v桥梁的设计荷载及荷载组合.doc

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1、and urban medical rescue work, conscientiously strengthen leadership, sound system. County Government was set up by the magistrate as head of the Government, civil affairs, finance, health, labour and other related departments mainly responsible as members of the leading group for rural cooperative

2、medical care. Formed a Government, the home of the County supervisors, operation mechanism of collaboration. This year, the County started implementing Medicaid one-stop real time service, medical assistance, basic medical insurance, Effective convergence of insurance and medical relief implementati

3、on plan for 2015 I counties to reconsider an amendment will be accepted to extend the hours of medical aid on June 30, and county-wide poverty population range of serious disease including medical assistance, protection of agricultural and pastoral areas in 22 major diseases and implement home healt

4、h aid secondary aid, to achieve a longitudinal and transverse to the side of Medicaid coverage. So far, the total investment 2.8772 million Yuan relief 955 visits the sick poor people in urban and rural areas, 155,000 to rescue 65 people in patients with serious diseases. (D) efforts to the developm

5、ent of social welfare service, constantly improve the five-guarantee system. Implementing regulations of the rural five-guarantee work, further increase the intensity of day-to-day management and services to the five objects, ensure that the five should do, according to Shi Bao on the basis of furth

6、er perfecting rural five-guarantee system, raise the level of support. So far, funding for any County 89 wubaohu 524,700. Meanwhile, as a region-wide severe disabilities aged care subsidies this year pilot counties, our County has been seriously disabled elderly nursing allowance pilot program, comp

7、leting survey work for severely disabled older people throughout the County, and in June began issuing subsidies, up to now, the nursing allowance total 79200 Yuan. For a better implementation of the system of funding for raising, my County in 2015 revised Burqin County of new rural cooperative medi

8、cal care program, will include the full scope of medical aid. Existing 149 orphans in our County are scattered for the community support officers, standard 700 Yuan/month/person, up to now, the total life subsidies for the 149 orphans 983,400 winter coal subsidies for 180,000 yuan. (E) optimize resc

9、ue, relief work strengthening the vagrants and beggars. Under the voluntary aided, voluntary aid bailout principles, further strengthening the work of relief for vagrants and beggars, vagrants and beggars provide assistance such as accommodation, return travel by car, especially for children, the el

10、derly, and the sick, disabled people and young homeless person to implement a point-to-point first aid, after clearing protective relief, and safeguard the basic rights of bailouts. Meanwhile, coordinating public security, urban management, manipulation, coercion against organizations such as the us

11、e of minors, begging for the disabled and to disrupt public order and other illegal panhandling. Up to now, a total of 31,000 toRelief for vagrants and beggars of 42 passengers. (Vi) with a focus on safeguarding the peoples livelihood, promote home projects. Adhere to the project as the starting poi

12、nt, positive projects, schedule, quality, safety, and to quicken the construction of projects, has made a new breakthrough. In 2015, two projects, Burqin County community day care centre for the elderly in friendship peak project, Burqin County hemu kanas Mongolia桥梁的设计荷载及荷载组合(1) 如图:一、桥梁的设计荷载选定荷载和进行荷

13、载分析是比结构分析更为重要的问题。因为它关系到桥梁结构在它的设计使用期限内的安全和桥梁建设费用的合理投资。近年来,由于交通量的不断增加,大型超重车辆的不断出现,风载、地震荷载的重要性愈显突出等,导致实际与可能作用在桥梁结构上的荷载越来越复杂,这就为桥梁荷载的选定和分析造成了困难,常因初始设计荷载选定的滞后,而造成桥梁早期破坏或加固。我国现行的公路桥涵设计通用规范(JTJ021-85)中,将作用在桥梁上的荷载分为三大类:1永久荷载(恒载) 在设计使用期内,其值不随时间变化,或其变化与平均值相比可以忽略不计的荷载。它包括结构重力、预加应力、土的重力及侧压力、混凝土收缩及徐变影响力,基础变位影响力和

14、水的浮力。2可变荷载(活载) 在设计使用期内,其值随时间变化,且其变化与平均值相比不可忽略的荷载。按其对桥涵结构的影响程度,又分为基本可变荷载和其他可变荷载。基本可变荷载包括汽车荷载及其引起的冲击力,平板挂车(或履带车)荷载,人群荷载,离心力,以及所有车辆所引起的土侧压力。其他可变荷载包括汽车制动力,风力,流水压力,冰压力,温度影响力和支座摩阻力。3偶然荷载 在设计使用期内,不一定出现,但一旦出现其值很大且持续时间较短的荷载,它包括船只或漂浮物撞击力,地震作用。下面具体讲述各种荷载的意义:(一)永久荷载结构物的重力及桥面铺装、附属设备等外加重力均属结构重力,可按照结构的实际体积或设计时所假定的

15、体积与材料密度计算。作用在墩台上的土重力,土侧压力可参照公路桥涵通用规范(JTJ021-85)附录一、二和公路桥涵地基与基础设计规范(JTJ024-85)附录二中规定计算。对于预应力混凝土结构,预加应力在结构使用阶段设计时,应作为永久荷载计算其效应,计算时应考虑相应阶段的预应力损失;在结构承载能力极限状态设计时,预应力不作为荷载,而将预应力筋作为普通钢筋计入结构抗力。混凝土收缩、徐变和基础变位将使超静定结构产生内力,这些力的计算可根据公路桥涵通用规范(JTJ021-85)中有关规定计算。水的浮力对桥梁墩台的影响,当墩台位于透水性地基上时,验算墩台的稳定性,应采用设计水位浮力,而验算地基应力时,

16、仅考虑低水位时的浮力或不考虑水的浮力;当基础嵌入不透水性地基上时,可不考虑水的浮力;当不能肯定地基是否是透水时,应以透水和不透水两种情况分别计算与其他荷载组合,取其最不利者。可变荷载1基本可变荷载1)公路桥梁汽车荷载(1)公路桥涵通用规范(JTJ021-85)的规定:该规范把大量、经常出现的汽车荷载,作为设计荷载;把偶然,个别出现的平板挂车或履带车作为验算荷载。汽车荷载以汽车车队表示,分为汽车-10级、 汽车-15级、汽车-20级、汽车-超20级四个等级。车队的纵向排列和横向布置如图1-5-1和图1-5-2所示。荷载级别的数字表示一辆主车的重量,以吨计。每级车队中有一辆是重车,其前后都是主车,

17、主车的数量在计算跨长内不限。图1-5-1 各级汽车的纵向排列(重力单位:KN;尺寸单位:m) 图1-5-2 各级汽车的平面尺寸和横向布置(尺寸单位:m)验算荷载分为800KN、1000KN、和1200KN平板挂车(简称挂车80、挂车100和挂车120)以及履带500KN(简称履带50)四种。其纵向排列和横向布置见图1-5-3。(2)公路工程技术标准(JTG B01-2003)的规定2003年新颁布的公路工程技术标准中对于车辆荷载进行了新的规定:取消挂车或履带车荷载,同时将汽车荷载分为公路级和公路级两个等级,其等级按照表1-5-1确定。汽车荷载由车道荷载和车辆荷载组成。车道荷载由均布荷载和集中荷

18、载组成。桥梁结构的整体计算采用车道荷载;桥梁结构的局部加载、涵洞、桥台和挡土墙土压力等的计算采用车辆荷载。车道荷载与车辆荷载的作用不得叠加。车道荷载的计算图式如图1-5-4所示: 公路级车道荷载的均布荷载标准值为;集中荷载标准值按以下规定选取:桥涵计算跨径小于或等于5m时,;桥涵计算跨径大于或等于50m时,;桥涵计算跨径大于5m,小于50m时,采用直线内插求得。计算剪力效应时,上述荷载标准值应乘以1.2的系数。公路级车道荷载的均布荷载标准值和集中荷载标准值,为公路级车道荷载的0.75倍。车辆荷载:公路级和公路级汽车荷载采用相同的车辆荷载标准值。车辆荷载布置如图1-5-5所示。其主要技术指标见表

19、1-5-5。表1-5-2 车辆荷载主要技术指标 车道荷载横向分布稀疏,应按设计车道数如图1-5-6布置车辆荷载进行计算。汽车外侧车轮的中线,离人行道或安全带边缘的距离不得小于0.5m。 图1-5-6 车辆荷载横向布置(尺寸单位:m) 当桥梁横向布置车队数等于或大于2时,由于单向并行通过的机率较小,应考虑计算荷载效应的横向折减,但折减后的效应不得小于用两条设计车道的荷载效应。一个整体结构上的计算荷载横向折减系数见表1-5-3。 当桥梁计算跨径大于150 m时,应按表1-5-4考虑车道荷载的纵向折减。桥梁为多跨连续结构时,整个结构应按最大计算跨径的纵向折减系数进行折减。(3)两种规范的比较由上述两

20、种规范对车辆荷载的规定,可以看出1985年的规定比较符合车辆实际行驶排列情况,而2003年的规范对于车辆荷载从形式上不考虑挂车和履带车荷载,同时汽车荷载计算模式单一化,使得桥梁结构计算更为简便。说明:在具体桥梁结构计算时,车辆及人群荷载等荷载布置以最新颁布的设计规范为计算依据。2)城市桥梁汽车荷载我国建设部1998年制定了城市桥梁设计荷载标准(CJJ77-98),该标准适用于城市内新建、改建的永久性桥梁与涵洞,高架道路及承受机动车的结构物荷载设计。荷载采用两级荷载标准,即城A级、城B级。城A级总轴重700KN,适用于快速路及主干路。城B级荷载总轴重300KN,适用于次干路及支路。标准中规定:在

21、城市桥梁设计中,汽车荷载可分为车辆荷载和车道荷载。车辆荷载主要用于桥梁的横隔梁,行车道板,桥台或挡土墙后土压力的计算。车道荷载主要用于桥梁的主梁,主拱和主桁架等的计算。当进行桥梁结构计算时不得将车辆荷载与车道荷载的作用叠加。(1)车辆荷载:城A级和城B级标准车辆,平面布置见图1-5-7及图1-5-8。图1-5-7 城-A级标准车辆纵、平面布置 图1-5-8 城-B级标准车辆纵、平面布置(2)车道荷载:城A级和城B级车道荷载应按均布荷载加一个集中荷载P计算,其纵横向布置见(图1-5-9a,b)。图中,表示弯矩效应计算时采用的均布荷载标准值,表示剪力效应计算时采用的均布荷载标准值,均布荷载和集中荷

22、载的标准值可按表1-5-5取值。车道荷载的单向布载宽度应为3.0m,为简化桥梁横向影响线的计算,车道荷载应按照(图1-5-c )所示的等效荷载车轮集中力形式布置。当设计车道数目大于2时,应计入车道的横向折减系数。加载车道位置应选在结构能产生最不利的荷载效应之处。表1-5-5 车道荷载的均布荷载和集中荷载标准 注:在计算剪力时,当跨径大于20m小于150m,且车道数等于或大于4条,城A级,城B级车道荷载应分别乘以1.25,1.30增长系数。3)人群荷载 根据公路工程技术标准(JTG B01-2003),设有人行道的公路桥梁,当用汽车荷载计算时,应同时计入人行道上的人群荷载。当桥梁跨径小于或等于5

23、0 m时,人群荷载标准值为3.0 KN/m2;当桥梁跨径等于或大于150 m时,人群荷载标准值为2.5KN/m2;桥涵计算跨径大于50m,小于150m时,可采用直线内插求得。对于跨径不等的连续结构,采用最大计算跨径的人群荷载标准值。城镇郊区行人密集地区的公路桥梁,人群荷载标准值为上述标准值的1.15倍。专用人行桥梁,人群荷载标准值为3. 5 KN/m2。城市桥梁在计算人行道板、局部构件的人群荷载时,应按5KN/m2的均布荷载或1.5KN的竖向集中力分别计算,取其不利者。当计算梁、桁架、拱及其他大跨结构的人群荷载,需根据加载长度及人行道宽度来确定,参见城市桥梁设计荷载标准(CJJ77-98),且

24、在任何情况下不得小于2.4KN/m2。在设计栏杆时,对于公路桥梁作用在栏杆立柱顶上的水平推力一般采用0.75KN/m;作用在栏杆扶手上的竖向力一般采用1KN/m;对于城市桥梁由于人流量较大,作用在栏杆扶手上的活载,其竖向活载采用1.2KN/m,水平向外荷载采用1.0KN/m。两者应分别考虑,不得同时作用。4)汽车冲击力冲击作用车辆以一定速度在桥上行驶,由于桥面不平整,车轮不圆以及发动机抖动等原因,会使桥梁结构引起振动,致使桥梁产生的应力与变形比相应的静载引起的要大,这种由于荷载的动力作用使桥梁发生振动而造成内力加大的现象称为冲击作用。冲击系数鉴于目前对冲击作用还不能从理论上作出符合实际的精确计

25、算,一般根据在现代桥梁上所做的振动试验结果而近似地以汽车荷载增大系数,即冲击系数来计算荷载的冲击影响。表1-5-6列出了公路钢筋混凝土和石砌桥梁的冲击系数值。冲击系数1+是随跨径或荷载长度的增大而减小的,当在表列数值之间时,可用直线内插法求得。表1-5-6 钢筋混凝土、混凝土和砖石砌桥涵的冲击力城市桥梁值可按下列公式计算:对于车道荷载 (1-5-1)式中: 跨径(m),当对于车辆荷载=0.6686-0.3032log (1-5-2)但的最大值不得超过0.4。鉴于结构物上填料能起缓冲和扩散的作用,故对于拱桥,涵洞及重力式墩台,当填料厚度(包括路的厚度)等于或大于0.5m时,可不计冲击力。5)离心

26、力桥规中规定:当弯道桥的半径等于或小于250 m时,应计算离心力。离心力为车辆荷载(不计冲击力)乘以离心力系数C,离心力系数由下式计算:(1-5-3)式中:V计算行车速度,应按桥梁所在路线等级的规定采用(Km/h);R曲线半径(m)。在计算多车道的离心力时,应按表1-5-3横向折减系数折减。离心力的着力点在桥面以上1.2m(为计算简便也可移至桥面上,不计由此引起的力矩)。6)车辆荷载引起的土侧压力汽车引起的土压力,即是这些车辆荷载在桥台或挡土墙后填土的破坏棱体上引起的土侧压力,可按换算的等代均布土层厚度来计算,具体办法见公路桥涵设计通用规范(1985年)第2.3.6条规定。national r

27、ural home for the project. According to the Countys general plan, integration of resources, in 2014, new Burqin County Senior Center project, the current project has been completed, internal equipment purchasing and working culture decoration is complete, start review acceptance, put into use by the

28、 end. My County is based on the basic livelihood needs to actively seek public service facilities, 2015 to declare mutual assistance in building rural old happiness in Burqin County 8 projects, invested 400,000 yuan lottery ticket equipment purchased during the year for the rural mutual happiness. W

29、hile actively works with development and reform Department, fighting for construction project of Burqin County disaster relief material reserves, at present the project has completed feasibility study procedures, feasibility study approval. In 2015, the County invested 500,000 yuan, perfect Muslim f

30、uneral home facilities, upgrading services and project acceptance. Meanwhile, seeking Burqin County non-Muslim funeral home works, so far the project has completed the project site, is for the early procedures. (VII) working steadily among others, the full implementation of the special care and plac

31、ement policy. To further improve the quality of activities among others as the goal, close to military practice, deepening the County among others. During the Spring Festival, the Eid al-Adha period with condolences resident was paid 125,000 yuan forces and the soldiers back, special care and activi

32、ties, while increasing work of demobilized stability control, regular or irregular visit condolence activities, understand the ideological trends, solve difficulties in life, increase the spear Shield troubleshooting to resolve and implement a policy, effectively safeguarding social stability. As of

33、 now, 148 of the County issued living allowances 1.0648 million Yuan, 4 retired veteran cadres to pay health insurance premiums 10,770, pay health insurance premiums for the 3 families of retired veteran cadres 7,800 Yuan, 70 rural veterans aged over 60 issued living subsidies of 176,000 yuan, issue

34、d for 27 veterans a one-time employment economic benefit of 1.286 million Yuan. (H) strengthen measures, promoting division names and basic power. Division name: according to the autonomous regions urbanization development plans County finished Wo yimoke Xiang town, Xiang to withdraw monthly, has pa

35、ssed the Home Office review of the autonomous region, continued this year to complete the scope Stack Xiang Jian Zhen Xiang withdrawal of declarations, while completing yili State Government approval, reported to the Home Office for approval. Meet the needs of Burqin Countys economic and social deve

36、lopment, address some villages due to the large population base and wide distribution, is not easy to manage, as well as the jurisdiction of the new pastoral settlement from villages far, masses of inconvenience problem. I Board this year and all townships and organizational Department jointly organ

37、ized, on the part of the township (town) villages (communities) splits and reorganization, achieving new villages throughout the County, 11 communities 1. After adjustment, the County has jurisdiction over 7 townships (towns) 74 villages, 7 community. This year, the re-inspection work for peace throughout the County the county seat, I work closely with the campaigns in villages and towns border the unit complete 5 2 town within the administrative area of the County Planning, 12 and 5 pillars of joint inspection of the border. Grass-roots democracy: one is to promote grass-roots9

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