阎奇武(1963-), 男, 博士, 副教授, 主要从事组合结构和装配式结构研究, E-mail:
Yan Qiwu (1963-), PhD, associate professor, main research interests: composite structures and fabricated structures, E-mail:
为研究新型内翻U形外包钢-混凝土组合梁正截面抗弯承载力及其构造要求,以已有内翻U型外包钢-混凝土组合连续试验梁为参照,建立该组合连续梁非线性有限元模型,模拟组合连续梁有限元模型的荷载-跨中挠度曲线,并与相关试验结果对比,验证了该组合梁有限元模型的建模方法和参数选取的合理性与有效性。应用建立的组合连续梁有限元模型,分析了内翻外包钢-混凝土组合梁正截面抗弯承载力的主要影响参数。综合内翻U型外包钢-混凝土组合连续梁正截面抗弯承载力试验和模拟结果,提出采用简化塑性理论计算组合梁正截面抗弯承载力计算时,组合梁正截面抗弯承载力塑性理论计算值应乘0.96的修正系数。0.96倍组合梁正截面抗弯承载力塑性理论计算值与组合梁有限元模型模拟计算值相比较,发现二者十分接近,偏于安全,提出的组合梁正截面抗弯承载力修正简化塑性理论计算值具有足够的准确性和可靠性。
In order to study the normal section bearing capacity and the formation requirements of a novel inverted U-shaped steel-encased concrete composite beam, the nonlinear finite element models of the composite continuous beams have been established based on the existing U-shaped steel-encased concrete composite continuous beams. The load-deflection curve at mid-span of the composite continuous beam finite element model was plotted, and compared with other test results. It proves the rationality and effectiveness of the modeling method and parameter selection of the composite beam finite element models. Using the established finite element model of composite continuous beams, the main influential parameters of normal section bearing capacity of the inverted steel-encased concrete composite beams are analyzed. Based on the test and simulation results of normal section bearing capacity of inverted U-shaped steel-encased concrete composite continuous beams, it is proposed that when the normal section bearing capacity of the composite beam is calculated by the simplified plastic theory, the plastic theoretical calculation value of the normal section bearing capacity of the composite beam should be multiplied by a correction factor of 0.96. Comparing the calculated value of 0.96 times the plastic theoretical calculation value of the normal section bending capacity of the composite beam with the calculated value of the finite element model of the composite beam, the two values are found very close in safe side. The proposed modified simplified plastic theory calculation value of the normal section bending capacity of the composite beam is accurate and reliable enough.
钢-混凝土组合结构在土木工程发展中正扮演着愈加重要的角色,不少学者对外包钢-混凝土组合梁做了许多研究。操礼林等[
鉴于上述优点,新型内翻U形外包钢-混凝土组合梁具有较大的工程应用前景,而文献[
利用ABAQUS建立文献[
两跨组合连续梁及荷载
A two-span composite continuous beam and its load
组合连续梁截面
Composite continuous beam section
钢筋及钢板实测力学性能
Material properties of rebars and steels
钢材类型 | 直径或厚度/mm | 屈服强度/MPa | 极限强度/MPa | 伸长率/% |
钢筋 | 6 | 390 | 625 | 36 |
10 | 380 | 600 | 28 | |
14 | 365 | 580 | 25 | |
钢板 | 3 | 466 | 654 | 16 |
6 | 465 | 660 | 18 |
组合梁有限元模型的混凝土本构模型采用塑性损伤模型,混凝土的单轴受力-应变曲线采用过镇海[
模型中的钢板的本构模型采用弹塑性硬化模型,强度准则采用Mises屈服准则和相关联流动法则,其单轴应力-应变表达式采用Ding等[
U型箱梁与混凝土之间的接触面存在切向和法向作用,其法向采用硬接触,切向采用罚函数,摩擦因子根据刘威[
混凝土和加载板采用八节点减缩积分实体单元C3D8R;内翻U型外包钢采用四节点减缩积分壳单元S4R,沿壳单元的厚度方向采用9个节点的Simpson积分;钢筋采用两节点线性三维桁架单元T3D2;栓钉采用线性梁单元B31。组合两跨连续梁有限元模型见
内翻U型外包钢-混凝土组合两跨连续梁有限元模型
FE model of introsus U-shaped steel-encased concrete composite two-span continuous beam
如
分别对文献[
文献[
组合梁有限元模型极限荷载时的应力云图及其变形与试件试验现场变形
Stress nephogram of finite element model of a composite beam under ultimate load and its deformation and in-situ deformation of a specimen
组合两跨连续梁有限元模型荷载-跨中挠度数值模拟荷载达到弯曲破坏极限荷载时典型的混凝土、钢板、钢筋应力云图与变形见
试件B1、B2、B3试验荷载-挠度曲线见
试件试验荷载-挠度曲线与模拟的对比
Comparison of load-deflection curves between test and simulation
利用建立的组合梁有限元模型对文献[
由
通用屈服弯矩法示意图
Schematic diagram of general yield moment method
试件主要试验结果与数值模拟结果比较
Comparison of test results and simulation results of specimens
No. | Δy/mm | Δny/mm | Δx/mm | Δnx/mm | ||||||||
注: | ||||||||||||
B1 | 094.5 | 100.7 | 6.5 | 278.2 | 298.2 | 7.2 | 7.8 | 8.3 | 5.4 | 63.7 | 59.0 | -7.4 |
B2 | 127.1 | 130.2 | 2.4 | 296.6 | 315.1 | 6.3 | 8.1 | 8.3 | 3.3 | 50.5 | 52.9 | -4.7 |
B3 | 208.0 | 215.9 | 3.8 | 298.2 | 328.0 | 9.9 | 8.6 | 9.4 | 9.3 | 47.4 | 50.2 | -5.9 |
有限元模型B1荷载-挠度荷载特征值点时截面关键点应力应变
Stresses and strains at section key points on load characteristic points of the load-deflection of finite element model B1
荷载特征 | 应力/MPa | 受压混凝土边缘应变 | |||||||||
跨中底钢板 | 中支座底钢板 | 跨中顶钢板 | 中支座顶钢板 | 跨中受拉主筋 | 跨中受压主筋 | 中支座受拉主筋 | 中支座受压主筋 | 跨中 | 中支座 | ||
屈服 | 185.39 | 52.38 | 101.73 | 113.56 | 129.79 | 113.41 | 148.85 | 101.16 | 0.000 757 | 0.000 254 | |
峰值 | 465.00 | 142.10 | 465.03 | 465.01 | 390.15 | 390.74 | 390.19 | 390.24 | 0.003 34 | 0.003 22 |
有限元模型模拟和试验试件的荷载-跨中挠度曲线表明,合理配置钢筋的U型外包内翻组合梁发生弯曲破坏,荷载达到组合梁峰值荷载时,组合梁跨中与中支座截面除中支座底板受压没屈服外,其他钢筋或钢板无论受拉还是受压,都达到其屈服应力,受压的混凝土边缘应变接近或超过混凝土极限压应变0.003 3,受压混凝土应力基本都达到混凝土受压峰值应力,U型外包组合梁正截面承载力可以采用大多数组合梁正截面承载力计算采用的简化塑性理论计算。组合两跨连续梁有限元模型荷载-跨中挠度模拟与梁的试验荷载-跨中挠度变形规律基本一致,说明组合两跨连续梁建模方法及参数选取具有合理性,建立的组合两跨连续梁有限元模型具有满足工程要求的准确性和可靠性。
为了深入研究新型内翻U形外包钢-混凝土组合梁正截面抗弯承载力,采用上述模拟较准确的B1、B2有限元模型,对组合梁正截面抗弯承载力进行参数分析。T形组合梁有限元模型荷载-挠度模拟主要研究参数包括:腹板和翼缘受力纵筋直径、U形外包钢梁厚度、混凝土强度、翼缘尺寸、腹板尺寸、一体式开孔板连接件尺寸及其开孔间距、孔径、贯通钢筋直径、底部栓钉尺寸及间距,组合梁有限元模型荷载-挠度模拟参数见
试件有限元模型正截面抗弯性能分析参数
Parameters of normal section bending performance analysis of specimen finite element models
试件名称 | 变化部分 | 变化参数 | 变化值 |
B1 | 翼缘受力纵筋 | 直径/mm | 06 |
B2 | 10 | ||
B3 | 14 | ||
B2-FBZJ6 | 腹板受力纵筋 | 直径/mm | 06 |
B2-FBZJ10 | 10 | ||
B2-FBZJ14 | 14 | ||
B2-46 | U形外包钢梁 | 侧板/mm |
4 |
B2-56 | 5 | ||
B2-66 | 6 | ||
B2-38 | 8 | ||
B2-39 | 9 | ||
B2-310 | 10 | ||
B2-C40 | 混凝土 | 混凝土轴心抗压强度设计值/(N·mm-2) | 19.1 |
B2-C45 | 21.1 | ||
B2-C60 | 27.5 | ||
B2-C65 | 29.7 | ||
B2-YYG80 | T形混凝土梁翼缘尺寸 | 翼缘高/mm |
080 |
B2-YYG100 | 100 | ||
B2-YYG120 | 120 | ||
B2-YYK660 | 660 | ||
B2-YYK680 | 680 | ||
B2-YYK700 | 700 | ||
B2-FBG140 | T形混凝土梁腹板尺寸 | 腹板高/mm |
140 |
B2-FBG150 | 150 | ||
B2-FBG160 | 160 | ||
B2-FBK110 | 110 | ||
B2-FBK120 | 120 | ||
B2-FBK130 | 130 | ||
B2-PBLB3 | 一体式开孔板连接件尺寸 | 厚度/mm |
3 |
B2-PBLB4 | 4 | ||
B2-PBLB5 | 5 | ||
B2-PBLB6 | 6 | ||
B2-PBLH50 | 50 | ||
B2-PBLH60 | 60 | ||
B2-PBLH70 | 70 | ||
B2-PBLD20 | 20 | ||
B2-PBLD25 | 25 | ||
B2-PBLD30 | 30 | ||
B1-80 | 开孔板连接件 | 开孔板连接件间距/mm | 80 |
B1-120 | 120 | ||
B1-160 | 160 | ||
B2-G6 | 贯通钢筋 | 直径/mm | 6 |
B2-G10 | 10 | ||
B2-G14 | 14 | ||
B2-S160 | 底板栓钉 | 间距/mm |
160 |
B2-S120 | 120 | ||
B2-S80 | 80 | ||
B2-SD10 | 10 | ||
B2-SD13 | 13 | ||
B2-SD16 | 16 | ||
B2-SD19 | 19 | ||
B2-SC70 | 70 | ||
B2-SC60 | 60 | ||
B2-SC50 | 50 |
各参数下组合两跨连续梁有限元模型模拟的跨中荷载-挠度曲线
Load-deflection curves in mid-span simulated by finite element model of composite two-span continuous beams under various parameters
由
保持组合梁模型其他参数不变,不同侧板的厚度和底板厚度对组合梁正截面抗弯承载力的影响如
保持组合梁模型其他参数不变,不同的混凝土强度等级对正截面抗弯承载力的影响如
如
T形组合梁模型保持其他参数不变,仅改变梁腹板尺寸,组合梁有限元模型跨中荷载-挠度曲线模拟结果如
由
组合梁有限元模型开孔板连接件不同开孔间距的荷载-挠度曲线模拟结果如
保持组合梁模型其他参数不变,仅改变组合梁一体式开孔板贯通钢筋直径,其计算结果如
由
综上所述,影响新型内翻U形外包钢-混凝土组合梁正截面抗弯承载力的关键因素为T形梁腹板和翼缘受力纵筋直径、U形外包钢梁厚度、混凝土轴心抗压强度、翼缘高度、腹板高度和宽度。
基于组合梁有限元模型模拟分析与组合梁试验成果,计算内翻U形外包钢-混凝土组合梁正截面抗弯承载力时,可采用简化塑性理论,并假定[
1) 混凝土翼板与内翻U形外包钢之间抗剪连接件的数量足以充分发挥组合梁截面的抗弯能力。
2) 组合梁的应变符合平截面假定。
3) 不考虑开裂后受拉混凝土的作用,混凝土压应力为均匀分布的矩形应力分布,并达到混凝土轴心抗压强度设计值。
4) 根据塑性中和轴的位置,U形外包钢、钢筋可能全部受拉或部分受压部分受拉,但都假定为均匀受力,并达到钢材、钢筋的抗拉或抗压强度设计值。
组合梁配筋截面如
组合梁配筋截面
Reinforcement section of a composite beam
承受正弯矩作用的T形截面塑性中和轴在翼缘内时的计算简图
Calculation Diagram of T-section Bearing Positive Moment with Plastic Neutral Axis in the Flange
承受正弯矩作用的T形截面塑性中和轴在腹部内时的计算简图
Calculation Diagram of T-section Bearing Positive Moment with Plastic Neutral Axis in the Web
承受负弯矩作用的T形截面塑性中和轴在腹部内时的计算简图
Calculation Diagram of T-section Bearing Negative Moment with Plastic Neutral Axis in the Web
承受负弯矩作用的T形截面塑性中和轴在翼缘内时的计算简图
Calculation Diagram of T-section Bearing Negative Moment with Plastic Neutral Axis in the Flange
1) 承受正弯矩作用的组合梁T形截面,塑性中和轴在T形截面翼缘内,且在开孔板上翼缘与混凝土边缘之间,截面计算简图见
则
式中:
2) 承受正弯矩作用的组合梁T形截面,塑性中和轴在T形截面腹板内,如
则
式中:
1) 承受负弯矩作用的组合梁T形截面,塑性中和轴在T形截面腹板内, 如
则
式中:
2) 承受负弯矩作用的组合梁T形截面,塑性中和轴在T形截面翼缘内,如
则
式中:
组合梁正截面抗弯承载力有限元模型模拟值与相应组合梁正截面抗弯承载力简化塑性理论计算值的比较见
正弯矩区T形截面正截面抗弯承载力模拟值与理论值比较
Comparisons between the simulated values and theoretical values of T-section normal section bending capacity bearing positive moment
试件名称 | ||||
注:表格中 | ||||
B1 | 135.89 | 137.50 | 0.99 | 0.97 |
B2 | 156.79 | 160.63 | 0.98 | 0.98 |
B3 | 188.14 | 195.32 | 0.96 | 1.00 |
B2-FBZJ6 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-FBZJ10 | 165.06 | 168.15 | 0.98 | 0.98 |
B2-FBZJ14 | 176.85 | 179.49 | 0.99 | 0.97 |
B2-46 | 169.64 | 183.24 | 0.93 | 1.04 |
B2-56 | 196.05 | 203.44 | 0.96 | 1.00 |
B2-66 | 220.19 | 222.44 | 0.99 | 0.97 |
B2-38 | 166.13 | 184.60 | 0.90 | 1.07 |
B2-39 | 179.17 | 195.77 | 0.92 | 1.05 |
B2-310 | 193.83 | 206.82 | 0.94 | 1.02 |
B2-C40 | 141.69 | 152.52 | 0.93 | 1.03 |
B2-C45 | 143.64 | 154.13 | 0.93 | 1.03 |
B2-C60 | 159.60 | 162.04 | 0.98 | 0.97 |
B2-C65 | 161.22 | 162.97 | 0.98 | 0.97 |
B2-YYG80 | 127.22 | 133.25 | 0.95 | 1.01 |
B2-YYG100 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-YYG120 | 175.94 | 180.34 | 0.98 | 0.98 |
B2-YYK660 | 156.56 | 160.53 | 0.98 | 0.98 |
B2-YYK680 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-YYK700 | 157.71 | 162.18 | 0.97 | 0.99 |
B2-FBG140 | 133.17 | 141.89 | 0.94 | 1.02 |
B2-FBG150 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-FBG160 | 168.02 | 171.95 | 0.98 | 0.98 |
B2-FBK110 | 149.73 | 155.61 | 0.96 | 1.00 |
B2-FBK120 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-FBK130 | 165.29 | 167.95 | 0.98 | 0.98 |
B2-PBLB3 | 215.88 | 220.28 | 0.98 | 0.98 |
B2-PBLB4 | 217.14 | 221.01 | 0.98 | 0.98 |
B2-PBLB5 | 218.95 | 222.74 | 0.98 | 0.98 |
B2-PBLB6 | 220.19 | 222.44 | 0.99 | 0.97 |
B2-PBLH50 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-PBLH60 | 156.08 | 162.79 | 0.96 | 1.00 |
B2-PBLH70 | 154.56 | 163.22 | 0.95 | 1.01 |
B2-PBLD20 | 155.88 | 162.48 | 0.96 | 1.00 |
B2-PBLD25 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-PBLD30 | 154.83 | 161.11 | 0.96 | 1.00 |
B1-80 | 146.10 | 152.97 | 0.96 | 1.01 |
B1-120 | 148.57 | 152.97 | 0.97 | 0.99 |
B1-160 | 147.65 | 152.97 | 0.97 | 0.99 |
B2-G6 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-G10 | 157.65 | 160.63 | 0.98 | 0.98 |
B2-G14 | 157.39 | 160.63 | 0.98 | 0.98 |
B2-S160 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-S120 | 155.03 | 160.63 | 0.97 | 0.99 |
B2-S80 | 157.98 | 160.63 | 0.98 | 0.98 |
B2-SD10 | 154.87 | 160.63 | 0.96 | 1.00 |
B2-SD13 | 155.30 | 160.63 | 0.97 | 0.99 |
B2-SD16 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-SD19 | 157.25 | 160.63 | 0.98 | 0.98 |
B2-SC70 | 156.79 | 160.63 | 0.98 | 0.98 |
B2-SC60 | 156.39 | 160.63 | 0.97 | 0.99 |
B2-SC50 | 154.56 | 160.63 | 0.96 | 1.00 |
负弯矩区T形截面正截面抗弯承载力模拟值与理论值比较
Comparisons between the simulated values and theoretical values of T-section normal section bending capacity bearing negative moment
试件名称 | ||||
B1 | 82.22 | 84.91 | 0.97 | 0.99 |
B2 | 126.42 | 128.07 | 0.99 | 0.97 |
B3 | 173.25 | 176.90 | 0.98 | 0.98 |
B2-FBZJ6 | 126.42 | 128.07 | 0.99 | 0.97 |
B2-FBZJ10 | 127.94 | 129.74 | 0.99 | 0.97 |
B2-FBZJ14 | 129.53 | 131.84 | 0.98 | 0.98 |
B2-46 | 133.41 | 138.77 | 0.96 | 1.00 |
B2-56 | 143.52 | 149.44 | 0.96 | 1.00 |
B2-66 | 152.99 | 160.07 | 0.96 | 1.00 |
B2-38 | 128.56 | 131.80 | 0.98 | 0.98 |
B2-39 | 129.5 | 133.79 | 0.97 | 0.99 |
B2-310 | 131.2 | 135.43 | 0.97 | 0.99 |
B2-C40 | 121.85 | 124.21 | 0.98 | 0.98 |
B2-C45 | 122.33 | 125.46 | 0.98 | 0.98 |
B2-C60 | 126.53 | 128.66 | 0.98 | 0.98 |
B2-C65 | 127.54 | 129.55 | 0.98 | 0.98 |
B2-YYG80 | 121.52 | 119.72 | 1.02 | 0.95 |
B2-YYG100 | 126.42 | 128.07 | 0.99 | 0.97 |
B2-YYG120 | 131.25 | 132.25 | 0.99 | 0.97 |
B2-YYK660 | 126.11 | 128.07 | 0.98 | 0.97 |
B2-YYK680 | 126.42 | 128.07 | 0.99 | 0.97 |
B2-YYK700 | 126.75 | 128.07 | 0.99 | 0.97 |
B2-FBG140 | 114.1 | 119.88 | 0.95 | 1.01 |
B2-FBG150 | 126.42 | 128.07 | 0.99 | 0.97 |
B2-FBG160 | 136.11 | 136.48 | 1.00 | 0.96 |
B2-FBK110 | 119.51 | 125.28 | 0.95 | 1.01 |
B2-FBK120 | 126.42 | 128.07 | 0.99 | 0.97 |
B2-FBK130 | 129.53 | 130.59 | 0.99 | 0.97 |
B2-PBLB3 | 142.72 | 139.38 | 0.98 | 0.98 |
B2-PBLB4 | 147.00 | 146.62 | 1.00 | 0.96 |
B2-PBLB5 | 151.27 | 150.28 | 0.99 | 0.97 |
B2-PBLB6 | 160.07 | 152.99 | 0.96 | 1.00 |
B2-PBLH50 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-PBLH60 | 130.89 | 126.31 | 0.97 | 0.99 |
B2-PBLH70 | 133.70 | 125.89 | 0.94 | 1.02 |
B2-PBLD20 | 132.45 | 127.89 | 0.97 | 0.99 |
B2-PBLD25 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-PBLD30 | 119.64 | 115.35 | 0.96 | 1.00 |
B1-80 | 128.07 | 123.46 | 0.96 | 1.00 |
B1-120 | 128.07 | 125.25 | 0.98 | 0.98 |
B1-160 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-G6 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-G10 | 128.07 | 127.43 | 0.99 | 0.96 |
B2-G14 | 128.07 | 127.56 | 1.00 | 0.96 |
B2-S160 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-S120 | 128.07 | 124.95 | 0.98 | 0.98 |
B2-S80 | 128.07 | 127.41 | 0.99 | 0.97 |
B2-SD10 | 128.07 | 123.85 | 0.97 | 0.99 |
B2-SD13 | 128.07 | 124.25 | 0.97 | 0.99 |
B2-SD16 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-SD19 | 128.07 | 127.98 | 1.00 | 0.96 |
B2-SC70 | 128.07 | 126.42 | 0.99 | 0.97 |
B2-SC60 | 128.07 | 125.98 | 0.98 | 0.98 |
B2-SC50 | 128.07 | 123.99 | 0.97 | 0.99 |
由
T形截面正截面承载力模拟值与理论值的比较
Comparison of the simulated values and theoretical values of T-section normal section bending capacity
由
由上述组合梁T形截面承载力模拟值与计算值的对比分析可见,组合梁正截面抗弯承载力简化塑性理论计算值与相应正截面抗弯承载力的模型模拟值比较接近,但组合梁正截面抗弯承载力简化塑性理论计算值比绝大多数模型模拟值都大,说明组合梁正截面抗弯承载力按简化塑性理论计算时约高估了组合梁正截面抗弯承载力,组合梁达到正截面抗弯承载力极限状态时,靠近组合梁截面中性轴附近的混凝土或钢筋、钢板材料并没有达到完全塑性,有必要进一步修正组合梁T形截面承载力简化塑性理论计算值。
组合梁正截面抗弯承载力可采用简化塑性理论计算,但计算的组合梁正截面抗弯承载力简化塑性理论计算值应乘小于1的修正系数
对于承受正弯矩作用的组合梁T形截面正截面抗弯承载力计算时,由于54个组合梁正弯矩区正截面抗弯承载力有限元模型模拟值与理论计算值的比值平均值为0.967,方差为0.000 38,按具有95%以上的保证率,该组合梁正弯矩区正截面抗弯承载力修正系数应取
对于承受负弯矩作用的组合梁T形截面正截面抗弯承载力计算时,由于54个组合梁负弯矩区正截面抗弯承载力有限元模型模拟值与理论计算值的比值平均值为0.979,方差为0.000 202,按具有95%以上的保证率,该组合梁负弯矩区正截面抗弯承载力修正系数应取
为简化计算,无论承受正弯矩作用还是负弯矩作用,采用简化塑性理论计算组合梁T形截面正截面抗弯承载力时,建议组合梁正截面抗弯承载力塑性理论计算值应统一乘更偏安全的
因此,采用简化塑性理论计算得到组合梁T形截面正截面抗弯承载力简化塑性理论计算值
1) 承受正弯矩作用的组合梁T形截面,塑性中和轴在T形截面翼缘内,且在开孔板上翼缘与混凝土边缘之间时
2) 承受正弯矩作用的组合梁T形截面,塑性中和轴在T形截面腹板内时
采用0.96
1) 承受负弯矩作用的组合梁T形截面,塑性中和轴在T形截面腹板内时
2) 承受负弯矩作用的组合梁T形截面,塑性中和轴在T形截面翼缘内
采用0.96
由于已经通过组合两跨连续梁荷载-跨中挠度试验现象成功验证了建立的组合两跨连续梁有限元模型的可靠性,因而0.96
通过内翻U型外包钢-混凝土组合连续梁试验成果验证了新型内翻U形外包钢-混凝土组合两跨连续梁有限元模型建模方法和参数选取的合理性和正确性,在综合组合梁正截面抗弯承载力的简化塑性理论计算和模型参数模拟成果基础上,提出了新型内翻U形外包钢-混凝土组合梁正截面抗弯承载力计算方法及其构造措施,主要结论如下:
1) 影响组合梁正截面抗弯承载力的关键因素为:受力纵筋、U形外包钢板、混凝土强度、截面形状与尺寸。
2) 新型内翻U形外包钢-混凝土组合梁正截面抗弯承载力可采用简化塑性理论计算,但组合梁达到正截面抗弯承载力极限状态时,靠近组合梁截面中性轴附近的混凝土或钢筋、钢板材料并没有达到完全塑性。
3) 采用简化塑性理论计算组合梁正截面抗弯承载力时,组合梁正截面抗弯承载力塑性理论计算值应乘0.96的修正系数。
4) 当组合梁底部腹板受拉时,底部钢板可设置较少栓钉,外包钢底板栓钉间距宜不小于80 mm或5
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