Behavior of Smart Reinforced Concrete Beam Column Joints Under Monotonic and Repeated Loading

Abstract

ABSTRACT Using the super elastic materials in structures design is becoming apparent in the research feild because of their rare ability in sensing the around effect and reacting against the mechanical and thermal react. The major intent in this research is designing smart reinforced beam column joints by Shape Memory Alloy (SMA) bars. The suggested systems use the Pseudo Elastic (PE) react of the SMA as reinforcement after being subjected to monotonic and repeated load. The behaviors of systems were explored experimentally and validated by using finite element simulation. At first stage, the design of reinforced steel dual interior beam column joint was managed and checked by using experimental test on large-scaled joints. The design of the reinforced joints by utilizing SMA bars (50% of the flexural reinforcement) was conducted then , the experimental test of the joint specimens was carried out to inspect the transfer of the forces. Also, the mechanical steel couplers used to make strong anchorage for the SMA bars in the connection area. The experimental tests of the large-scaled SMA joints showed their better performance comparing to the ordinary one in the term of absorbed energy. In order to estimate load-displacement relationships of these specimens in third stage of this study , analytical models were developed. a parametric comparision study of specimens reinforced by SMA was carried out. It contained a variance in percentage of the SMA in flexural reinforcement (25%, 50%, 75%) of the total flexural reinforcement, and using II various values of the compressive strength had a clear effect on the ultimate load and the ultimate displacement of the specimens . the results shows increasing the the ductility of SMA specimens about (52%) under monotonic loading and decreasing about (21.5%) under repeated loading, also there is decreasing in ultimate load by using SMA bars about (12.8%) in case of monotonic loading and (10.2%) in case of repeated loading. And the absorbed energy increased by using SMA about (34.26%) from the joint reinforced by steel bar and deflection increased about (63.5%) under monotonic load and (46.25%) under repeated loading from the joint reinforced by steel bars, For the numerical analysis the results shows that The ultimate load decreased by using SMA bars in (25%, 50%, 75% ) of total flexural reinforcement about (5, 16, 47 %) respectively, in case of monotonic loading and 20, 10, 9 %) respectively in case of repeated loading, the deflection is increasing by using SMA in (25%, 50%, 75% ) percentage of total flexural reinforcement about (3, 8, 27%) respectively, in case of monotonic loading and (17, 31, 59 %) respectively in case of repeated loading. The ultimate load of 42 MPa specimens decreased by using SMA bars 50% percent of total flexural reinforcement in case of using (28)MPa compressive strength about (12%) but it increased in case of using 65 MPa in about 19%, in case of monotonic loading and it decrease about (5%) for 28 MPa and it increased about (5%) for 65 MPa respectively in case of repeated load.