Adjustable deflection testing device suitable for fiber concrete bending toughness test

The invention discloses an adjustable deflection testing device suitable for a bending toughness test of fiber concrete. The adjustable deflection testing device comprises two semi-rectangular vertical supports, two brackets, a plurality of connecting screw rods, two limiting angle steels, a plurality of control screw rods, a plurality of punctual screw rods and a to-be-tested piece, the device can solve the problems that a part used for fixing a midspan deflection test instrument in an existing device mentioned in the specification cannot move flexibly, and the device is not suitable for deflection test instruments of different sizes and specifications. According to the invention, deflection test instruments of different types and specifications can be conveniently and flexibly fixed, the net deflection of the midspan can be accurately measured, the shearing or torsion influence of a sample on the bracket is avoided, and the device can be repeatedly used. The defect that a through hole capable of clamping th