Pal. Jour. V.16, I.3, 2017, Copyright 2017 by Palma Journal, All Rights Reserved Available online at:

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1 Pal. Jour. V.6, I., 7, 85-9 Copyright 7 by Palma Journal, All Rights Reserved Available online at: The Investigation and Comparison of Roof Drift in Bending Steel Frames with Discontinuous Steel Shear Walls at a Height Using Nonlinear Static and Dynamic Analysis Saeed Matooreipour Mohammarei, Corresponding Author, M.A. Student of Structural Engineering, Higher Education Institute of Khuzestan Jihad University saeedmpm@yahoo.com Mehdi Mahdavi Adeli Assistant Professor at the Department of Civil Engineering, Shushtar Branch, Islamic Azad University Abstract In recent years, steel shear walls have been used in buildings as a strong structural material. In general, steel shear walls comprise of a steel plate, two peripheral columns and horizontal beams. The main function of steel shear walls is resistance to the sheer force of floors and the reversal anchors caused by lateral loads. Generally, the opening of the frame is laterally braced in all the floors for seismic resistance. However, due to the architectural limitations caused by this operation, discontinuous bracing is sometimes done by using steel shear walls alternatively in different openings in the floors. Therefore, it is necessary to have a better understanding of the effects of the bracing system discontinuities on the seismic behavior. In this research, the discontinuity effect of the bracing system on the maximum relative displacement of the roof was investigated using SAP software and nonlinear static and dynamic analyses in order to examine the seismic behavior of the discontinuous bracing system. The results demonstrated that in four-storey and eight-storey models, the drift of the regular models is less than that of the irregular models in the target displacement. Keywords: Steel shear walls without stiffeners, discontinuous bracing, roof drift, nonlinear dynamic analysis, nonlinear static analysis Introduction Over the past three decades, the steel shear walls have been used in designing and strengthening the buildings as resistant systems with an optimal seismic performance against lateral loads. A steel shear wall contains a number of steel plates surrounded by beams and columns. To put it in simple words, the wall is similar to a steel cantilever and plate girder whose plates, columns and beams appear as its body, wings and stabilizers []. This system has many applications in tall buildings or buildings with a medium height. The capacity of this system also increases by an increase in the thickness of the plate or the use of stiffeners on the first plate while the first case is rather uneconomical []. The aim of this research study is to calculate the roof drift in the bending steel frame with discontinuous steel shear walls installed from a height through nonlinear dynamic and static analyses. To do this, models with, 8 and levels, four 5m openings, and the fixed height of m were considered and three types of irregularities with three earthquakes that were close to faults were examined through a nonlinear dynamic analysis and a triangular load pattern under nonlinear static analysis. Research Background Research on steel shear walls began in 9 and extensive research on this system started in the 97s. Yamada (99) reported periodic tests on steel shear walls and composites. The samples that were subjected to continuous and fixed load were placed in a position corresponding to their diameters. The rupture also appeared as the fracture of the surface in rigid frames border. The samples showed a very ductile behavior and the tension field formed at the length of the diameter []. Elgaaly and Caccese (99) performed some Palma Journal

2 86 S.M.Mohammarei and M.M.Adeli research on three samples of steel shear walls on a scale of one quarter. They found out that the changes of the angle (α) ranging between 8 and 5 degrees have an insignificant effect on the initial hardness and the 5.% difference of the final resistance []. Yamada et al. (996) reported the results of periodic and fixed tests on steel-plate shear walls. All samples showed compression in hysteresis loops due to the buckling in the pressure field []. Torii et al. (996) also studied the application of steel walls with low resistance in tall buildings [5]. Astaneh-Asl () conducted a comprehensive study in elaborating the details of the analysis and design of steel shear walls. Stiffened and unstiffened panels were both examined by the researcher. He suggested that solid plates should be used without stiffeners unless the installation of an opener needs to be used somewhere [6]. Topkaya and Kurban (9) investigated the natural sequence time of the steel shear wall system. In that research, it was observed that the buckling effect of solid sheets could be ignored during the design. On average, an increase of 7 percent was observed in this study at the time of the sequence in this system due to the effect of buckling [7]. Gholipour and Alinia (6) worked on the multi-level structural behavior with different opening widths. They researched the design requirements of the AISC- regulations concerning the limits of the opening width [8]. The characteristics of models, the modeling method and validation In this study, the design of the steel shear wall and the lateral elements of the steel shearing wall (i.e. beams and columns) were taken into account based on the American AISC regulations. The modeling of the steel shear wall was done using the SAP software by tensile and unidirectional bands with two-end joints in the nonlinear static analysis and bidirectional bands in nonlinear dynamic analysis. Frames that are previously braced with unstiffened steel shear walls with, 8, levels, four 5 m openings, m heights, and m load widths were considered. Once more, three models of steel shear walls were considered for the structure with different orders which were braced from a height with the plate discontinuity of the steel frame. In order to understand the impact of the discontinuity of the steel shear wall system at the height, the regular and attached models were first examined. Then, multiple models were examined by changing the position of the shear wall in the openings. In this research, an attempt has been made to investigate the irregular models that are installed at a height and are used somewhat rationally. Therefore, the number of discontinuous and irregular models has been limited. In what follows, the investigated models have four illustrated levels. Figure also shows the irregularity of models with 8 to storeys. In the examined models, what is meant by A, B, C is the models with four, eight and twelve storeys respectively. The steel shear walls have been modeled by the tensile two-end joint bands with an angle of degrees. The thickness of steel shear walls for, 8 and floors is, and 5 millimeters respectively and the type of the steel in the bending frames and the steel shear walls is ST7. A A-

3 Roof Drift in Bending Steel Frames with Discontinuous Steel Shear Walls 87 A- A- Figure. The regular and irregular four-storey models The tensile loading of the models was done based on the sixth article of the national construction regulations of Iran. The dead load of the floors was 5 kilograms per square meter and the live load was kilograms per square meter [9]. The earthquake loading was calculated based on the regulations of the building design for earthquakes with the th edition standard-8. The building was constructed in a place with the soil of the third type and with a considerable earthquake risk []. For validation, Driver s laboratory sample work was examined. In Figure, the feature of profile sections that were used and the thickness of steel shear walls can be observed []. Figure. The model developed by Driver et al. Table. The characteristics of the modules and materials used in the model by Driver et al. Modules and category wall category wall category wall W 8 W 6 W5 8 Elastic module (E) (MPa) Yield tension (Fy) (MPa) Final tension (Fu) (MPa)

4 88 S.M.Mohammarei and M.M.Adeli Experimental Analysis base shear(ton) displacement(cm) Figure. The diagram of the basic shear displacement of the first level in Driver s laboratory sample As observed, the results of the pushover analysis and the experimental results are very consistent. The analysis of results In this section, the results derived from the discontinuity of the steel shear wall installed at a height and its effect on the roof drift of the structure will be discussed. The roof drift is first examined in nonlinear static analysis and then in nonlinear dynamic analysis. Roof drift (Nonlinear static analysis) According to the Fourth Edition 8 standard, the maximum lateral displacement of a structure in nonlinear analysis must not be more than. times larger than the below relations. () Up to five-storey buildings.5h () Other buildings.h In the above relations, h indicates the height from the level. In this section, the roof drifts of different models are discussed. a a Model Roof Drift cm The percentage of difference compared to the regular model Model Roof drift cm The percentage of difference compared to the regular model Model Roof drift cm The percentage of difference compared to the regular model Table. A comparison of the roof drifts of four-storey models A.87 - A % A % Table. A comparison of the roof drifts of eight-storey models B. - B-.6 +7% B-. +8% Table. A comparison of the roof drifts of twelve-storey models C.58 - C-.7% -6% C-.78-6% A % B-.6 +6% C-. -5% Roof drift (nonlinear dynamic analysis) In this section, to compare the results of the static and dynamic analyses, the maximum relative displacement of the roof under three earthquakes close to Dihok, Tabas and Manjil faults was calculated

5 Roof Drift in Bending Steel Frames with Discontinuous Steel Shear Walls 89 using nonlinear dynamic analysis and coefficients of different velocities (. g ranges) for a displacement in the nonlinear static analysis. A A- A- A Figure. The maximum relative displacement of the roof of the four-storey model under Dihok record A A- A- A Figure 5. The maximum relative displacement of the roof of the four-storey model under Tabas record A A- A- A acceleration (g) Figure 6. The maximum relative displacement of the roof of the four-storey model under Manjil record

6 9 S.M.Mohammarei and M.M.Adeli As observed in, 5 and 6 models, the level of roof drift of all four-storey models is close to each other up to.8 g velocity and the drifts in the regular models are less compared to the irregular models. B B- B- B Figure 7. The maximum relative displacement of the roof of the eight-storey model under Dihok record B B- B- B Figure 8. The maximum relative displacement of the roof of the eight-storey model under Tabas record. B B- B- B Figure 9. The maximum relative displacement of the roof of the eight-storey model under Manjil record

7 Roof Drift in Bending Steel Frames with Discontinuous Steel Shear Walls 9 C C- C- C- roof drift(cm) Figure. The maximum relative displacement of the roof of the twelve-storey model under Dihok record. C C- C- C-. roof drift(cm) Figure. The maximum relative displacement of the roof of the twelve-storey model under Tabas record C C- C- C Figure The maximum relative displacement of the roof of the twelve-storey model under Manjil record

8 9 S.M.Mohammarei and M.M.Adeli It is clear in the diagrams of the eight-storey model that the roof drift does not follow a constant pattern and, at different velocities, the drift of the regular model is either lower or higher than that of the regular model at different times. The drifts of the regular models are higher than that of the irregular models in all three records of -storey models []. Results The relative displacement of the roof in the pushover analysis of the irregular four-storey models increased significantly and the same increase was observed in the irregular eight-storey models but the rate of this increase was much lower than the four-storey models. In the irregular twelve-storey models, the relative displacement dropped and in almost all irregular models the decrease rate is similar. In the nonlinear dynamic analysis, the level of drift in the irregular four-storey models is similar and is higher than the regular model. The level of drift in eight-storey models does not have a fixed rate. As for twelve-storey models, the drift of the regular model is higher than the irregular model and the drifts of the irregular models are similar. The examination of the model drifts in displacing the target in pushover and nonlinear dynamic analyses showed that, in four and eight storey models, the drift of the regular models was lower than the irregular ones and the results of the pushover and nonlinear dynamic analyses are different in the twelve-storey model. The seismic behavior of discontinuous models of and arrangements were very close and were not significantly different from arrangement in most cases. The shear behavior was recorded for the dual system of the bending frame and the steel shear walls in this research. The cases of damage in the models first appeared in the steel shear walls, the beams and columns and these cases are in accordance with the objectives of the system design. References [] Gholhaki, Majid, Sabouri, Saeed (9). The effect of the tensile coefficient on the coefficient of the steel shear wall behavior with thin plates. Scientific and Research Journal of Structure and Steel. [] M.M. Alinia., R. Sarraf Shirazi., 9. "On the design of stiffeners in steel plate shear walls". Journal of Constructional Steel Research, pp 69_77. [] Astaneh-Asl.,. "Seismic Behavior and Design of Steel Shear Walls". Department of Civil and Environmental Engineering University of California, Berkeley. [] Elgaaly, M. and Caccese, V., 99. "Post-buckling Behavior of Steel- Plate Shear Walls under Cyclic Loads". J. of Str. Engrg. ASCE, 9, n., pp [5] Troy, R.G., and Richard, R. M., 988. " Steel Pate Sear Wall Design".Struct. Engrg. Review, (). [6] Design guide., 5. Steel plate shear wall. American Institute of Steel Construction, Chicago, IL. [7] Topkaya, C. and Kurban, C. O., 9. "Natural period of steel plate shear wall system". Journal of Constructional steel research, Vol. 65, No., PP [8] M.M. Alinia, Gholipour., 5."Behavior of multi-story code-designed steel plate shear wall structures regarding bay width". Journal of Constructional Steel Research, 56. [9] Office of the National Building Regulations (9). The sixth section of the National Building Regulations, Department of Housing and Urban Development. [] Research Center of Way, Housing and Urban Development (9). Regulations of building design for earthquake, standard 8, Department of Housing and Urban Development. [] Shishkin. J.J., Driver. R.G., And Grondin., 5. " Analysis Steel Plate Shear Wall Using Conventional Engineering Software". proceedings of the rd Annual General conference of the Canadian society for civil Engineering, Toronto. [] Matooreipour Mohammarei Saeed (95). "An assessment of discontinuous nonlinear behavior of steel frames with steel shear walls in height". Master's Thesis, Institute of University Jihad, Khuzestan.