简支梁桥的计算-3荷载横向分布计算偏心压力法A.ppt

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1、,BRIDGE ENGRGPART II,Part 2 RC&PC beam bridge第二篇 钢筋混凝土和预应力混凝土梁式桥,Chapter 3 第三章 Analysis of simple supported beam bridge 简支梁桥的计算,3）荷载横向分布系数计算方法杠杆原理法 Method based on mechanics of leverage偏心压力法Method based on stiffness transverse connection横向铰接梁（板）法横向刚接梁法比拟正交异性板法,3.3 Computation of Coefficients of Tran

2、sverse Distribution of Loads 荷载横向分布计算,3.3 Computation of Coefficients of Transverse Distribution of Loads 荷载横向分布计算,3.Method based on stiffness transverse connection偏心压力法,1）Assumption 基本假设 The stiffness of the transverse connection is very strong,the deformation of the connection is negligible.横梁刚性极大

3、,刚性横梁的微小变形可以忽略不计,3.3 Computation of Coefficients of Transverse Distribution of Loads 荷载横向分布计算,3.Method based on stiffness transverse connection偏心压力法,2）Suitability of the assumption 基本假设的适用范围 试验证明，当B/L0.5(称为窄桥)及具有多道横隔梁时，刚性横隔梁假设是成立的。,3.3 Computation of Coefficients of Transverse Distribution of Loads

4、荷载横向分布计算,3）Theory 原理,P,P,L,e,3.Method based on stiffness transverse connection偏心压力法,3.Method based on stiffness transverse connection偏心压力法,3）Theory 原理Pointed load at the center P=1 中心荷载作用 Based on the assumption,the deflections of each girder will be the same under the centric load 由刚性横梁假设，中心荷载作用下，各

5、梁的挠度相等。,w1,w2,R1,R2,R3,R4,R5,w1=w2=w3=w4=w5,3.Method based on stiffness transverse connection偏心压力法,P=1,w1,w2,R1,R2,R3,R4,R5,The relation between deflection and the centric load简支梁在集中荷载作用下的挠度：,3）Theory 原理Pointed load at the center P=1 中心荷载作用,3.Method based on stiffness transverse connection偏心压力法,w1,w

6、2,R1,R2,R3,R4,R5,Static equilibrium equation in vertical 竖向静力平衡：,3）Theory 原理Pointed load at the center P=1 中心荷载作用,3.Method based on stiffness transverse connection偏心压力法,3）Theory 原理Moment caused by eccentric load 偏心力矩作用M=Pe=eThe deflection of the girders各梁竖向挠度：,M=Pe=e,R1,R2,R4,R5,wi,ai,3.Method based

7、 on stiffness transverse connection偏心压力法,M=Pe=e,R1,R2,R4,R5,wi,ai,3）Theory 原理Moment caused by eccentric load 偏心力矩作用M=Pe=eStatic equilibrium equation about the moment弯矩静力平衡：,3.偏心压力法,3）Theory 原理C.Total action of the eccentric pointed load 偏心荷载对各主梁的综合作用When the load is applied on the k girder当荷载作用于第k号梁

8、(e=ak)：,R1k,R2k,R5k,（3）,R3k,R4k,R1,R2,R4,R5,ak,P,3.Method based on stiffness transverse connection偏心压力法,a1,P,-a1,R11,R51,3）Theory 原理C.Total action of the eccentric pointed load 偏心荷载对各主梁的综合作用When the load is applied on the first girder当荷载作用于第1号梁Note that e=a1 and I1=I5,3.Method based on stiffness tra

9、nsverse connection偏心压力法,3）Theory 原理D.Transverse influence line of loads荷载横向影响线 The load distribution on the girders when load is applied on the k girder当荷载作用于第i号梁上时，各主梁的荷载分布：,a1,P=1,（6）,Specially,when each girder has the same section当各主梁截面尺寸相同时，,（6）,11,3.Method based on stiffness transverse connecti

10、on偏心压力法,4）Example 偏心压力法的计算实例,75,700,75,计算步骤判断采用何种方法计算,3.Method based on stiffness transverse connection偏心压力法,4）Example 偏心压力法的计算实例,75,700,75,计算步骤判断采用何种方法计算绘制横向影响线,-0.200,0.600,480,30,3.Method based on stiffness transverse connection偏心压力法,4）Example 偏心压力法的计算实例,0.575,150,75,700,75,计算步骤判断采用何种方法计算绘制横向影响线按

11、最不利位置布载 汽车荷载,180,180,130,50,0.350,-0.038,0.188,-0.200,0.600,460,30,3.Method based on stiffness transverse connection偏心压力法,4）Example 偏心压力法的计算实例,计算步骤判断采用何种方法计算绘制横向影响线按最不利位置布载计算相应的 荷载横向分布系数,0.575,150,75,700,75,180,180,130,50,0.350,-0.038,0.188,-0.200,460,30,3.Method based on stiffness transverse connec

12、tion偏心压力法,5）Example 偏心压力法的计算实例,75,700,75,横向影响线绘制的技巧1#梁影响线2#梁影响线3#梁影响线,-0.200,0.600,480,30,0.400,0.200,0.000,Review on the Method based on stiffness transverse connection偏心压力法回顾,P,P,L,e,Review on the Method based on stiffness transverse connection偏心压力法回顾,When the load is applied on the k girder当荷载作用于

13、第k号梁(e=ak)：,R1k,R2k,R5k,R3k,R4k,ak,P,Review on the Method based on stiffness transverse connection偏心压力法回顾,R1k,R2k,R5k,R3k,R4k,ak,P,When the load is applied on the k girder当荷载作用于第k号梁(e=ak)：,3.3 Computation of Coefficients of Transverse Distribution of Loads 荷载横向分布计算,4.Summarization on the method 偏心压力

14、法小结,1）基本假设及适用范围2）原理及公式推导3）横向影响线的求法4）荷载布置及横向分布系数计算,3.3 Computation of Coefficients of Transverse Distribution of Loads 荷载横向分布计算,Review of the methods for computing coefficients of transverse distribution of loads 荷载横向分布系数计算方法回顾杠杆原理法 适宜于支点截面处偏心压力法 适宜于跨中截面处,3.3 Computation of Coefficients of Transverse

15、 Distribution of Loads 荷载横向分布计算,7.The Variation of the Coefficients along the span 荷载横向分布系数沿桥跨的变化Supported end 支点处 m0Mid-span 跨中处mc,端横隔板,中横隔板,1/4横隔板,l/4,3.3 Computation of Coefficients of Transverse Distribution of Loads 荷载横向分布计算,7.The Coefficient Variation along the span荷载横向分布系数沿桥跨的变化荷载横向分布系数沿桥跨的变化

16、的几种情况：,mc,m0,m0,l/4,mc,m0,m0,m0 mc,mc,m0,m0,mc,m0,m0,mc m0,边梁,中梁,3.3 Computation of Coefficients of Transverse Distribution of Loads 荷载横向分布计算,荷载横向分布系数沿桥跨的变化的几种情况：,mc,m0,m0,mc,m0,m0,mc,m0,m0,mc,m0,m0,3.4 Computing the internal forces of the main girder 主梁内力计算,恒载内力计算 结构自重 桥面铺装 附属设施重量根据施工的过程决定分别计算不同阶段的

17、恒载,3.4 Computing the internal forces of the main girder 主梁内力计算,2.活载内力计算,m0,mc,Pk,y1,Mc影响线,荷载横向分布系数,Pk,qk,3.4 Computing the internal forces of the main girder 主梁内力计算,2.活载内力计算,mck,Q0影响线,荷载横向分布系数,m0,mc,Pk,qk,a,y1,y2,3.4 Computing the internal forces of the main girder 主梁内力计算,3.内力组合,对于简支梁，最不利组合：,1.2 恒荷载+1.4 汽车荷载+0.8 1.4 人群荷载,3.4 Computing the internal forces of the main girder 主梁内力计算,4.主梁内力计算实例,恒载内力计算 一期恒载、二期恒载集度 恒载内力,活载内力计算 跨中弯矩、剪力 支点剪力,内力组合,