Experimental Study On Impact Resistance Of Steel Stranded Cable Drop-Off Beam Protection Device

As a connecting structure facility to prevent the bridge from falling beam,the stranded cable type anti-falling beam device is highly valued and widely used in countries and regions where earthquakes are frequent.The stranded cable type anti-falling beam device can effectively reduce the relative displacement between the upper and lower structure of the bridge caused by the ground shaking load,thus avoiding the occurrence of bridge falling beam damage and ensuring the smooth implementation of earthquake relief work.At present,the research and development of our anti-fallen girder device is still in the imitation stage,and the existing steel stranded cable type anti-fallen girder device lacks impact resistance research.The impact resistance of the steel stranded cable fall protection device mainly depends on the mechanical properties of the steel stranded cable,and the research of the steel stranded cable at this stage is still focused on the static properties of the cable,and the research on the steel stranded cable at home and abroad is extremely limited.Therefore,this paper conducts theoretical analysis,finite element simulation and static and dynamic test research on stranded wire ties to provide reference for the development and upgrading of stranded wire ties type anti-fall beam device and its promotion and application.The main research contents and the results obtained in this paper are as follows:(1)The force analysis of steel stranded cable anchorage system.Based on the previous research,a brief theoretical analysis of the anchorage system of the steel stranded cable was conducted;a cylindrical uniaxial compressive test was conducted on the cold cast body according to the specification,and the basic mechanical property parameters of each type of cold cast body were obtained,and the cold cast body type was analyzed and determined;a finite element model of the steel stranded cable was established with the obtained material mechanical property parameters and the validity of the model was verified by static load test data,and a detailed analysis of the The stresses of the anchor,cold cast body and steel strand were analyzed in detail.(2)Axial tensile static load test study of stranded steel cable.Based on the test results,we analyzed the anchorage efficiency,ultimate bearing capacity,displacement,strain on the outer surface of the anchorage and strain on the strand,and studied the damage pattern,damage mechanism and stress performance of the strand under static load.(3)The impact resistance of stranded steel cables was investigated.The impact force,displacement and strain time curves were measured and analyzed,the static and dynamic test results were compared,the impact resistance of stranded steel cables was studied,and the impact damage mechanism of stranded steel cables was clarified.(4)The strain of steel strand is accurately measured by embedded multi-point fiber grating sensor,and the stress distribution law of steel strand in the anchored section and the nonuniformity of stress distribution of steel strand in the free section are revealed under static and dynamic loading.In summary,this paper presents a systematic study of the stranded wire ties in stranded wire anti-fall beam devices,revealing the damage pattern,damage mechanism and mechanical properties of stranded wire ties under static and impact loads,and promoting the development and practical engineering applications of stranded wire ties anti-fall beam devices.