Traffic dynamic effect on road bridge joint

In road engineering, also a well realized bridge expansion joints always creates a discontinuity in the road surface. This unevenness produce very important dynamic load increase due to the moving heavy vehicles. The dynamic component of wheel forces depends on the road pavement profile, the functional characteristics of the vehicle (geometry, mass and stiffness distribution, tire and suspension type, operative speed, etc.) and structural characteristics of the bridge superstructure (span length, geometry, static scheme, natural frequencies and damping). The dynamic actions can produce a general decay of the structure and local breaks near the biggest pavement unevenness for example near the Highway Bridge Expansion Joints (BEJ) and could decrease or cancel the skid resistance between road and tire, with dangerous consequences on traffic safety. Generally, it is recommended to consider the dynamic actions between the vehicle and the road. The definition of these actions is possible by means of the analysis of vertical accelerations measured, for example, on a heavy vehicle axle running on the joint. An innovative approach for solving the problem of dynamic interaction between heavy vehicle and BEJ is presented, taking advantage of the all purpose explicit finite element code LSDyna. The proposed model allows to determine, varying the parameters of the test vehicle (load, geometric dimensions and speed), of the JOINT unevenness dimensions (amplitude and wavelength) and of pavement modulus, the stresses and deformations on JOINT and of each pavement layer due to dynamic actions generated by vehicle motion. The model allows to also determine the accelerations on the vehicle, to verify the Ride Quality of a uneven pavement.