توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Behavior of Top–Seat Angle Connections Under Combined Tension–Moment Loading
نویسنده(ها):
اطلاعات انتشار: سومین کنفرانس ملی بهسازی و مقاوم سازی ایران، سال
تعداد صفحات: ۸
Bolted top and seat angle connections are mainly designed to sustain gravitational loads of simply supported steel beams. However, the inherent flexural resistance of such connections may not be ignored when an accurate analysis of semi–rigid steel frames is desired. Current research aims at studying moment–rotation behavior of this type under combined moment and axial tension force. Several refined 3D finite element (FE) models were created based on the previous experimental studies and their accuracy is examined comparing by results of previous experimental studies. This study showed that axial tension force reduces connection rotational stiffness and moment capacity. Based on the results obtained from analyzing a series of finite element models under combined axial tension and moment loading an equation is presented to estimate affected moment–rotation response of such connections in terms of the connection geometrical properties, its moment–rotation response in the case of zero axial force and an expected axial tension force.<\div>

۲Upgrading of bolted top–seat angle connections performance Adding double web angles
نویسنده(ها):
اطلاعات انتشار: سومین کنفرانس ملی بهسازی و مقاوم سازی ایران، سال
تعداد صفحات: ۹
In this paper, a parametric study was conducted to investigate the moment–rotation behavior of top and seat angle connections using nonlinear finite element (FE) method. Based on the experiments carried out by preceding researchers, several refined FE models were created in which the geometrical and mechanical properties of connections were as parameters. Eight node solid elements were used to model all of the connection components such as beam, column, angles and bolts. The effect of interactions, such as slippage of bolts and frictional forces, were modeled using surface contact algorithm. To evaluate the connection behavior more precisely, pre–tensioning forces were also applied on bolt shanks as the first load case. Comparing the results of numerical modeling and test results, good agreement was observed, especially in linear range of moment–rotation curves. To study the efficiency of the adding double web angles to enhance the rotational stiffness and moment capacity of bolted top–seat angle connections, models were created with different size and properties and the effect of each parameter on connection behavior was studied. Then the study was extended by evaluating the role of the web angles on seismic performance of a selected semi–rigid frame. The frame was modeled using bar elements and relative stiffness of connections was considered and modeled using zero length joint elements. The result of nonlinear time–history analysis showed that adding web angles to frame connections will reduce the story drift and increase the energy absorbance capacity of the structure.<\div>

۳Moment–rotation behavior of bolted Top–seat angle connections
نویسنده(ها): ،
اطلاعات انتشار: هشتمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۸
Bolted top and seat angle connections are mainly designed to sustain gravitational loads of simply supported steel beams. However, the inherent flexural resistance of top–seat angle connections may not be ignored when an accurate analysis of semi–rigid steel frames is desired. The goal of the current study is to find a new moment–rotation relation to estimate the behavior of connections of this type. Semi–analytical equations are proposed for this purpose based on the data bank, which is created using finite element simulation. Several refined 3D finite element models were created based on the previous experimental studies and their accuracy is examined through a comparison to test results from previous studies and other published numerical models. The presented new semi–analytical method covers some deficiencies of the previously proposed methods, and the accuracy of this approach is evaluated comparing its results with those of the other methods. The applicability of the presented method is evaluated, and it is shown that the model estimates the moment–rotation response of this type of connections.<\div>

۴Nonlinear Dynamic Analysis of Semi–Rigid Frames with Bolted Angle Connections
اطلاعات انتشار: هشتمین کنگره بین المللی مهندسی عمران، سال
تعداد صفحات: ۸
In this paper, a parametric study was conducted to investigate the moment–rotation behavior of top and seat angle connections using nonlinear finite element (FE) method. Based on the experiments carried out by preceding researchers, several refined FE models were cre ated in which the geometrical and mechanical properties of connections were as parameters. Eight node solid elements were used to model all of the connection components such as beam, column, angles and bolts. The effect of interactions, such as slippage of bolts and frictional forces, were modeled using surface contact algorithm. To evaluate the connection behavior more precisely, pre–tensioning forces were also applied on bolt shanks as the first load case. Comparing the results of numerical modeling and test results, good agreement was observed, especially in linear range of moment–rotation curves. To study the efficiency of the adding double web angles to enhance the rotational stiffness and moment apacity of bolted top–seat angle connections, models were created with different size and properties and the effect of each parameter on connection behavior was studied. Then the study was extended by evaluating the role of the web angles on seismic performance of a selected semi–rigid frame. The frame was modeled using bar elements and relative stiffness of connections was considered and modeled using zero length joint elements. The result of nonlinear time–history analysis showed that adding web angles to frame connections will reduce the story drift and increase the energy absorbance capacity of the structure.<\div>

۵Seismic performance of semi–rigid frames with connection dampers
اطلاعات انتشار: هشتمین کنگره ملی مهندسی عمران، سال
تعداد صفحات: ۸
To reduce dynamic response of a semi–rigid frame with bolted connections, energy dissipation materials may be placed at a connection between the end plate and column flange or between the angle and member flange. In this article a three–span three bay frame with semi–rigid connections having threedifferent capacities and energy dissipation materials analytically modeled by idealizing semi–rigid connection and energy dissipation materials as rotational spring and damper, respectively. The numerical model included nonlinear connection behavior, member yielding and geometrical nonlinearity of thestructure. The pushover and dynamic analyses of the frames were performed using OPENSEES analysis program and dynamic analyses of frames with and without connection dampers show that there is an optimal damper damping coefficient by which the seismic responses of semi–rigid frame, including lateral displacements can be significantly reduced<\div>

۶Load Carrying Capacity of CompositeCastellated Beams
نویسنده(ها): ،
اطلاعات انتشار: پانزدهمین کنفرانس دانشجویان عمران سراسر کشور، سال
تعداد صفحات: ۸
Due to unique geometry of castellated steel beams and existence of the web holes, estimation of shear load carrying capacity of these beams is rather different from traditional beams with solid webs. Shear capacity estimation of castellated beams becomes even more complicated when these beams are used in compositefloor systems due to contribution of the concrete slab. Herein, a numerical study is performed to assess the shear capacity of composite castellated beams by using nonlinear finite element (FE) method. A benchmark parametric FE model is created and validated comparing the test results. This comparison showed a goodaccuracy for the model. This model is used in the parametric study of shear response of composite castellated beams. Different FE models of these beams are analyzed and the obtained results show that the floor slab can have a considerable contribution in shear capacity of composite castellated beams<\div>

۷Load carrying capacity of composite castellated beams
نویسنده(ها): ، ،
اطلاعات انتشار: پنجمین کنفرانس ملی و اولین کنفرانس بین المللی سازه و فولاد، سال
تعداد صفحات: ۱۰
Due to unique geometry of castellated steel beams and existence of the web holes, estimation of shearload carrying capacity of these beams is rather different from traditional beams with solid webs. Shearcapacity estimation of castellated beams becomes even more complicated when they are used incomposite floor systems, due to the contribution of the concrete slab. Herein, a numerical study isperformed to assess the shear capacity of composite castellated beams by using nonlinear finite element(FE) method. A benchmark parametric FE model is created and validated comparing the test results. Thiscomparison showed a good accuracy for the model. This model is used in the parametric study of shearresponse of composite castellated beams. Different FE models of these beams are analyzed and theobtained results show that the floor slab can have a considerable contribution in shear capacity ofcomposite castellated beams.<\div>
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