Theory of the four point dynamic bending test : part I

Contains background, theory and interpretation procedures of the four point dynamic bending test. This test is used for the investigation of pavement material properties, such as stiffness modulus and fatigue characteristics. An overview of the equations which govern the interpretation of the measurements is given. In principle, the equations are derived for the four point dynamic test, but the theory can easily be extended to the three point dynamic test, which has the same geometrics. The following items are discussed: general theory for the bending of a rectangular beam; static bending; dynamic bending of an elastic beam; dynamic bending of a visco-elastic beam; concentrated masses at the two inner clamps; influence of the overhanging beam ends on the deflection for an elastic and a visco-elastic beam; advised equations for the backcalculations procedure.