高原高寒地区“上”形钢-混凝土组合梁的竖向温度梯度模式
Vertical temperature gradient patterns of 上-shaped steel-concrete composite girder in arctic-alpine plateau region

以青海省海黄大桥为工程背景,建立了考虑气象参数的组合梁温度场有限元分析模型,采用实桥测试数据对模型进行了验证; 分析了“上”形组合梁四季竖向温度分布,给出了升温和降温时竖向温度梯度简化模式,研究了太阳辐射强度、气温和风速等气象参数对温差的影响规律,采用极值统计方法给出了50年一遇气象参数代表值下不同沥青混凝土铺装厚度的“上”形组合梁最不利竖向温度梯度模式。研究结果表明:在日照升温和夜间降温过程中,组合梁竖向温度梯度模式不同; 升温过程中最大温差出现在14:00,温度梯度模式可简化为“顶部5次抛物线”加“底部折线”的形式,顶部温差受沥青混凝土铺装厚度影响较大,当铺装厚度分别为0、50、100、150 mm时,顶部温差极大值分别为23.8 ℃、31.7 ℃、24.1 ℃、17.4 ℃,底部温差极大值可取5.1 ℃; 降温过程中最大温差出现在2:00,温度梯度模式可简化为“顶部双折线”与“底部等温段”的形式,顶部温差受沥青混凝土铺装厚度影响较大,当铺装厚度分别为0、50、100、150 mm时,顶部温差极小值分别为-12.2 ℃、-8.2 ℃、-5.0 ℃、-2.9 ℃,底部温差极小值可取-16.4 ℃; “上”形组合梁竖向温度梯度受气象参数的影响,温度与太阳日辐射总量和气温基本呈线性关系,而与风速表现出非线性关系; “上”形组合梁升温梯度模式与美国AASHTO规范接近,但顶部温差取值较美国AASHTO规范高1.7 ℃,降温梯度模式与欧洲规范接近,但底部温差较欧洲规范低8.4 ℃,故本文给出的温度梯度模式更为不利。
Taking Haihuang Bridge in Qinghai Province as engineering background, a finite element analytical model of composite girder temperature field was established under considering meteorological parameters and verified by the field test data of bridge. The vertical temperature distributions of 上-shaped composite girder in all seasons were analyzed, and the simplified patterns of vertical temperature gradient during warming and cooling were proposed. The influence rules of meteorological parameters such as solar radiation intensity, temperature and wind velocity on the temperature difference were studied. Based on the extreme statistic method, the worst vertical temperature gradient patterns of 上-shaped composite girders with different asphalt concrete laying thicknesses under the meteorological parameter represent values in 50-year return period were calculated. Analysis result shows that during warming in day and cooling at night, the vertical temperature gradient patterns of composite girder are different. The maximum temperature difference during warming takes place at 14:00, and the temperature gradient pattern can be simplified as the linetype with 5-parabola at the top and broken line at the bottom. The temperature difference at the top is greatly influenced by the laying thickness of asphalt concrete. When the laying thicknesses are 0, 50, 100, 150 mm, respectively, the maximum temperature differences at the top are 23.8 ℃, 31.7 ℃, 24.1 ℃ and 17.4 ℃, respectively. The maximum temperature difference at the bottom is 5.1 ℃. The minimum temperature difference during cooling takes place at 2:00, and the temperature gradient pattern can be simplified as the linetype with double broken line at the top and isothermal section at the bottom. The temperature difference at the top is greatly influenced by the laying thickness of asphalt concrete. When the laying thicknesses are 0, 50, 100, 150 mm,