International Institute of Earthquake Engineering and SeismologyJournal of Seismology and Earthquake Engineering1735-166920120180101Study on Seismic Response of Asymmetric Framed and Bundled Tube Resistant Skeletons in Near-Field Zones240789ENSaeid SohrabifardScience and Research Branch, IAU, TehranAfshin Meshkat-DiniKharazmi UniversityMohammadreza MansooriScience and Research Branch, IAU, TehranAbdolreza Sarvghad-MoghadamInternational Institute of Earthquake Engineering and Seismology (IIEES)Journal Article20160824In this research, the seismic performance capabilities of both framed and bundled tube systems are studied in order to assess the dynamic response of symbolic asymmetric mid-rise steel structures subjected to both far and near-field earthquake records. For this purpose, two 10 story structural models based on framed and bundled tube skeletons were selected and designed. The main criterion considered in selecting strong earthquake records for performing nonlinear time history analyses is the existence of high amplitude and long period coherent pulse or multiple pulse features in the ground velocity time history. The mentioned powerful velocity pulse makes more seismic demands and would cause a complicated 3D dynamic response which conveys the maximum seismic drift demand from lower stories to middle or even upper ones. Yet, the participation of higher vibration modes in seismic behavior of the studied structures were also taken into account. Overall, seismic response parameters of asymmetric rigid framed tube and bundled tube skeletons are not effectively sensitive to small amounts of mass eccentricity. Moreover, this research analytical assessments show larger amplitude for the seismic nonlinearity of plastic hinges in flexible edges of the structure plan compared to stiff edges. Additionally, the floors dynamic torsional movements cause unequal yielding mechanisms, which are formed in the sided bending frames. Moreover, during the aforementioned process, the frames located at one side of the plan would reach to collapse prevention performance level (CP). Finally, it is observed that rigid framed tubes and bundled tubes can satisfy the Iranian design code restrictions for story drift.http://www.jsee.ir/article_240789_58fd9db158ceddc01b7efae7d80c79dd.pdfInternational Institute of Earthquake Engineering and SeismologyJournal of Seismology and Earthquake Engineering1735-166920120180101Experimental Study of an All-Steel Two-Segment Core Buckling Restrained Brace240790ENMohammad Javad GoodarziIIEESFreydoon ArbabiIIEESJournal Article20161121Buckling Restrained Braces (BRBs) have been exceedingly used for resisting seismic forces in framed structures because of their advantages of non-buckling and large energy absorption capacities. A type of fully steel brace has been designed in the present study that provides ease of construction and replacement of the core. The term multi-zone indicates that the part of the core undergoing plastic deformation is divided into two or more segments in order to provide a more uniform distribution of the plastic deformation. In other words, the core consists of two or more segments that can become plastic. The end parts of the core and shield are so designed as to eliminate the problems that have existed in the previous designs. The aim here is to produce a robust type of brace that can be constructed without strict building requirements, and the test results show that this has been achieved. Three ½ scale specimens were constructed for testing. These specimens were tested under quasi-static loading up to a target displacement. The results for all three specimens tested show that minimum values of parameters specified by the AISC Steel code (maximum compressive stress factor, b= 1.3, and minimum energy absorption factor h =200 ) have been achieved and in all cases they exceeded the code requirements by a large margin (here: bmax= 1.21, hmin= 1102 ). In addition, each specimen was capable of carrying several additional cycles of loading (11 or more) at the end of the test. That is, they are more robust against fatigue than that specified by the said AISC code. Cyclic behavior of the specimens showed high energy absorption capabilities with strains of up to 4.6%. Based on the test results, it can be concluded that the multi-zone core BRB's with stiffened shield and restraining device tested here are suitable for use in new buildings as well as in retrofit of existing structures. The idea of using multi-zone cores not only allows for a better distribution of plastic region, but also enables us to stabilize the shield to the core at the middle zone, where no plastic deformation takes place. In this way, the stability of the shield is achieved by a simple mechanism without requiring elaborate details of a stopper.http://www.jsee.ir/article_240790_785155f663e91f49427b26122e890ef2.pdfInternational Institute of Earthquake Engineering and SeismologyJournal of Seismology and Earthquake Engineering1735-166920120180101Effect of Earthquake Frequency Content on 3D Sloshing in Rectangular Tanks240791ENHamidreza MohammadiShahid Beheshti UniversityMohammad SafiShahid Beheshti UniversityJournal Article20170111Earthquake frequency content has a significant effect on sloshing wave amplitude and height in liquid storage tanks. In this paper, the finite element method had been used to obtain the three dimensional fluid-structure interaction responsen of the rectangular tanks to access the sloshing interference effects at the tank corners under various seismic input motions with different frequency contents. The flexibility of the tank wall as well as the structural and fluid damping have been taken into account to obtain more reliable and realistic results. It has also been shown that the 3D sloshing interference may increase the total wave height significantly at the corners of the tanks compared to the values presented in the design codes, which shows the maximum sloshing wave with much lower values and at a different location. It has been finally shown that the 3D sloshing effects relates to the ratio of the width and the length of the tank.http://www.jsee.ir/article_240791_cd2c1a630fff999d33331fb2bdff056a.pdfInternational Institute of Earthquake Engineering and SeismologyJournal of Seismology and Earthquake Engineering1735-166920120180101Heat Induction Technique for Seismic Retrofit of Steel Beam to Column Connections240792ENMohammad BahiraiSemnan University, SemnanMohsen GeramiSemnan University, SemnanJournal Article20180502The concrete slab in existing buildings presents a problem for economic considerations in seismic retrofit projects. Unless the concrete slab is removed, it is impossible to modify the top flange and its welded joint. Meanwhile, as the majority of reported damages occurred in the bottom flange of the beam during the past earthquakes, it is anticipated that modifying only the bottom flange may be sufficient to significantly improve the performance of the steel frame connections. Making a ductile fuse in the beam section through weakening and gaining the most possible plastic behavior from the beam can be a suitable solution. In current research, a new and practical rehabilitation scheme based on heat induction to the bottom flange of the beam was developed and experimentally validated. Accordingly, three large-scale steel moment frame connections containing one reference (Pre-Northridge) and two retrofitted connections were tested under cyclic loads. The experimental results showed near weld fracture in the reference specimen at story drift of 5.5 % with no qualified plastic behavior for special moment frames.In connections retrofitted through heat induction (annealing of the beam material), plastic hinge occurred at 6% story drift in weakened section far enough from the column face. The main advantage of this technique was low stress demands in near-weld region. Meanwhile, as the beam was heated with no material removal, the out of plane buckling resistance was similar to that of the reference specimen. Strength degradation of the retrofitted connections occurred gradually with no brittle failure as opposed to the reference specimen. The retrofit technique can be easily achieved through a handmade torch and a laser thermometer that simplifies its application in situ.International Institute of Earthquake Engineering and SeismologyJournal of Seismology and Earthquake Engineering1735-166920120180101Analytical Evaluation of Seismic Sloshing Reduction by Suspended Annular Baffle (SAB) in Cylindrical Floating Roof Liquid Storage Tanks240793ENMahmood HosseiniIIEESAmirhossein SoroorIIEESJournal Article20180813Sloshing has been known as the main cause of seismic damages to floating roof oil tanks in past earthquakes. In a previous study, conducted by the authors, the employment of a Suspended Annular Baffle (SAB) was introduced as a countermeasure for seismic sloshing reduction, and its efficiency was shown through a series of laboratory tests by shake table on a small cylindrical tank subjected to harmonic excitations with various amplitude and frequencies as well as seismic excitations using input earthquakes. In the present study, an analytical formulation has been developed for obtaining the dynamic response of floating roofs, subjected to sloshing, with and without SAB, based on velocity potential function and Lagrange equations of motion. To show the validity of the analytical solution, the results have been compared with those of the laboratory tests. Comparisons show that the presented analytical formulation is in good agreement with experimental study, so that the prediction of the maximum sloshing heights in cases of harmonic and seismic excitations can be done with more than 95% and 90% precision respectively.International Institute of Earthquake Engineering and SeismologyJournal of Seismology and Earthquake Engineering1735-166920120180101Seismic Behavior of Studded Steel Coupling Beam Linked to RC Shear Wall240794ENMohammad A. NahviniaIIEESAbbas Ali TasnimiTarbiat Modares UniversityJournal Article20180303Steel coupling beams are increasingly used in coupled wall systems in medium to high rise buildings for high seismic prone areas. Recent investigations focused on interactions between steel coupling beams and reinforced concrete wall in connection region. However, due to lack of data, effect of studs practically utilized in connection zone is not fully understood. Therefore, the major variable in the experimental test includes studs on beam flanges. On the other hand, the test complemented on specimen only considered one half of steel coupling beam and an individual wall, which is different from actual conditions of coupled walls. To address the gap in the previous study, the effects of this difference and concentrated transverse reinforcement around the connection zone investigated through finite element modeling. Results showed that the application of studs could decrease the required embedment length in wall face if reinforcement around the embedded beam were properly placed. The findings proved that tests half assembly of coupled walls in comparison with total assembly have considerably underestimate results.