Journal of Structural Engineering and Geo-Techniques
,
Issue30,Year,
Spring
2023
Conventional reduced beam sections (RBS) maintain their capacity with up to 4% drift angle, after which local buckling at the reduced section significantly reduces their resistance. The use of hybrid-sandwiched reduced beam sections (HS-RBS) in the reduced section of co More
Conventional reduced beam sections (RBS) maintain their capacity with up to 4% drift angle, after which local buckling at the reduced section significantly reduces their resistance. The use of hybrid-sandwiched reduced beam sections (HS-RBS) in the reduced section of conventional RBS beams previously proposed by the authors can increase the energy absorption capacity, allowing the beam to reach 7% drift without losing capacity. The experimental results indicate that placing the HS-RBS in the reduced section of the RBS beam does not disrupt its main role in forming a plastic joint in the reduced section. HS-RBS is comprised of grout, nuts and bolts, and the sandwiching plates. In this system, the bolts and the sandwiching plate enclose the grout and the bolts are placed in the grout on two sides of the beam web in the reduced section to increase the grout's capacity to resist the tensile stresses arising from the web buckling. The sandwiching plate is located in the reduced section on two sides of the flange to enclose the grout and increase the buckling resistance of the flange. This study employed finite element modeling (FEM) to analyse beam bolts with different diameters for different sections of the HS-RBS to obtain the best diameter for each bolt. Moreover, sandwiching plates with different thicknesses were examined to find the best thickness.
Manuscript profile
International Journal of Advanced Structural Engineering
,
Issue1,Year,
Winter
2022
The problem of overcrowding at the junction of the rebars is very significant, particularly for seismic details. Mechanical couplers can, thus offer an appealing solution that eliminates the disadvantages of traditional reinforcement splicing. By identifying the target More
The problem of overcrowding at the junction of the rebars is very significant, particularly for seismic details. Mechanical couplers can, thus offer an appealing solution that eliminates the disadvantages of traditional reinforcement splicing. By identifying the target area for bar failure, the potential area for failure could be modified with this in mind, it is very useful in assessing the position of the reinforced concrete (RC) plastic hinge. In this context, the present study focuses on the numerical and analytical modelling of the experimentally obtained response of Integrated bar (without coupler) and bars with mechanical coupler to tensile uniaxial tests. Simulation results showed agreement with the experimental response in terms of load–elongation curve, Von Mises yield and failure mode .After validating the model, alternative designs (diameter, height and thickness of mechanical couplers and bar) were numerically tested to study the influence of the geometry of the structural system on the failures mechanical coupler. Overall results indicated that the optimum design would be the one with an increased diameter in the thread area of both the bar and the mechanical coupler. For this improved configuration, the load-bearing capacity was Similar to the Integrated bar (without coupler) Cases.
Manuscript profile
Analysis of Structure and Earthquake
,
Issue2,Year,
Summer
2024
استفاده از سیستمهای قاب خمشی فولادی در بین طراحان بسیار رواج دارد، اما یک نقطه ضعف اصلی در این سیستمها، محل تشکیل مفصل پلاستیک در ناحیه اتصال تیر به ستون میباشد. از این رو ایده استفاده از تیرها با مقطع کاهشیافته پیشنهاد مناسبی برای دور ک More
استفاده از سیستمهای قاب خمشی فولادی در بین طراحان بسیار رواج دارد، اما یک نقطه ضعف اصلی در این سیستمها، محل تشکیل مفصل پلاستیک در ناحیه اتصال تیر به ستون میباشد. از این رو ایده استفاده از تیرها با مقطع کاهشیافته پیشنهاد مناسبی برای دور کردن محل تشکیل مفصل پلاستیک از ناحیه اتصال تیر به ستون به ناحیه کاهشیافته تیر میباشد. با استفاده از تیرهای فولادی با مقطع کاهشیافته، یک فیوز شکلپذیر در تیر ایجاد میشود که مانع از انتقال تنشها و کرنشهای غیرارتجاعی به محل اتصال تیر به ستون (در ناحیه جوش) میشود. یکی از مشکلات اصلی در تیرهای فولادی با مقطع کاهشیافته، ایجاد کمانشهای موضعی در ناحیه کاهشیافته تیر میباشد. به تبع این کمانشهای موضعی در بال و جان تیر در ناحیه کاهش یافته، مقاومت این تیرها نسبت به تیرهای معمولی کاهش پیدا میکند. در این مقاله تحلیل اجزای محدود برای تیرهای فولادی با مقاطع مختلف انجام گرفته است تا مشخص گردد در تیرهای فولادی با مقاطع کاهشیافته مختلف درچه میزان دریفت، دچار کمانش موضعی میشوند. کمانشهای محلی در ناحیه کاهشیافته تیرهای فولادی معمولا در مقاطع با ابعاد کوچک در دریفت 3% ایجاد میشود. اما برای مقاطع با ابعاد بزرگتر این کمانشها در دریفتهای پایینتری ایجاد میشود. این کمانشها ابتدا از ناحیه بال تیرهای کاهشیافته مقطع، آغاز و به جان تیر کشیده میشود.