Behaviour of functionally graded reinforced-concrete beams under cyclic loading

Tijekom zadnjih deset godina primjenjuje se slojevito mikroarmiranje kao nova metoda za proizvodnju armiranobetonskih elemenata. U radu su prikazani rezultati ispitivanja svojstava slojevito mikroarmiranih betonskih greda izloženih djelovanju cikličnog opterećenja. Za pripremu uzoraka primijenjena su čelična i polipropilenska vlakna. Betonske grede s potpunim kompozitnim djelovanjem ojačane su sa 0,5 do 2 % čeličnih vlakana, a slojevito mikroarmnirane grede sadrže 1,3 % čeličnih vlakana. Dobiveni rezultati pokazuju da se primjenom slojevitog mikroarmiranja betona povećava disipacija energije uslijed cikličkog opterećenjaOver the past decade, the functional grading has been applied as a new method for the manufacturing of reinforced-concrete elements. The objective of this investigation is to evaluate performance of the functionally graded reinforced-concrete beams exposed to cyclic loading. The steel and polypropylene fibres are used for the preparation of samples. Concrete beams with full composite action are strengthened with 0.5 to 2 % of steel fibres, and functionally graded RC beams contain 1.3 % of steel fibres. The use of the functionally graded method to reinforce concrete increases the dissipated energy due to the applied cyclic loading

The Effects of Heat on the Cyclic Behavior of Retrofitted Concrete Columns (by Steel Plates and CFRP)

In this research, in addition to ensuring the accuracy of the numerical simulations, a 3D reinforced concrete column is numerically modeled in three conditions, including a non-retrofitted state, as well as two states retrofitted with steel plates and CFRP. The coupled temperature-displacement analysis of these columns is conducted under cyclic lateral loading in various heat levels, and the effects of both the retrofits and heat on the cyclic lateral behavior of the columns are studied and compared. According to the results of the study, with temperature rise, both lateral forces and energies increase in the non-retrofitted column, the column retrofitted with steel plates, and the column retrofitted with FRP. This is even more significant at 500°C, particularly in retrofitted columns with steel plates. Besides, retrofitting the columns with steel plates (compared to FRP plates) causes a more substantial increase in the heat sensitivity of the column during cyclic lateral loading