新型装配式UHPC连接护栏构造优化分析

Analysis on Structural Optimization of New Prefabricated UHPC Connected Guardrails

摘要:

针对高速公路桥梁防护需求，提出一种兼具高强度与缓冲性能的预制装配式组合护栏，融合刚性护栏高承载与半刚性护栏吸能变形特性。基于LS-DYNA建立护栏—桥面板精细化有限元模型，模拟SS级台车碰撞，分析后浇材料强度、槽口形状尺寸及纵向连接钢筋参数对防护性能的影响。结果表明：采用100 MPa UHPC后浇材料时，护栏位移峰值降低18.6%，残余位移减少39%；250 mm×250 mm梯形槽口在材料用量与力学性能间较优；纵向连接采用600 mm、?16 mm 及以上HRB400钢筋时，护栏与桥面板严重损伤单元比例可分别控制在11.4%和8.1%以下。优化方案可提升连接可靠性与整体防护性能，并兼顾施工效率与经济性。

Abstract:

To address the protection requirements of expressway bridges, a prefabricated assembled composite guardrail with both high strength and buffering capacity is proposed, which integrates the high load-bearing capacity of rigid guardrails with the energy-absorbing deformation characteristics of semi-rigid guardrails. A refined guardrail-bridge deck finite element model is established on LS-DYNA to simulate the collision of SS-class trolleys and analyze the effects of post-cast material strength, slot geometry and size, and longitudinal connecting reinforcement parameters on protective performance. The results indicate that the use of 100 MPa UHPC post-cast material can reduce the peak displacement and residual displacement of the guardrails by 18.6% and 39%, respectively. A trapezoidal slot with dimensions of 250 mm × 250 mm achieves a favorable balance between material consumption and mechanical performance. When 600 mm, ?16 mm and above HRB400 steel bars are used for longitudinal connection, the proportion of severely damaged units between the guardrail and the bridge deck can be controlled below 11.4% and 8.1% respectively. The optimized scheme can improve the connection reliability and overall protective performance while considering the construction efficiency and economic benefits.