This paper deals with behavior of timber-concrete composite structures with mechanical connection systems. The paper is focused to two different connection systems: using dowel-type fasteners and using special surface connector. Analytical model of dowel-type connection system is based on modification of Johansen´s equations valid for timber to timber connections. Behavior of connection system with special surface connector is evaluated by experiments and numerical simulations. The paper deals also with the evaluation of structural timber and the determination of the performance of structural timber elements.