دانلود رایگان مقاله انگلیسی اتصال برشی نوع خرپا برای ستون های کامپوزیتی بتنی فولادی - الزویر 2018

abstract

Shear connectors are important in composite steel-concrete beams. This work presents a new connector, named truss-type shear connector. This connector is an alternative to replace stud bolt in special situation. The connector’s geometry was conceived aiming at low cost, easy execution, high resistance, and efficiency concerning slipping and uplift. Six specimens were constructed for push-out tests comparing this alternative connector with stud bolts. The behavior of the specimens was investigated for collapse, slipping and uplift. Experimental results were compared against numerical FE simulation showing good agreement and providing a global view of the truss-type shear connector behavior and its viability.

6. Conclusions

In this paper a new and efficient alternative connector named Truss Type shear connector, or TT-12.5 for steel-concrete composite beams was presented. TT-12.5 was conceived from 1/2” (12.5 mm) steel bars and its cross section areas is 12% less than the Stud Bolt connectors with 19.0 mm diameter (SB-19.0). Experimental push-out tests of TT-12.5 and SB-19.0 connectors were conducted. Such tests registered the load vs. slip and load vs. uplift of each specimen showing the load capacity and ductility of each connector tested. The tests followed the provisions given on the European Standard EN 1994-1-1:2004 [5]. From the push-out tests, the following observations were taken: The ultimate resistance for TT12.5 specimens is 1553.14 kN on average (or 194.14 kN per conector), against an average of 997,0 kN for SB-19.0 (or 124,63 kN per conector). The calculation of design resistance for each shear connector (PRd), according to European Standard EN 1994-1-1:2004 [5], led to PRd = 62.45 kN per SB-19.0 and PRd = 104.50 kN per TT12.5. The push-out tests allowed the classification of both types of connectors as flexible. TT-12.5 shows good plastic deformation behavior at rupture. There is also a better stress distribution for TT-12.5 connectors as there are two cross section legs compared to one cross section for SB-19.0. Given the results obtained from Up80/d80 ratio, SB-19.0 and TT-12.5 meet the criteria of European Standard EN 1994-1-1:2004 [5], with Up80/d80 ratio 50%. The TT-12.5 connector presented rupture by tension at the end of one of its leg. The weld length adopted at the end of the TT-12.5 legs was enough to resist the applied loads. Welding can be performed with usual electrodes and welding machines, without the need of specific equipment as required for SB-19.0 connector usage. TT12.5 connectors can be supplied already folded in the triangular shape and ready for direct application on the steel I-beam flange of a composite steel-concrete structure. The TT-12.5 connector developed in this research may be an alternative for use in composite steel-concrete beams. The material to manufacture TT12.5 connector can be easily found and its manufacturing and installation are simple. TT-12.5 connector can be used when stud bolts installation is not possible, economically feasible, or when the appropriate equipment for SB-19.0 application is not available.