ارزیابی عملکرد لرزه‌ای سازه‌های قاب محیطی ترکیبی دارای اتصالات نیمه‌صلب با تمرکز بر پیاده‌سازی مفاهیم تحلیلی تاب‌آوری

سازه قاب خمشی فولادی با چیدمان و ساختارهای ترکیبی مختلف می تواند به‌عنوان اسکلت مقاوم با قابلیت میرا نمودن انرژی ناشی از بارگذاری‌های دینامیکی به کار برده شود. این اسکلت مقاوم نیز حاوی چیدمان های مختلف اتصالات صلب و نیمه‌صلب است. هدف از این پژوهش، ارزیابی مشخصات عملکرد لرزه ای دو سازه قاب خمشی محیطی دسته شده با پیکربندی 10 و 20 طبقه است. پیکربندی هر دو اسکلت مقاوم نیز در دو حالت دارای چیدمان اتصالات صلب کامل و نیز حاوی آرایش ترکیبی از اتصالات صلب و نیمه‌صلب با گیرداری 80 درصد می باشد. بررسی های صورت گرفته در این پژوهش، متاثر از وجود اثرات پالس و اسپایک های نیرومند سرعت در تاریخچه زمانی رکوردهای سه مولفه‌ای انتخابی است. رفتار و پارامتر های پاسخ لرزه ای سازه های مطالعاتی با انجام و ارزیابی نتایج تحلیل های دینامیکی فزاینده (ida) و دینامیکی غیرخطی تاریخچه زمانی (ntha) بررسی شده است. ارزیابی های مقایسه ای بر روی تغییرات پارامتر تغییر مکان جانبی نسبی طبقات (drift)، تدوین و ساختارسازی نمودار های شکنندگی و محاسبه شاخص استحکام تاب‌آوری لرزه ای (تاب‌آوری سخت) صورت گرفته است. آورده های محاسباتی و نتایج حاصله گویای آن است که حاکمیت اصل ستون قوی-تیر ضعیف، همراه با رعایت مشخصه رفتار پیچشی سخت برای طرح لرزه‌ای می‌تواند سبب تقارب و نزدیکی قابل‌توجه میان پارامترهای پاسخ غیرخطی و شاخص تاب‌آوری اسکلت های قاب-پایه با چیدمان های اتصالات صلب و نیمه‌صلب گردد. همچنین ملاحظه شد که لحاظ نمودن نکات یاد شده، تاثیر به نسبت یکسانی در برقرار ماندن پایداری سازه و جلوگیری از وقوع وضعیت فروریزش تحت اثر جنبش های ضربه‌ای زمین در هنگام زلزله‌های نیرومند دارد.

evaluation of seismic performance of hybrid framed tube structures with semi-rigid connections focusing on the implementation of analytical concepts of resilience

steel moment frame structures with different layouts and composite configurations can be used as resistant systems with the ability to dampen the energy resulting from dynamic loads. this resistant system also contains different layouts of rigid and semi-rigid connections. the primary objective of the present study is to evaluate the seismic performance characteristics and nonlinear dynamic behavior of two bundled tube structures with the configurations of 10 and 20 stories. both resistant skeletons were prepared in two different modes, which include a fully rigid connections arrangement and also contain a combination of rigid and semi-rigid connections with 80% fixity.the investigations carried out in this study are influenced by the effects of strong near-field ground motions characterized by prominent pulses and high-amplitude spikes in the acceleration and velocity time histories of selected three-component earthquake records. the distinct appearance of high-amplitude spikes and long-period velocity pulses due to forward directionality effects in the site and the fault rupture process indicates the characteristics of strong near-field records. dynamic behavior of structures under such earthquake records has many complexities. however, due to the stochastic nature and physical properties of strong near-field records containing forward directivity effects, there are evident needs to develop comprehensive computational approaches to determine the extended viewpoints in seismic performance assessment of structures.in this context, the seismic response parameters of the considered structures were assessed through nonlinear time history analyses (ntha) and incremental dynamic analyses (ida). the lateral displacement profiles, lateral drift concentration patterns, and peak interstory drift ratios were comparatively evaluated across the different structural configurations. furthermore, fragility curves were developed based on a log-normal probabilistic distribution, and the probability of exceeding distinct performance limit states (i.e., immediate occupancy (io), life safety (ls), and collapse prevention (cp)) was quantified. additionally, the seismic resilience strength index (also referred to as the hard resilience parameter) was calculated to assess the structural capacity for functionality retention under extreme seismic loading scenarios.the assessment of numerical outcomes indicates that forward directivity-induced velocity pulses significantly increase interstory drift demands, particularly in the lower and mid-height zones of the 20-story structure. the implementation of semi-rigid connections resulted in increased peak drift values by approximately 18% and 21% in the 10- and 20-story structures, respectively, when compared to their fully rigid counterparts. moreover, the influence of wave propagation phenomena was found to amplify the drift demand in the height range of approximately 0.2h to 0.3h in the 20-story model, highlighting the sensitivity of tall structures to ground motion characteristics.comparative ida results reveal that, at equal drift levels, frames with semi-rigid connections required higher peak ground acceleration (pga) values to reach specific damage states, suggesting a delayed performance degradation at certain thresholds. nevertheless, fragility assessments indicate that at a constant pga value (e.g., 0.4g), the probability of reaching the io state was higher in semi-rigid frames (about 30.49% and 74.89% for the 10- and 20-story configurations, respectively) compared to 22.26% and 66.80% in fully rigid systems. numerically different trends were observed for the ls and cp limit states, though the comparative probabilities varied depending on building height and connection type.the computed seismic resilience strength indices demonstrate that, provided the strong column–weak beam principle is observed and torsional stiffness capability is adequately addressed, the seismic response and resilience indices of both connection configurations exhibit significant convergence. this convergence suggests that both studied systems are capable of maintaining structural stability and preventing collapse under severe ground excitations. particularly, the semi-rigid 20-story configuration exhibited a more favorable resilience trend under increasing seismic intensities.