Meaning
Mechanical load transfer evaluation in concrete pavement systems determines the effectiveness of steel bars in distributing vehicle weights across adjacent slabs. High dowel shear efficiency reduces the stress experienced by the slab edges and prevents the formation of cracks under heavy traffic loads. This metric represents the ratio of deflection at the loaded side to the deflection at the unloaded side.
Efficiency Ratio
Testing involves applying a known vertical force near a joint and measuring the resulting displacement on both sides of the gap.
Load Distribution
Steel dowels must be positioned accurately at the mid depth of the concrete to ensure they pick up the shear force effectively. Misaligned bars create localized stresses that spall the concrete or lock the joint against thermal expansion. If the bond between the steel and the concrete fails, the dowel shear efficiency drops and the slabs begin to move independently.
Laboratory tests using cyclic loads verify the long term performance of different bar coatings and diameters. Engineers use these values to predict the number of heavy axles the joint can withstand before the subbase erodes.
Fatigue Limit
Repeated wheel passages cause the dowel to loosen slightly over years of service. A reduction in transfer capacity increases the risk of slab faulting and subsequent surface failure.
