ارائه مدل بهینه طراحی قاب‌های خمشی فولادی مقاوم در برابر زلزله برای بار انفجار سطحی

ساخت سازه‌های مقاوم در برابر بارهای انفجاری و ارتعاش شدید بسیار ضروری می‌باشد. سازه‌ها آسیب‌پذیری‌های گوناگونی در برابر بارهای وارده دارند. یکی از موارد آسیب‌پذیری سازه‌ها در برابر انفجار، عدم طراحی صحیح سیستم‌های سازه‌ای آنها می‌باشد. در این پژوهش به ارائه مدل بهینه طراحی سیستم سازه‌های قاب خمشی فولادی در برابر انفجار به روش طراحی بر اساس عملکرد پرداخته شده است. بدین‌منظور ابتدا قاب‌های دو بعدی 4، 5، 6، 7 و 8 طبقه تحت بارگذاری لرزه‌ای برای سطوح عملکرد io، ls و cp بر اساس آیین‌نامه fema356 طراحی گردیده‌اند، سپس قاب‌های مذکور به‌عنوان طرح اولیه تحت بار انفجاری و بر اساس ملاحظات آیین‌نامه ufc3-340-02 و برای سطوح عملکرد فوق‌الذکر باز طراحی گردیدند. نتایج نشان می‌دهد سازه‌های طراحی شده در برابر بارهای لرزه‌ای، رفتار مناسبی در برابر بارهای انفجاری از خود نشان نمی‌دهند و به‌منظور تامین سطوح عملکرد قاب‌ها در برابر بار انفجاری لازم است از مقاطع قوی‌تری استفاده گردد. همچنین در این تحقیق مشاهده گردید با افزایش تعداد طبقات قاب‌ها، مقادیر پارامترهای سازه‌ای قاب‌ها در برابر بار لرزه‌ای و انفجار همگرا می‌شوند.

Optimized Model Design of Earthquake Resistant Bending Frames for Surface Blast Load

The construction of resistant structures against blast loads and vibration is essential. Structures are vulnerable to the external loads in different areas. The initial purpose of designing against blast loads include life safety and the prevention of progressive, collapse based on economic considerations. Structures with these qualities are of great importance and should be protected against explosion. Structures with sensitive and expensive equipment.  Structures with longterm guidance role. Structures that cause disruption when they are destroyed. The clear understanding of any occurrence and its consequences are required in order to provide an assessment. The literature review of designing steel frame structures against explosion is evaluated in the next part. Bogosian et al. [1] have modeled the blast load (3001000 kips) on a structure, and in their result, there is a graph that shows the relation between the chance of occurring an event with weight and the distance of explosive materials. Liew [2] have modeled a five floors steel frame against blast and fire loads. The study on the columns of the structure has shown that local inelastic buckling in critical sections will occur in high strain rates. Izadifar et al. [3] have evaluated the effects of ductility on the behavior of steel frames against explosion. The graph of force against displacement has been drawn and the parameters of ductility has been studied.  An eightfloor steel frame, which has been designed for service load (live and dead load) was evaluated under explosion by Urgessa and Arciszewski [4]. The results of the research show that the joints with side plates exhibit a better behavior than the conventional joints when blasting. They also behave more efficiently than conventional joints because of the use of these joints to move the plastic hinge into the beam. By comparing the behavior of similar joints with differences in the thickness of the bonding sheet, it was shown that doubling the thickness of the bonding sheet reduces the inplane displacement. Inappropriate design is the main reason for the vulnerability of these structures. The optimal model for performancebased design of steel framework structures resistant to explosion is provided in this study. For the purpose of the study, the authors assessed the three performance levels of IO, LS, and CP. The intended system for structures is the steel bending frame. In the first step, the structures are designed against seismic load for three levels of performance. In the second step, the structures were redesigned against the blast load. In order to investigate the behavior of structures, the following parameters were investigated.  Weight of structural materials used Assessment of the designed frames has shown that the weight of structural materials consumed by the specimens against seismic load is less than the weight of structural materials consumed against the blast load.  Examine the horizontal displacement of the roofs of the floors According to the results, the horizontal displacement values of the roofs in the frames are lower than the seismic load compared to the explosive load. Check the absolute acceleration of the roofs of the frames The results show that in designing the frames against the seismic and explosive loads, the absolute acceleration of the roofs is reduced from IO to CP level. Also with respect to the amount of explosive and its distance to the frames and the amount of seismic load, it is observed that as the number of floors increases, the absolute acceleration of the roof of the frames is closer to each other under seismic load and explosive load. References Bogosian, D.D., Dunn, B.W., and Chrostowski, J.D. (1991) Blast analysis of complex structures using physicsbased fastrunning models. Computers and Structures, 72(1), 8192. Liew, J.Y.R. (2008) Survivability of steel frame structures subject to blast and fire. Journal of Constructional Steel Research, 64, 854866. Izadifar, R.A. and Maheri, M.R. (2010) Ductility effects on the behavior of steel structures under blast loading. International Journal of Science and Technology. Transaction B: Engineering. 34(B1), 4962. Urgessa, G.S. and Arciszewski, T. (2011) Blast response comparison of multiple steel frame connections. Finite Elements in Analysis and Design, 47(7), 668675.