电大桥梁工程试题B答案小抄

1、专业好文档桥梁工程试卷2答案一、填空题（每空1分，共20分）（请将答案填写在答题纸上）1简支梁（板）的架设，从架梁的工艺类别划分有陆地架梁法 、浮吊架梁法和 架桥机架梁法 。2作用代表值包括 标准值 、 频遇值 、 准永久值 。3桥台的常见型式有 重力式桥台 、 轻型桥台 、 框架式桥台 和 组合式桥台 等。4公路桥面构造包括 桥面铺装 、 排水防水系统 、 人行道 、 路缘石 （或填：安全带、栏杆、灯柱、安全护栏、伸缩装置 任一个）等。5钢桁梁的主桁主要由 上弦杆 、 下弦杆 、 腹杆 和节点组成。6悬索桥主要由 索塔 、 拉索 、 加劲梁 和 锚碇 等组成。二、名词解释（每题3分，共15分

2、）1 净跨径：在设计洪水位上相邻两桥墩（台）之间的距离。2 车辆制动力：指车辆在刹车时为克服车辆的惯性力而在路面或轨道与车轮之间发生的滑动摩擦力。3 模板：是用于浇筑混凝土、形成结构形状和尺寸的临时性结构。4 上水平纵向联结系：在两片主桁对应的弦杆之间，加设若干水平布置的撑杆，并与主桁弦杆共同组成一个水平桁架，以承受横向水平力，这个水平桁架就叫做水平纵向联结系，简称平纵联。5 持久状态：指桥涵使用过程中长期承受结构自重、汽车荷载等作用的状态。在该状态下要求对设想的结构所有功能进行设计。三、简答题（每题5分，共35分）1预应力混凝土简支梁与钢筋混凝土简支梁相比有何优点？答：1）采用高强度钢筋，可

3、节约一定的普通钢筋；（1.5分）2）预加压应力可大幅度提高梁体的抗裂性，并增加了梁的耐久性；（1.5分）3）由于利用高标号混凝土，截面尺寸减小，梁体自重减轻，可以增大跨越能力，也有利于运输和架设；（1分）4）混凝土全截面受压，充分发挥了混凝土抗压性能的优势，也提高了梁的刚度。（1分）2支座的作用是什么？连续梁桥的固定支座布置有何要求？ 答：1）支座的作用是把上部结构的各种荷载传递到墩台上，并能够适应活载、混凝土收缩与徐变等因素所产生的变位（位移和转角），使上下部结构的实际受力情况符合设计的计算图式。（4分）2）连续梁桥每联只设一个固定支座。曲线连续梁中间常设单支点支座，仅在一联范围的梁的端部（

4、或桥台上）设置双支座。（1分）3作用效应组合的基本原则是什么？答：应只涉及结构上可能同时出现的作用效应（3分），并以桥梁在施工或运营时可能处于最不利受力状态为原则。（2分）4在后张法预应力简支梁中，预应力筋大部分在梁端附近都要弯起，这是为什么？答：在后张法预应力简支梁中，跨中截面为了获得最大的承载能力和较大的预压应力，预应力筋尽可能地靠近梁的下缘布置，在支点附近由于梁体自重弯矩减小，在张拉锚固阶段梁体上缘可能会出现过高的拉应力，可能导致开裂，因此为减小预应力产生的弯矩，所以大部分预应力钢筋在梁端附近都要弯起以减小偏心（3分）。再者，由于预应力钢筋靠锚具锚固在梁端，锚具和张拉千斤顶需要一定的工作

5、面积，锚具垫板下混凝土具有较高的局部压应力，可能造成锚下混凝土开裂，因此也需要将锚具在梁端分散布置，使得大部分预应力钢筋在梁端附近都要弯起（2分）。5桥梁伸缩装置的作用是什么？答：桥跨结构在气温变化、活载作用、混凝土收缩和徐变等影响下将会发生伸缩变形。（1分）桥梁伸缩装置作用就是为满足结构按照设计的计算图式变形，同时又能保证车辆平顺通过。（4分）6试述桥梁工程设计的基本原则以及各原则之间的关系。答：1）桥梁设计的原则为：安全性、适用性、经济、美观。（3分）2）安全是第一前提。在满足安全、适用要求的条件下，考虑经济。在安全、适用和经济的前提下，尽可能使桥梁具有优美的造型。（2分）7在什么条件下应

6、该对扩大基础的基底应力进行重分布计算？为什么需要进行应力重分布计算？答：当基底应力出现小于零的情况下，应进行基底应力重分布计算（2分）。这是由于当部分基底应力小于零时，意味着这部分基础不再承受压力，而导致截面内压应力峰值可能增大，因此，为保证基底应力满足安全要求，需要进行应力重分布计算。（3分）四、计算题（共30分）1如图所示为一座桥面板为铰接的t形截面简支梁桥，桥面铺装厚度为0.1m，净跨径为1.4m，试计算桥面板根部在车辆荷载作用下的单位宽度（1m）活载弯矩和剪力。（车辆前后轮着地宽度和长度分别为：b1=0.6m和a1=0.2m；车辆荷载的轴重p=140kn）图 截面示意图（单位：m）（1

7、）荷载轮重分布在桥面板顶面的尺寸：沿纵向：（2分）沿横向：（2分）板顶分布荷载：（5分）（2）板的有效宽度悬臂板边缘：（2分）悬臂板根部：（2分）（3）悬臂板根部内力每米宽悬臂板在根部的活载弯矩：（6分）每米宽悬臂板在根部的活载剪力：（6分）2（5分）某桥墩基础为扩大基础，基底截面如下图所示，其中纵向d=300cm，横向b=600cm，竖向力n=2500kn，纵向水平力p=650kn，纵向弯矩m=1950kn-m。基础与土壤的摩擦系数f=0.33。检算基底的滑动稳定性（滑动稳定性系数）和倾覆稳定性（倾覆稳定性系数）mdb图2 基础平面图解：解：1）抗滑动稳定验算：（3分）故不满足要求。2）抗倾

8、覆稳定性验算（2分）满足要求。winger tuivasa-sheck, who scored two tries in the kiwis 20-18 semi-final win over england, has been passed fit after a lower-leg injury, while slater has been named at full-back but is still recovering from a knee injury aggravated against usa.both sides boast 100% records heading int

9、o the encounter but australia have not conceded a try since josh charnleys effort in their first pool match against england on the opening day.aussie winger jarryd hayne is the competitions top try scorer with nine, closely followed by tuivasa-sheck with eight.but it is recently named rugby league i

10、nternational federation player of the year sonny bill williams who has attracted the most interest in the tournament so far.the kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the world cup in both rugby league and rugby union after triumphing with the

11、all blacks in 2011.id give every award back in a heartbeat just to get across the line this weekend, said williams.the (lack of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will

12、attend citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya toure, he told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against

13、 cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footballs governing body, has also ordered an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side ad

14、ded: we found no racist insults from fans of cska. baumgartner the disappointing news: mission aborted.the supersonic descent could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no p

15、recipitation or humidity and limited cloud cover. the balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than th

16、e cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step

17、out onto something resembling an olympic diving platform.they blew it in 2008 when they got caught cold in the final and they will not make the same mistake against the kiwis in manchester.five years ago they cruised through to the final and so far history has repeated itself here - the last try the

18、y conceded was scored by englands josh charnley in the opening game of the tournament.that could be classed as a weakness, a team under-cooked - but i have been impressed by the kangaroos focus in their games since then.they have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. theyve been great at all the unglamorous stuff that often goes unnoticed in the