桥梁设计大赛计算书

桥梁结构设计理论方案作品名称 参赛学校 参赛队员、专业名称指导教师 大庆市大学生结构创新设计竞赛组委会二o——年目录1设计说明根据本次大赛要求及所提供材料，本组成员秉承“安全、节省、承载力高、美观”原则，设计此桥梁“步步精心”结构模型。桥梁以桁架结构为主体，尽量做到受力均匀，拉杆和压杆合理分布。其中“杆件承载力充分利用和桥身自重轻”为此设计最大亮点。设计构思在接到比赛要求最初，本组成员经过分析得出“材料本身承载力强、材质轻、只适合粘结”的结论，初步确定以“平面结构，主梁主要承力，桁架结构”为大体思路。为减轻桥梁自重，我们决定尽量多用拉杆，但在模拟加载过程中，发现此想法难以实现。遂改用另一种减重方式，即尽量使每根杆都受力均匀，所受最大拉（压）力和最小拉（压）力差值最小。结构选型在确定“平面结构、主梁主要承力、桁架结构”为大体思路后，设计步骤如下：根据大赛尺寸要求，初步确定桥梁的跨度、高度和宽度；根据以往经验和资料分析，设计出桥梁大体模型；以实际情况为准，提取计算简图；利用结构力学求解器软件对结构进行模拟加载，计算出各杆所承受轴力及弯矩，以确定桥梁各单元杆件截面尺寸；结合杆件密度，取最优荷重比。详细计算1.3.1设计资料根据大赛要求，可以确定桥梁跨度L=1300mm，净跨L0=1200mm，桥宽B=185mm，由经验和资料初步确定桥高H=150mm，竖向腹杆间距由比赛小车车轮中心轴距离确定，选为120mm。

1.3.2桥梁形式、尺寸及支撑布置根据上述原则，最终确定桥梁如图1-1,1-2图1-2俯视图1・3・3基本假定节点粘结处按照铰接计算；支座简支；荷载取为竖直集中静荷载，分别作用在结点和单元上考虑动荷载影响，计算荷载取为实际荷载1.2倍；忽略桥本身自重，材料材质均匀。定义杆件单元和结点码，下文提到单元和结点码皆基于此定义

1.3.4荷载模拟桥面板近似为均布荷载q=mg/l0=3X10/1300=0.0125N/mm一辆小车加砝码P'=120N,考虑动荷载影响P=1.2P'=144N一辆小车在两榀桁架上荷载分配的原则如图1-5P2=0.75P=108N考虑每辆小车轮距，将一辆小车及砝码的荷载简化为两集中力Q1和Q2Q1=0.5P2=18NQ2=0.5P1=54N则桥梁计算简图如图1-6Ql Q1 彩 般Iq1'fJJJ]]”]]||]]|||J |]JJ]]JJ[[jj|| +]rf\八图1-6按照图1-6将计算简图输入结构力学求解器，将集中荷载依次作用在各单元中间位置，得出各杆件所受最大轴力和弯矩值，依次列在附表1-5，再将集中荷载依次作用在各结点位置，同样得出各杆件所受最大轴力和弯矩值，依次列在附表6-9,此数据作为设计最终依据。

1.3.5计算示例材料性质:木材E=104Mpa，抗拉强度f=30MPat查阅有关资料可知：木材抗压强度f=30MPa，抗弯强度f=20MPa，抗剪强度f=2Mpac m v从表1-9可知，杆件单元共分为三类。一、受拉构件；二、受压构件；三、压弯构件。以下每类杆件均举例说明计算过程，其余不再列出。另在结构中还存在拉弯和受剪构件，因其对结构影响较小，在此忽略不计。一受拉构件，以单元1为例FF=255

厂而=8.5mm2选截面2X6mm的杆件二受压构件，以单元23为例试选5X6杆件i=■yi=■-=62.5/30=2.1A入二lo=192/2.1=133.02>75i血=3000/入=0.172A>N/⑰fc= =19.7mm2c0.17x30选5X6杆件合适。三压弯构件，以单元10为例试选如图1-7截面o图1-7

o图1-7由图1-7知：A=52mm2,Ix=497.33mm4,ix=3.093mm,Iy=169.33mm4,iy=1.81mm,Wx=2I^=99.47h由图1-1知：L=l=120mmox0y强度验算：=0.98<1282.6 + 1267.6=0.98<152x0.9x30十99.47x0.9x20强度满足要求入=I/i=120/0.093=38.8<［入=I/i=120/0.093=38.8<［入］=120xxx入=l/i=120/1.81=66.3<［入］=120yyy刚度满足要求稳定性验算：A平面内K=Wf（K=Wf（1 :mM=.:N ,■）99.47x0.9x20x（1+ ■Af 52x0.9x301267-6 =0.489282.6=（1-K）2=0.261m①=1/［1+①=1/［1+（入/80）2］=1+（等2=0.81B平面外N/（①①B平面外N/（①①A）m282.60.81x0.261x52=25.71N/mm2<f=30N/mm2cN/（①Af）+［M/（①Nf）］N/（①Af）+［M/（①Nf）］2=yc lm282.60.593x52x0.9x30+（1267.6282.6x0.9x20）2=0.4<1满足稳定性要求图1-7截面适合。其余各杆件算法与此相同，不再一一列出，以上公式皆取自《木结构设计规范GB50005—2003》。最终各单元截面选择见附表10、11。2节点设计2.1节点构思经过实验，胶水粘结可以承受的力比材料本身的只强不弱，但考虑到构件用胶水粘结时，接触面积较小，为增加构件之间粘结强度，用1X55mm木板做成垫片，辅助粘结。同样原理，细杆与其他杆件连接时，不用正面粘结，而用侧面。且为增加胶结强度，特别对结点粘结处进行砂纸打磨处理，以增加其摩擦力。并对于多结点交接处，滴加更多胶水，以增加粘结力。2.2节点详图图2-1节点1实际详图图2-2节点2实际详图图2-3节点6实际详图3设计总结结构整体采用桁架结构，既满足受力均匀的要求，同时又保证了计算、施工的方便；计算过程利用结构力学求解器软件，使结果更准确，为设计提供了有效依据；交点多的节点，采用1X55mm薄片做垫片，既充分利用了材料，又使节点承载力有了显著提高；桥梁中只承受拉力的单元做到了足够多，此设计较多的减少了桥身自重；施工精细，节点、杆件处理分毫不差，每根杆件都根据连接做出相应角度坡口，真正地诠释了桥梁的名字“步步精心”4破坏分析动荷载影响可能估计不足，实际加载过程中，可能因此破坏;节点胶水过少，或者因温度变化开裂，造成粘结强度降低；木材本身有结点，截面削弱，虫眼等因素；结构不对称，加载时整体失稳，发生脆性破坏。

附录附表1Q】作用在单元13和14,Q2作用在单元5和6（见图附-1）单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm177.490.000.0077.490.000.30266.000.000.3066.000.000.00382.110.010.0082.110.011.604108.95-0.011.60108.95-0.010.005-100.56-8.790.00-100.5610.71115.626-100.56-9.94115.62-100.569.5692.447-58.76-1.4292.44-58.760.0812.478-58.76-1.1512.47-58.760.35-36.099-72.75-0.25-36.09-72.751.2523.5410-72.75-1.2823.54-72.750.22-40.6011-81.44-0.76-40.60-81.440.74-41.8812-81.442.64-41.88-81.444.14365.5013-203.18-26.66365.50-203.1828.84496.3314-203.18-31.89496.33-203.1823.610.0015220.120.030.00220.120.033.3616141.22-0.013.36141.22-0.010.0017-60.730.000.00-60.730.000.001878.890.000.0078.890.000.0019-78.310.000.00-78.310.000.00206.330.000.006.330.000.0021-7.580.000.00-7.580.000.002210.820.000.0010.820.000.0023-11.580.000.00-11.580.000.0024-27.270.000.00-27.270.000.002526.830.000.0026.830.000.0026-20.660.000.00-20.660.000.0027-1.240.000.00-1.240.000.0028-2.530.000.00-2.530.000.00291.910.000.001.910.000.00

单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1139.720.000.00139.720.000.542117.260.000.54117.260.000.003137.210.010.00137.210.012.044145.53-0.022.04145.53-0.020.005-134.33-1.910.00-134.33-0.41-139.456-134.33-6.83-139.45-134.3312.67210.637-106.04-9.91210.63-106.049.59191.868-106.04-3.37191.86-106.04-1.87-122.999-130.670.87-122.99-130.672.3771.4810-130.67-3.0971.48-130.67-1.59-209.3111-153.854.76-209.31-153.856.26452.1612-153.85-24.77452.16-153.8530.73809.4613-237.73-35.76809.46-237.7319.74-151.6414-237.730.51-151.64-237.732.010.0015257.560.030.00257.560.033.7016232.60-0.013.70232.60-0.010.0017-19.230.000.00-19.230.000.001824.940.000.0024.940.000.0019-97.430.000.00-97.430.000.002022.620.000.0022.620.000.0021-14.490.000.00-14.490.000.002221.470.000.0021.470.000.0023-17.960.000.00-17.960.000.0024-33.000.000.00-33.000.000.00258.310.000.008.310.000.0026-6.420.000.00-6.420.000.0027-12.970.000.00-12.970.000.0028-5.460.000.00-5.460.000.0029-31.030.000.00-31.030.000.00

单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1205.960.000.00205.960.000.802170.050.000.80170.050.000.003164.870.010.00164.870.012.174161.26-0.022.17161.26-0.020.005-148.85-3.060.00-148.85-1.56-277.456-148.851.19-277.45-148.852.69-44.287-146.31-6.05-44.28-146.3113.45400.138-146.31-12.92400.13-146.316.5819.949-187.32-1.5119.94-187.32-0.01-71.1610-187.321.70-71.16-187.323.20222.8211-205.39-20.82222.82-205.3934.681054.4212-205.39-35.461054.42-205.3920.04129.4113-214.55-5.56129.41-214.55-4.06-447.4514-214.552.98-447.45-214.554.480.0015232.440.020.00232.440.023.1416241.62-0.013.14241.62-0.010.00177.040.000.007.040.000.0018-9.200.000.00-9.200.000.0019-28.250.000.00-28.250.000.0020-0.920.000.00-0.920.000.0021-29.840.000.00-29.840.000.002227.650.000.0027.650.000.0023-38.010.000.00-38.010.000.0024-9.410.000.00-9.410.000.0025-3.620.000.00-3.620.000.00262.760.000.002.760.000.0027-26.370.000.00-26.370.000.00281.710.000.001.710.000.0029-70.140.000.00-70.140.000.00

单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1251.430.000.00251.430.001.172215.190.001.17215.190.000.003181.610.010.00181.610.012.414180.03-0.022.41180.03-0.020.005-166.18-3.040.00-166.18-1.54-274.766-166.18-0.34-274.76-166.181.16-226.157-169.723.13-226.15-169.724.63239.538-169.72-10.95239.53-169.728.5595.719-248.74-6.3795.71-248.7413.13501.7510-248.74-25.43501.75-248.7430.07779.7811-205.82-30.33779.78-205.8225.17470.6612-205.82-7.29470.66-205.82-5.79-314.2013-199.73-0.84-314.20-199.730.66-324.6914-199.731.96-324.69-199.733.460.0015216.380.020.00216.380.022.8916218.10-0.012.89218.10-0.010.00171.290.000.001.290.000.0018-1.730.000.00-1.730.000.00197.190.000.007.190.000.0020-73.020.000.00-73.020.000.0021-4.320.000.00-4.320.000.002253.700.000.0053.700.000.0023-72.800.000.00-72.800.000.00243.310.000.003.310.000.0025-1.590.000.00-1.590.000.00261.190.000.001.190.000.0027-15.580.000.00-15.580.000.0028-38.570.000.00-38.570.000.0029-32.460.000.00-32.460.000.00附表5Q1+Q2作用在单自元9和10（见图附-5）单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1247.100.010.00247.100.011.392247.10-0.011.39247.10-0.010.003200.690.010.00200.690.012.654197.87-0.022.65197.87-0.020.005-182.64-3.380.00-182.64-1.88-315.226-182.640.27-315.22-182.641.77-192.937-185.340.78-192.93-185.342.28-9.168-185.342.20-9.16-185.343.70345.209-282.64-29.06345.20-282.6444.441267.6410-282.64-44.441267.64-282.6429.06345.2011-185.34-3.70345.20-185.34-2.20-9.1612-185.34-2.28-9.16-185.34-0.78-192.9313-182.64-1.77-192.93-182.64-0.27-315.2214-182.641.88-315.22-182.643.380.0015197.870.020.00197.870.022.6516200.69-0.012.65200.69-0.010.00172.150.000.002.150.000.0018-2.830.000.00-2.830.000.00190.130.000.000.130.000.0020-98.860.000.00-98.860.000.002156.900.000.0056.900.000.002256.900.000.0056.900.000.0023-98.860.000.00-98.860.000.00240.130.000.000.130.000.0025-2.830.000.00-2.830.000.00262.150.000.002.150.000.0027-0.080.000.00-0.080.000.0028-88.870.000.00-88.870.000.0029-0.080.000.00-0.080.000.00单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1108.770.000.00108.770.000.42291.690.000.4291.690.000.003112.970.010.00112.970.011.924133.21-0.011.92133.21-0.010.005-122.96-3.050.00-122.96-1.55-276.176-122.960.86-276.17-122.962.36-82.547-82.140.46-82.54-82.141.9662.738-82.14-1.8562.73-82.14-0.35-69.839-101.660.16-69.83-101.661.6639.4610-101.66-1.9139.46-101.66-0.41-99.5711-116.870.81-99.57-116.872.3187.7612-116.87-2.4487.76-116.87-0.94-114.9413-237.00-4.96-114.94-237.00-3.46-620.3814-237.004.42-620.38-237.005.920.0015256.760.030.00256.760.033.8216196.85-0.013.82196.85-0.010.0017-46.120.000.00-46.120.000.001859.890.000.0059.890.000.0019-103.800.000.00-103.800.000.002012.950.000.0012.950.000.0021-11.390.000.00-11.390.000.002215.960.000.0015.960.000.0023-15.300.000.00-15.300.000.0024-35.450.000.00-35.450.000.002520.230.000.0020.230.000.0026-15.580.000.00-15.580.000.0027-3.820.000.00-3.820.000.0028-3.570.000.00-3.570.000.0029-4.750.000.00-4.750.000.00

单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1172.010.000.00172.010.000.662143.340.000.66143.340.000.003154.210.010.00154.210.012.094152.79-0.022.09152.79-0.020.005-141.03-2.720.00-141.03-1.22-236.526-141.03-0.15-236.52-141.031.35-164.107-128.211.13-164.10-128.212.6361.668-128.21-2.0961.66-128.21-0.59-99.339-159.260.41-99.33-159.261.9139.8010-159.26-2.0739.80-159.26-0.57-118.2311-185.710.62-118.23-185.712.1245.8112-185.71-3.3945.81-185.71-1.89-271.4213-224.45-1.69-271.42-224.45-0.19-383.9414-224.452.45-383.94-224.453.950.0015243.170.030.00243.170.033.3716246.64-0.013.37246.64-0.010.00172.640.000.002.640.000.0018-3.480.000.00-3.480.000.0019-67.170.000.00-67.170.000.002021.920.000.0021.920.000.0021-20.410.000.00-20.410.000.002225.490.000.0025.490.000.0023-24.210.000.00-24.210.000.0024-22.630.000.00-22.630.000.0025-1.430.000.00-1.430.000.00261.070.000.001.070.000.0027-22.720.000.00-22.720.000.0028-3.980.000.00-3.980.000.0029-59.510.000.00-59.510.000.00

单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1234.780.000.00234.780.000.972194.800.000.97194.800.000.003172.840.010.00172.840.012.294170.81-0.022.29170.81-0.020.005-157.66-2.990.00-157.66-1.49-268.736-157.660.06-268.73-157.661.56-172.017-159.981.30-172.01-159.982.8074.318-159.98-2.6674.31-159.98-1.16-155.249-217.011.06-155.24-217.012.5662.0410-217.01-2.9862.04-217.01-1.48-205.9211-211.601.32-205.92-211.602.8242.5512-211.60-2.8242.55-211.60-1.32-206.4013-207.60-2.06-206.40-207.60-0.56-363.2014-207.602.28-363.20-207.603.780.0015224.910.020.00224.910.023.0116228.62-0.013.01228.62-0.010.00172.830.000.002.830.000.0018-3.730.000.00-3.730.000.00190.900.000.000.900.000.0020-37.110.000.00-37.110.000.0021-28.460.000.00-28.460.000.002235.550.000.0035.550.000.0023-55.750.000.00-55.750.000.00240.680.000.000.680.000.0025-2.050.000.00-2.050.000.00261.550.000.001.550.000.0027-23.470.000.00-23.470.000.0028-5.540.000.00-5.540.000.0029-59.650.000.00-59.650.000.00

单兀码杆端1杆端2轴力N剪力N弯矩N.mm轴力N剪力N弯矩N.mm1255.040.010.00255.040.011.332232.37-0.011.33232.37-0.010.003191.170.010.00191.170.012.534188.94-0.022.53188.94-0.020.005-174.40-3.210.00-174.40-1.71-295.326-174.40-0.02-295.32-174.401.48-207.927-177.461.86-207.92-177.463.36105.138-177.46-2.75105.13-177.46-1.25-135.469-273.70-0.23-135.46-273.701.27-73.3010-273.70-1.73-73.30-273.70-0.23-191.0011-194.871.88-191.00-194.873.38124.0812-194.87-3.72124.08-194.87-2.22-232.0013-191.10-1.52-232.00-191.10-0.02-324.2814-191.101.95-324.28-191.103.450.0015207.030.020.00207.030.022.7716209.63-0.01