=186.43kN时，不需要进行斜截面抗剪强度计算，仅按构造要求配置钢筋。图10-4 行车道板受力钢筋布置图式（尺寸单位：mm）根据公桥规9.2.5条，板内应设置垂直于主钢筋的分布钢筋，直径不应小于8mm，间距不应大于200mm，因此本例中板内分布钢筋用8150mm。参考文献1公路工程技术标准（JTG B01-2003）北京：人民交通出版社，20032公路桥涵设计通用规范（JTG D60-2004）北京：人民交通出版社，20053公路钢筋混凝土及预应力混凝土桥涵设计规范（JTG D62-2004）北京：人民交通出版社，20044城市桥梁设计荷载标准（CJJ77-98）北京：人民交通出版社，19985公路桥涵地基与基础设计规范（JTJ063-2007）北京：人民交通出版社，20076桥梁工程主编：邵旭东北京：人民交通出版社，20077结构设计原理主编：叶见曙北京：人民交通出版社，20058基础工程主编：王小谋北京：人民交通出版社，20049城市桥梁工程主编：张明君等北京：中国建筑工业出版社，200010桥梁预应力混凝土技术及设计原理主编：李国平北京：人民交通出版社，200211桥梁设计百问（第二版）主编：邵旭东、胡建华北京：人民交通出版社，200512桥梁设计与计算主编：邵旭东、程翔云、李立峰北京：人民交通出版社，2007附录THE MAIN PROBLEMS OFDOMESTIC BRIDGE DESIGNINGNow, the countrys structural design process, such tendencies: more intensity considered in the design and durability consider less attention intensity limit to the use of state without limit state, and throughout the life cycle of the most important when it is precisely the use of performance; attention to the construction of the structure without attention to the maintenance of the structure. In fact, the current design of the bridge for more durability is a concern, as a concept, did not explicitly put forward the request of the use of life, nor the durability of specialized design. These tendencies to a certain extent, led to the current project accidents, the use of poor performance, the short life of the adverse consequences of structural engineering with the increasing emphasis on international durability, safety, contrary to the trend of applicability; does not conform to the structure dynamic and comprehensive economy requirements.Bridge safety, durability, the main reason for poor 1) Construction and management of low level More bridges at home and abroad destruction and the sudden collapse of the bridge has been engineering more concerned about security issues. The general view is that the current project is barbaric incident management and construction caused by corruption. For the short term, such as the destruction and collapse of a sudden, mostly because of construction quality did not meet specifications and design requirements, typical problems include inadequate and construction materials intensity of failure; also exist, such as individual bridge jerry serious management issues, but also on bridge safety of the fatal damage.And a large number of bridges in the far did not achieve the expected life time, there has been affecting the normal use of disease and deterioration, especially in a number of bridges in use only a few years, or even just completed soon on the serious problem of insufficient durability, which and the low quality of construction is an important relationship, the typical problems of inadequate protection of reinforced and the current widespread in the construction site of the serious problem of cracking component. These construction, although short-term deficiencies of the bridge will not be the normal use of a clear impact, but the long-term durability of the structure will have a very negative hazards.2) Design theory and structure of the system is not perfect enoughWhile acknowledging the existence of the problem, but it also, it is undeniable that bridge design fields, in particular on the bridge construction and use of the issue of safety there is still much improvement. Structural design first and foremost task is the choice of reasonable economic programmer, followed by the structural analysis and design of components and connections, and access to regulate the safety factor specified or reliability of indicators to ensure the safety of the structure.Many designers often complacent with norms on the structural strength of the safety of the need, and ignore the structural system, structure, structure, structure of materials, structure maintenance, as well as from the structural durability of the design and construction process to make use of that often appear in the man-made wrong areas to strengthen and guarantee the safety of the structure. Some structural integrity and ductility inadequate redundancy small, but some of Schema and the uncertainty of the line, causing partial excessive force; some concrete strength grade too low to protect slice through small diameter steel micromanage , a thin cross-section components of these structures have weakened the durability, it would seriously affect the safety of the structure. Many bridges, although the design specifications meet the requirements of the strength of only 5 to 10 years because of the durability of the problems affecting structural safety. Structural Durability shortage has become one of the most realistic security issues, from design to construction and materials, such as angle of measures to strengthen the durability of the structure.Of the environment and the use of different conditions, different design of the structural system will target different aspects of the layout and structure requirements. Norms can not cover in detail the design staff should solve the various problems in the updated norms faster can also adapt to new understanding, new technologies, new materials, rapid development of the structure of the new requirements. Therefore, reasonable and reliable addition to the structures is designed to meet the requirements of norms, and to design a structure to the correct understanding of nature, rich experience and accurate judgments.And the need to improve efforts in the direction 1) Should pay more attention to the durability of structural problemsBridge in the construction and use of the process, will be subject to environmental, and the erosion of harmful chemical substances, and to bear vehicles, wind, earthquake, fatigue, overloading, human factors, such as external role, and bridge materials used by the self-degradation of performance will continue , resulting in the structure of the different degrees of damage and deterioration. In the field of long-span bridges, and from the country since the 1980s, the construction of a large number of cable-stayed bridge, although so far there collapse or serious damage to the few examples, but has more bridges because of the durability of cable to the problem advance for cable, and this not only affects the use of increased economic losses.Needs to be pointed out is that many of these problems and did not conduct a reasonable durability of the design, which has also prompted renewed awareness of durability of the bridge. Diseases are a lot of examples of that, in addition to construction materials and the reasons for a decisive impact on the durability of the structure from the structural factors (is design) flaws. From the country in the 1990s started to attach importance to the durability of the structure of the study, has also made quite a few successes. Most of these studies and statistics from the analysis of the material point of view, on how to structure and design from the perspective of how and the design and construction staff to be readily accepted and operation of the bridge approach to improving the durability has been little research. Moreover, for a long time, people have always been emphasis on the methods of calculation on the structure; it ignores the details of the overall structure and processing concern. Design and durability of the structure of the structural design of a conventional nature of the difference between the current efforts will be needed on the durability of the qualitative analysis to the quantitative analysis of development.2) Emphasis on the study of fatigue damageBridge structure to withstand the vehicle load and wind load are dynamic load will be in a cycle of change within the structure of the stress, not only will cause the vibration of the structure, but also from the structure of the accumulated fatigue damage. The bridge is not used by the material is uniform and continuous, in fact there are many tiny flaws in the role of cyclic loading, these deficiencies will be progressive development of micro, a merger of injury, and gradually formed in the material macro cracks. If the crack is not effective macro-control, is very likely to cause material, the structure of brittle fracture. Early fatigue damage is not always easy to be detected, but the consequences are often disastrous.Fatigue damage has been considered in the design of steel bridge is the core issue of fatigue caused by the steel structure of steel crack more cases, many caused by fatigue fracture bridge collapse example. Over the past 20 years, fatigue injury research has entered the concrete structure, but by the use of corrosion of reinforced concrete structures dynamic performance and fatigue properties of need to be strengthened. On the fatigue damage of not only refers to the entire structure, the bridge structure often as a matter of fact some of the key parts of local fatigue failure of the entire structure and lead to failure, such as the cable-stayed bridge cables anchoring end of the fatigue damage.3) Pay full attention to the problem of overloading the bridgeThere are three main vehicle overloading: One is the early construction of the old bridge overage load carriers and the other is the passage of vehicular traffic bridge over the original design; the other is illegal overloading of vehicles. The first two are the main reasons for the changes in the design load and the increase in the volume of traffic; users of the latter are illegal overloading of vehicles operating, the latter two phenomena of overloading in road transport in China is more common.On the one hand, overloading the bridge may trigger fatigue. Overloading bridge would increase the rate of fatigue stress injury aggravated, or even some structural damage caused by overloading accidents. On the other hand, due to overloading of the bridge caused internal damage can not be restored, the bridge will be made of the work under normal load conditions change, which could endanger the safety of bridges and durability. For example, the concrete bridge has always been regarded as an adequate durability, but the overloading of the vehicle, cracking may occur; cracks even in the load will be able to divest closed, but the internal structure of concrete has been damage, cracking component from the lower bend, Stiffness decline was in the normal use of load, should not have been cracking or structural cracks have become smaller cracks in excess of the norms to allow a larger cracks or deformation. These will be used for structural performance and long-term durability has a negative impact, in addition to the Traffic Control departments should strengthen management, but also the need for overloading the consequences of research, analysis.4) Actively learn from foreign experience and results Domestic bridge design the main problems is the use of the normal structure of poor performance (referring compared with the design expectations can be attributed to poor performance of the application, including the bridge too much vibration, linear irregularity, joints, diarrhea, excessive structural cracking and deformation, etc.), durability and safety of the poor (including short life span, high maintenance costs, and more frequent accidents, etc.). While these issues have with the current domestic construction quality and management level lower, but to be fair, since this situation can not be resolved in the short term, then as engineers we should address this issue in the premise, are fully taken into account stage of construction and management and materials technology, the use of appropriate security, the appropriate way to ensure that the design of a bridge to the use of the performance, this is a more proactive and effective means. Especially the durability of the bridge and safety of many problems with the structure or the use of material selection are unreasonable and improper handling of the structural details.In European countries (such as Germany, Denmark, etc.), attached great importance to the structure of a performance-based design (PBD, Performance Based Design), which includes structural deformation, cracks, vibration, strong, handsome, durability, fatigue and so on. PBD study is to enable operators in the structure of the process, in addition to the guaranteed minimum security requirements; the idea of the use of performance should be good (including life and durability, corrosion resistance, fatigue resistance, aesthetics, etc.). By their very nature, the European countries PBD theory, research in the use of structure in the course of performance out of service, the performance by the weakening of the reasons for its occurrence and the mechanism of the law, to seek a new structural design concepts and methods.From the point of view of Europeans, PBD seems to be to the durability of the structure at the core of the comprehensive use of performance indicators to consider. This is the domestic engineering should be based on the Enlightenment. At present the domestic design can be seen as static design, built only at the design definition of a structures ability and performance, and during the performance of operating time and the actual deterioration of the performance of the lack of sufficient awareness and consideration; In other words, the economic point of view is to consider only the construction cost, the expense of operating and maintenance costs and service life should be the relative cost-effectiveness.Bridge safety and durability shortage has become an urgent need to address the problem, we should actively learn from successful foreign experiences and practices, in addition to strengthening the construction quality management, bridge design concepts and from the structure and tectonic perspective to the design of durability. At the same time need to study fatigue and overloading the durability of the bridge structure effects.国内桥梁设计存在的主要问题现在，国内的结构设计过程中，有这样的倾向：设计中考虑强度多而考虑耐久性少；重视强度极限状态而不重视使用极限状态，而结构在整个生命周期中最重要的却恰恰是使用时的性能表现；重视结构的建造而不重视结构的维护。实际上，目前的桥梁设计中，对于耐久性更多的只是作为一种概念受到关注，既没有明确提出使用年限的要求，也没有进行专门的耐久性设计。这些倾向在一定程度上导致了当前工程事故频发、结构使用性能差、使用寿命短的不良后果；也与国际结构工程界日益重视耐久性、安全性、适用性的趋势相违背；也不符合结构动态和综合经济性的要求。 桥梁安全性、耐久性差的主要原因 1）施工和管理水平低 国内外多座桥梁的突然破坏与倒塌，已使工程界对桥梁安全性问题倍加关注。一般的看法认为当前的工程事故主要是野蛮施工和管理腐败所导致。对于短期内发生的诸如突然破坏与倒塌，多是由于施工质量没有达到规范和设计要求，典型的问题包括材料强度不足和施工工艺不合格等；也有个别桥梁存在诸如偷工减料、以次充好等严重的管理问题，更是对桥梁安全造成致命的损害。 而大量的桥梁在远没有达到预期使用寿命时，出现了影响正常使用的病害与劣化；特别是一些桥梁在只使用了几年、甚至刚建成不久就出现严重的耐久性不足的问题，这