In this work, a new method for nonlinear time-history earthquake analysis of 2D steel frames by a fiber plastic hinge method is presented. The beam-column element based on the displacement-based finite element method is established and formulated in detail using a fiber plastic hinge approach and stability functions. Geometric nonlinearities are taken into accounting by stability functions and the geometric stiffness matrix. A nonlinear dynamic algorithm is established based on the combination of the Newmark integration method and the Newton-Raphson iterative algorithm for solving dynamic equations. The proposed program predicts the nonlinear inelastic responses of 2D steel frames subjected to earthquakes as efficiently and accurately as commercial software. This study also shows that the initial residual stresses of steel should be considered in nonlinear inelastic time-history earthquake analysis of 2D steel frames while SAP2000 does not consider the effects of residual stresses.

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Nonlinear Inelastic Earthquake Analysis of 2D Steel Frames

In this study, a new method for nonlinear analysis of 2D steel frames, by improving the conventional plastic hinge method, is presented. The beam-column element is established and formulated in detail using a fiber plastic hinge approach. Residual stresses of I-shape sections are declared at the two ends through fibers. Gradual yielding by residual stresses along the member length due to axial force is accounted for by the tangent elastic modulus concept. The P-δ effect is captured by stability functions, whereas the P-Δ effect is estimated by the geometric stiffness matrix. A nonlinear algorithm is established for solving nonlinear problems. The present study predicts the strength and behavior of 2D steel frames as efficiently and accurately as the plastic zone method did.

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Nonlinear Inelastic Analysis of 2D Steel Frames : An Improvement of the Plastic Hinge Method

The strong column-weak beam principle, one of the earthquake resistant building design theories, require the connection area to be strong enough so that the plastic hinge forms in the beam. One of the proposed solutions is to strengthen the column-beam connection zone in steel connection with haunches. This study aims to look at parametrically behavior of column-beam haunched connections under the 100mm vertical displacement controlled loading using the finite element method. To obtain this, a total number of 21 finite elements model with 15, 30, and 45 degrees angles and 6 various stiffener types has been modeled by ABAQUS software. The research later discussed behavior of underlying components of haunch connections models such as the load-displacement curve, bearing capacity, extended end plate bending, stress distribution, and the position of the plastic hinge's development after finite element analysis. The study found that decrease in haunch angle improve the connection's bearing capacity, while in this case, the failure modes and plastic hinges will occur close to the joints which does not meet the code requirements. The article concludes that the 30-degree haunch angle is the most appropriate one in haunch connection and the three parallel and K-stiffeners is the most suitable reinforcement type for the haunched connections. 

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Effect of The Haunch Angle and Stiffener Types on Column-Beam Connection Behaviour Under Static Loading

Beam-to-column connection is a rigid connection used in steel moment frames which acts as the main resisting system in structural design. Haunches with double beam section height at the eave, ridge and crane bracket are usually used to resist the large bending moment at the critical locations of the steel frames. Damper devices can be used as the main source of producing forces used to reduce the bending moment due to different static and dynamic loads. This study focuses on improving the steel beam-column connection with the proposed control system in the eave connection which can also be used under the bracket which supports crane beam in industrial buildings. The purpose of this study is to describe the development of the beam-column steel connection incorporating dampers installed to beam bottom flange to reduce the effect of applied load on the frame without the need to create haunches to make the connection design more efficient.

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N. W. Bishay-Girges

Papers

Improved Steel Beam-Column Connections in Industrial Structures