Research On The Force Transmission Mechanism Of Cable-pylon Composite Anchor Structure With Steel Anchor Beam And Steel Corbel

As a new type of cable-tower anchorage structure,steel anchor beam-steel corbel composite cable-tower anchorage structure has obvious advantages in mechanical performance,but its plate structure is complex,and its force transmission mechanism is different from the existing composite cable-tower anchor structure,so the existing research is not enough to describe this new form of anchorage.Based on the Yangmeizhou Bridge,the stress distribution and cable force transfer law of the steel anchor beam-steel corbel composite cable tower anchorage structure under the dead load of the completed bridge are studied by using the finite element software numerical simulation method,and the structure and stress characteristics of different cable tower anchorage structures are compared.The influence of different connection modes and different load combinations on the anchorage structure of steel anchor beam-steel bracket composite cable tower is explored,and the specific research contents and conclusions are as follows:(1)The structural characteristics and mechanical properties of different structural forms of the pylon anchorage structure are compared and analyzed,and the finite element numerical simulation method is used to carry out the mechanical research of the steel anchor beam-steel corbel composite pylon anchorage structure according to the different connection modes of the steel anchor beam and steel corbel.The results show that the steel anchor beam-steel corbel composite anchorage structure has obvious advantages compared with the hoop prestressed anchorage structure and the steel anchor beamconcrete corbel composite anchorage structure in terms of the mechanical properties of the anchorage structure.Taking the peak stress of steel anchor beam and steel corbel as well as the main tensile stress of cable tower as the judgment standard,it is most reasonable to set the sliding connection mode on the side with larger horizontal cable force,which can maximize the performance of steel anchor beam and reduce the tensile stress of cable tower.(2)The typical anchorage segment of the pylon is selected,and the elastic-plastic finite element numerical analysis method is used to establish a refined local finite element model to analyze the stress state and force transmission mechanism of each component of the steel anchor beam-steel bracket composite anchorage structure of the pylon under the cable force of the bridge.The results show that the high stress area mainly appears at the welding seams of the plates,and the stress concentrates at the rear end of the welding seams of the plates along the cable force direction.In each plate of the steel anchor box,the horizontal component force of the cable is mainly transmitted to the steel anchor beam through the rear bearing plate N5,the upper bearing plate N6 and the anchor box side plate N8,accounting for 85% of the total horizontal component force transmitted by each plate.The vertical component force of the cable is mainly transmitted to the steel bracket through the upper bearing plate N6,the anchor box side plate N8 and the stiffening plate N12,accounting for 75% of the total vertical component force transmitted by each plate.The steel anchor beam bears all the horizontal component force of the cable balance,and the side plate of the anchor beam is the main force bearing plate.The vertical component force of the cable is almost borne by the steel bracket on the corresponding side,and the proportion of the vertical force transmitted by the outer web on the side of the side span is slightly higher than that transmitted by the inner web,while the opposite is true on the side of the middle span.Most of the vertical shear force in the anchorage zone is transmitted through the weld stud group,and the vertical force transmitted by the weld stud group at the side of the side span accounts for 79%,and that at the middle span side accounts for 85%.(3)Based on the elastic-plastic finite element model of the typical anchorage segment of the pylon,by changing the cable angle,the stress distribution of each component is compared,and the change law of stress distribution,cable force transmission and cable force distribution among each plate is observed,so as to study the force transmission law of the anchorage structure of the steel anchor beam-steel corbel composite pylon under different load combinations.The results show that the change of cable angle has little effect on the peak stress of the steel anchor box,but the distribution ratio of cable force transmission among the plates changes greatly.With the increase of cable angle coefficient,the peak stress of the steel anchor beam decreases,and the proportion of bearing the horizontal force of the cable increases.When the cable angle coefficient exceeds a certain limit,the steel anchor beam bears all the horizontal force of the cable balance.With the increase of the angle coefficient of the cable,the maximum stress of the steel bracket member is controlled by the horizontal force instead of the vertical force,and the position of the maximum stress point is also changed,and the proportion of the web to transmit the vertical force is reduced,while the proportion of the roof to transmit the vertical force is increased.The principal tensile stress on the outer surface of the end wall of the main tower decreases with the increase of the angle coefficient of the cable,and the location of the maximum principal tensile stress gradually moves down from the lower edge of the corbel web,and the stress distribution gradually becomes gentle,which indicates that the increase of the angle coefficient of the cable is beneficial to the end wall of the main tower.