主桁倾角对倒梯形钢桁梁气动特性的影响分析

针对主桁倾角变化对倒梯形钢桁梁气动特性有较大影响的问题，以某公铁两用连续钢桁梁为例，针对不同的主桁倾角，采用计算流体力学(CFD)的方法建立简化的三维分析模型，对钢桁梁节段进行风场模拟，分析不同主桁倾角下的钢桁梁断面静风气动力系数、涡振性能以及流场特性的差异。结果表明：升力系数和力矩系数受主桁倾角变化影响明显，主桁倾角为10°时，钢桁梁的升力系数较优，此时钢桁梁承受较小的竖向风荷载；主桁倾角为0°时，钢桁梁的力矩系数较优，此时钢桁梁承受较小的扭转风荷载；主桁倾角对钢桁梁在0°和6°风攻角条件下的涡激性能影响明显，涡振性能在主桁倾角为2.5°和5°时较优；随着主桁倾角的增大，钢桁梁内部风速存在的减速现象减弱，有利于内部行车稳定；主桁倾角的变化对湍动能的分布影响明显，随着主桁倾角的增大，钢桁梁内部湍动能的增大效果减弱，而钢桁梁背风侧湍动能的增大效果加强；通过综合对比多类气动特性，主桁倾角为5°的钢桁梁的气动特性较优。研究得出了主桁倾角变化对倒梯形钢桁梁主梁气动特性和空间流场特性的影响规律，可为后续钢桁梁的抗风设计提供参考。

Analysis of the influence of maintruss inclination angle on the aerodynamic characteristics of inverted trapezoidal steel joists

Aiming at the problem that the change of the inclination angle of the main truss has a great influence on the aerodynamic characteristics of inverted trapezoidal steel trusses，taking a public-rail continuous steel truss as an example, the effect of main truss inclination on the aerodynamic characteristics of inverted trapezoidal steel truss was investigated. A simplified three-dimensional analysis model was established by using computational fluid dynamics (CFD) method for different main truss inclination angles to simulate the wind field of main turss sections with different main truss inclination angles. The differences of static wind aerodynamic coefficient, vortex vibration performance and flow field characteristics of main truss sections with different main truss inclination angles were analyzed. The results show that the lift and moment coefficients are significantly influenced by the change of main truss inclination, the lift coefficient of the steel truss is better when the inclination angle of the main truss is 10°, at this time the steel truss is subjected to smaller vertical wind load, and the moment coefficient of the steel joist is better when the inclination angle of the main truss is 0°, at this time the steel truss is subjected to smaller torsional wind load; the main truss inclination angle has a significant effect on its vortex excitation performance under 0° and 6° wind angle of attack conditions, and the vortex vibration performance is better at the main truss inclination angles of 25° and 5°;the deceleration phenomenon of wind velocity inside the steel truss decreases with the increase of main truss inclination, it contributes to internal traffic stabilization; the change of main truss inclination has obvious effect on the distribution of turbulent kinetic energy, the effect of increase of turbulent kinetic energy inside the steel truss decreases with the increase of main truss inclination and the effect of increase of turbulent kinetic energy on the leeward side of the steel truss strengthens. By comprehensively comparing multiple types of aerodynamic properties, the aerodynamic characteristics of steel trusses with main truss inclination angles of 5° are better. The influence of the change of main truss inclination angle on the aerodynamic characteristics and spatial flow field characteristics of inverted trapezoidal steel truss can provide a reference for the subsequent wind-resistant design of steel truss.