Assement of the Seismic Behavior of Eccentrically Braced frame with Vertical and Horizontal Link Made of Easy-Going Steel and Constructional Steel

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1 Research Journal of Applied Sciences, Engineering and Technology (): 9-9, ISSN: - axwell Scintific Organization, Submitted: January, Accepted: arch, ublished: June, Assement of the Seismic Behavior of Eccentrically Braced frame with ertical and Horizontal Link ade of Easy-Going Steel and onstructional Steel Yaser ozaffary Jouybary and Abbas Akbarpour Nikghalb Jouybar Branch, Islamic Azad University, Jouybar, Iran Deptartement of ivil Engineering, Islamic Azad University Tehran South Branch, Iran Abstract: Eccentrically braced frames (EBFs) are a lateral load resisting system for steel building that are capable of combining high stiffness in the elastic rang with good ductility and energy dissipation capacity in the inelastic rang. There are two type eccentrically braced frame; eccentrically braced frame with vertical link and horizontal link.eccentrically braced frame with vertical link prevent rotation mean beam and cause decreased damage in the main structure. During extreme loading it is anticipate that the link beam will deform inelastic ally with significant ductility and energy dissipation. In the study, lower strength steel is used for the link beam according to the general concept of Easy-Going steel (EGS).the link beam made of EGS yields in improved. The obtain this objectives, -D steel building in, and story by short link beams made of Easy- Going steel and constructional steel were modeled. near-field ground motions were utilized as input ground motions. Based on nonlinear analysis, the values of story displacement, inter story drift, story acceleration and velocity, base shear, for shear link beams system under near - field earthquake were investigated and the results have been discussed. It is found that the use of EGS in link beam decrease lateral displacement.by decrease the lateral displacement, damage in the structure decreased. Also the link beam made of EGS yields less displacement and so the energy dissipation capacity increased. It is found that the use vertical link in the eccentrically braced frame prevent rotation mean beam; also system EBFs with vertical link yielded lees displacement and so the energy dissipation capacity increased. Key words: Eccentrically Braced Frame, ertical Link, Horizontal Link, Easy-Going Steel INTRODUTION Because of proper seismic characteristic of eccentrically braced frames, the use of lateral resisting structural system is quite popular in the region with high level of seismicity. In the type of frames a distance is created between the two ends of the bracing members, bracing member and column or bracing member and beam, is called link beam(e), as shown in Fig.. The link beam acts as a fuse and prevents the other members of frame to enter the inelastic range. The link absorbs a significant amount of energy by inelastic deformation. One of the advantage of vertical links over their horizontal link counterparts is the exclusion of plastic deformation from the main structure result on no damage in the structural under sever earthquakes; easy and sample rehabilitation; and the replacement of link after earthquake. In this study, Easy-Going steel is used to make the link beam and the behavior of link studied and compared to those of a link made of constructional steel, because the link beam of EGS yields in less displacement and so the energy dissipation capacity is significantly improved (Sabouri and Ziaei, ; ohsenali-rezaeian and Taherkhani, ). ETHODOLOGY echanism of horizontal link beam: The length of link beams effect the behavior of EBFs in linear and non-linear region. In high force the plastic hinges were created in link beam that the kind of these indicates the mechanism of link beams. By writhing the stability equation we have these two boundaries. In this Eq. () is the length of link beam: Shear link beam e. () oment link beam e >. when the length of link beam is between theses limitations both shear and moment mechanisms occur. UB code limits the ultimate rotation of link beams,.9 for shear ones and. for moment ones. AIS limitations are. for shear link and. for moment links. These limitations in Iran code are. for shear link and. for moment links (Tehrani and Haj,). orresponding Author: Yaser ozaffary Jouybary, Jouybar Branch, Islamic Azad University, Jouybar, Iran 9

2 Res. J. Appl. Sci. Eng. Technol., (): 9-9, Fig. : Link in eccentrically braced frame Table : Specification of EGS steel and constructional steel Elasticity Yield stress Ultimate stress modulus (pa) (pa) onstructional steel.e Easy-going steel.e Fig. : The diagram of the moment in frame with single vertical link Fig. : lan building echanism of vertical link beam: For vertical shear links whose moment diagram is illustrated in Fig., in order to achieve the shear hinges formation condition before flexural hinge, due to the unequal moment at the end of link Eq. () considered:. ( K + ) e K =, ( ) () odeling: In the research the EBF systems with vertical and horizontal link with shear behavior made of EGS and ST have modeled. (Table )Short link beam considered equal to. m, in, and numbers of stories, respectively. The height of each story in m.the plan of structure in all stories is similar. This plan has longitudinal spans and spans in other side. Each span has m length, as shown in Fig.. onsideration of soil is according to soil type II (Iran code) similar to zone (UB 9). All models have residential use. The earthquake probabilistic hazard considered very high. For each model loading complete design is separately done according to Iran Earthquake code () (much similar to UB9) and steel design code (much similar to AIS9). IE and plate girders are use for beams, BOX sections are used for columns for doing all step of analysis and design we use program sap v... In research, non-linear static analyses and non-linear dynamic analyses performed. Near-field earthquake: Near-Field earthquake have some characteristic that differ them from Far-Field ones. These earthquakes have higher acceleration and restricted frequency content in higher frequencies that Far-Field ones.(table )Also their records have pulses in beginning of record with high period and high domain. These pulses are much considerable when the forward directivity takes place, therefore the records change from board-band condition to pulse-like ones. All of them have distance less than km (Tehrani and Haj, ). Non-linear static analysis: lastic hinges definition, assignments and non-linear static analysis are done according to Feta. The plastic hinges were produced only in link beam, production of hinges has 9

3 Res. J. Appl. Sci. Eng. Technol., (): 9-9, Table : Specification of near-field motions Number Earthquake Year GA (g) G (cm/sec) GD (cm) Station Bam..9. Bam Tabas 9... Dayhook hi chi TU Kobe o kjma acoima Joshua Golbaf Golbaf Silakhor..9.9 Silakhor 9 Zangiran Zangiran Kocaeli Sakavya Fig. : Base shear-displacement diagrams (pushover curves) regular processes, it mean that before producing plastic hinges in all of stories, the structural do not go under instability and collapse mode. Non-linear static analysis do, are investigate the First plastic hinges in the building with link beam mode of EGS were produced in the less displacement, as the energy dissipation capacity increased. Also are investigate the First plastic hinges in the building with vertical link beam were produced in the less displacement, as the energy dissipation capacity increased. The base shear gets form vertical link, is so lees that base shear get form horizontal link shown in the Fig.. Also the base shear gets form link beamed made of EGS, is so lees that base shear get form link beam made of st shown in the Fig.. For each model, among non-linear static analysis that have we choose critical analysis,as pushover curves shown in the Fig.. -stories -stories -stories H-EBF (St) H-EBF (EGS) -EBF (St) Fig. : omparison base shear buildings -EBF (EGS) Non-linear dynamic analysis: All the non-linear dynamic analyses are as Direct Integration time history. 9

4 Res. J. Appl. Sci. Eng. Technol., (): 9-9, Height (m) Height (m) H-EBF (St) H-EBF (EGS) -EBF (St) -EBF (EGS) Lateral displacement (cm) H-EBF (St) H-EBF (EGS) -EBF (St) -EBF (EGS) Lateral displacement (cm) Fig. : Formation first plastic hinges in the building Tabas, and Earthquske are selected for non-linera dynamic analysis;also effective vertical component Tabas earthquake considred. For each modle, non-linear dynamic analyses done. In a building, all non-linear deformation occurred in link beams which indicate that all the energy dissipation capacity is due to the existence of links and all other parts of the structure remain in the linear range the use of EGS in link beam EBF decreases lateral displacement in different stories in building. In the stories, lateral displacement decrease % in comparison link beam made of st, as shown Fig.. By decreasing the lateral displacement, the moment in the vertical load-carrying member like columns are decreased, as shown Fig., so decreased damaging in the structure and the section structural column decreased. The use of EGS in link beam yields in the less displacement and so the energy dissipation capacity increased. dynamic analyses the amount of relative acceleration and velocity in link beam mode of EGS are less than link beam made of st. Also, Under Near-Field earthquake and under non-linear dynamic analyses the oment (ton.m) Fig. : Roof displacement curves oment (ton.m) Fig. : oment curves for column one story amount of relative acceleration and velocity in vertical link beam are less than horizontal link, as shown Fig. 9. RESULTS The non-linear lateral displacement in EBFs with link beam made of EGS become less than EBF with link beam of st. 9

5 Res. J. Appl. Sci. Eng. Technol., (): 9-9, 9 Relative acceleration (cm/sec) 9 Relative acceleration (cm/s) Relative velocity (cm/s) 9 Relative velocity (cm/s) Fig. 9: omparison relative acceleration and velocity different earthquake The non-linear lateral displacement in EBFs with vertical link beam become more than EBF with horizontal link beam The use of EGS in the link beam decrease lateral displacement. By decrease the lateral displacement, damage in the structure decreased. Also the link beam made of EGS yields less The base shear get from vertical link beam, is so less that base shear get from horizontal link beam. displacement and so the energy dissipation capacity increased. Also the use of EGS in the link beam decreased base shear in comparison link beam made of st. dynamic analyses the amount of relative acceleration and velocity in link beam mode of EGS are less than link beam made of st. Also, dynamic analyses the amount of relative acceleration and velocity in vertical link beam are less than horizontal link. In EBF systems with short links have good performance in the earthquakes. REFERENES ohsenali-rezaeian, S. and S. Taherkhani,. Assessment of the seismic behavior of eccentrically braced frame with double vertical link (D-EBF). The world onference on Earthquake Engineering October -, Beijing, hina. Sabouri, S. and. Ziaei,. A Study on the Behavior of shear Link Beam of Easy-Going steel in Eccentrically Braced Frames. The world onference on Earthquake Engineering October -, Beiging, hina. Tehrani, Z.. and N.L. Haj,. Assessing Seismic Behavior of Eccentrically Braced Frames (EBFs) Due to Near-Field Ground otions. World onferences on Earthquake Engineering October -, Beijing, hina. 9