پديد آورندگان :
عالي زهي، الياس دانشگاه تهران - دانشكده مهندسي عمران، تهران، ايران , قاسميه، مهدي دانشگاه تهران - دانشكده مهندسي عمران، تهران، ايران , ميرقادري، رسول دانشگاه تهران - دانشكده مهندسي عمران، تهران، ايران
چكيده فارسي :
با توجه به كاربرد زياد ساختمان هاي فولادي در ايران و اهميت اتصال هاي خمشي تير به ستون فولادي كه از جمله اجزاء حياتي در اين گونه از ساختمان ها هستند، شناخت بهتر رفتار اتصال هاي ياد شده در برابر زمين لرزه، ضروري است. خصوصيات شتابنگاشت حوزه نزديك متمايز از زلزله حوزه دور ميباشد. برخي از زمين لرزه هاي فاجعه بار رخ داده در ايران از جمله زلزله بم (2003) و زلزله طبس (1978) داراي ويژگي هاي شتاب نگاشت حوزه نزديك بودند، كه اهميت ركورد حوزه نزديك را نشان مي دهد. بنابراين در اين مقاله سعي شده است كه ضابط هاي براي آزمودن اتصال هاي خمشي تير به ستون فولادي موجود در ساختمان هاي فولادي اي كه تحت شتاب نگاشت حوزه نزديك ممكن است قرار بگيرند، ارائه شود. بدين وسيله امكان بررسي رفتار اتصال هاي ياد شده در آزمايشگاه با توجه به دستورالعمل پيشنهاد شده، ايجاد مي شود. همچنين امكان ساخت ساختمان هاي فولادي ايمن تر، فراهم مي گردد. هدف اين مقاله، پيشنهاد پروتكل بارگذاري براي قاب هاي خمشي ويژه فولادي تحت ركوردهاي حوزه نزديك براي ايران مي باشد. براي اين منظور با بررسي زلزله هاي رخ داده در ايران در طول سال هاي متعدد، به تعيين شتاب نگاشتهاي حوزه نزديك پرداخته شد. ساختمان هاي فولادي 3، 5، 7، 9، 12 و 20 طبقه طبق ضوابط و مقررات ايران طراحي و تحليل شدند. سپس براي هر يك از ساختمان هاي فولادي طراحي شده به تعيين قاب بحراني پرداخته شد. براي هر يك از قاب هاي بحراني، ضريب مقياس مشخص شد. پس از انجام تحليل تاريخچه زماني و اعمال شتاب نگاشت هاي پيشنهادي حوزه نزديك به هر يك از قاب هاي بحراني، جابه جايي نسبي طبقه (يا همان زاويه جابه جايي داخلي طبقه) براي تمامي قابها بدست آمده و با هم مقايسه شدند. در نهايت پروتكل بارگذاري براي اتصال خمشي تير به ستون ساختمان هاي فولادي در ايران براي ركوردهاي حوزه نزديك بدست آمد.
چكيده لاتين :
Due to the relatively high use of steel buildings in Iran and the importance of rigid steel beam-to-column
connections, which are among the vital components in this type of buildings, the need to better understand
the behavior of these connections against earthquakes has been noted. Also due to the special characteristics
of the near-field earthquakes, which is different than far-field earthquakes and it has its own characteristics;
and the fact that some catastrophic earthquakes occurred in Iran, such as the Bam earthquake (2003) and the
Tabas earthquake (1978) had the characteristics of the near-field earthquakes, which can show the
importance of the near-field ground motions; the purpose of this study was to propose a loading protocol for
special steel moment- resisting frames under near-field earthquakes for Iran. Therefore, first, by examining
the earthquakes that have occurred in Iran during several years, near-field earthquakes have been selected.
Steel buildings of 3, 5, 7, 9, 12 and 20 floors were designed and analyzed according to the rules and
regulations of Iran, then for each of the designed steel buildings a critical frame was determined; the values
of the scale factors are also specified. After performing nonlinear time-history analysis and applying the
proposed near-field ground motions to all of the critical frames, inter-story drift angles for all frames was
obtained and compared. The third floor of the 3-story critical frame was selected as the critical floor; which
is a story whose results will be used to construct a loading protocol; The basic rainflow counting and
simplified rainflow counting were performed for the critical inter-story drift angles results; The proposed
loading protocol are derived based on the MCE-level seismic hazard and 84th percentile values of key
seismic demand parameters. These parameters are number of damaging cycles, maximum inter-story drift,
sum of inter-story drift range, inter-story drift range and residual inter-story. The rationality of the proposed
loading protocol was justified by showing the cumulative distribution function. The proposed loading
protocol has 23 damage half-cycles, including 3 pulse half-cycles with inter-story drift ranges of 0.060,
0.100 and 0.078 radians; which are calculated by the basic rainflow counting method. The maximum interstory drift was obtained 0.065 radians. In the final half cycle, the mean value is the same as the residual
inter-story drift of 0.03 radians. Also, the sum of the inter-story drift ranges is equal to 0.684 radians. The
proposed loading protocol was compared with the SAC near-field earthquake protocol, the maximum interstory drifts in the proposed protocol is 0.065 radians and in the SAC protocol is 0.06 radians. Furthermore
the pulse cycles in the proposed protocol have inter-story drift ranges equal to 0.060, 0.100 and 0.078
radians; while the three pulse half-cycles at the beginning of the SAC loading protocol have inter-story drifts
of 0.08, 0.05 and 0.04; respectively. Therefore, the proposed loading protocol has a higher inter-story drift
and stronger pulse cycles than the SAC near-field earthquake protocol; but the total number of cycles
defined in the SAC protocol is greater than the proposed protocol.
