• Earthquakes and Structures
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• v.8 no.1
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• pp.253-273
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• 2015

The current investigation has been conducted to examine the effect of gravity loads on the seismic responses of the doubly asymmetric, three-dimensional structures comprising walls and frames. The proposed model includes the P-${\Delta}$ effects induced by the building weight. Based on the variational approach, a 3D finite element with two nodes and six DOF per node including P-${\Delta}$ effects is formulated. Dynamic and static governing equations are derived for dynamic and buckling analyzes of buildings braced by wall-frame systems. The influences of P-${\Delta}$ effects and height of the building on tip displacements under Hachinohe earthquake record are investigated through many structural examples.

• Steel and Composite Structures
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• v.5 no.2_3
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• pp.103-126
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• 2005

This paper describes the theoretical background and underlying principles behind the American Institute of Steel Construction Load and Resistance Factor Design (AISC LRFD) Specification for the analysis and stability design of steel frames. Various analysis procedures that can take into consideration the effects of member instability, frame instability, member-frame interaction, geometric imperfections, and inelasticity are reviewed. Design approaches by which these factors can be incorporated in the design of steel moment frames are addressed. Current specification guidelines for member and frame design in the U.S. are summarized. Examples are given to illustrate the validity of the design equations. Some future directions for the analysis and stability design of steel frames are discussed.

• Journal of Astronomy and Space Sciences
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• v.31 no.1
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• pp.91-99
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• 2014

The atmospheric flow in the 3-Cell model of global atmosphere circulation is described by the Lagrange's equation of the non-inertial frame where pressure force, frictional force and fictitious force are mixed in complex form. The Coriolis force is an important factor which requires calculation of fictitious force effects on atmospheric flow viewed from the rotating Earth. We make new Mathematica platform to solve Lagrange's equation by numerical analysis in order to analyze dynamics of atmospheric general circulation in the non-inertial frame. It can simulate atmospheric circulation process anywhere on the earth. It is expected that this pedagogical platform can be utilized to help students studying the atmospheric flow understand the mechanisms of atmospheric global circulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.729-737
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• 1994

A three-dimensional finite element model of a 20-pin plastic dual-in-line package(PDIP) plugged into a PCE has been developed by using the finite element code ANSYS. The model has been used for thermal characterization of the package during its normal operation under natural convection cooling. Temperature distributions in the package and PCB are obtained from numerical analysis and compared with experimentally measured data. Various cases are assumed and analyzed to study the effects of package and PCB materials on thermal characteristics of PDIP with and without aluminum heatspreader. Thermal dissipation capability of PDIP is greatly increased due to copper die pad/lead frame and heatspreader. However, thermally induced stresses in the package and fatigue life of chip are improved for PDIP with Alloy 42 die pad/lead frame and no heatspreader. It is also found that the role of PCB on thermal characteristics of PDIP is very imporatant.

• Structural Engineering and Mechanics
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• v.65 no.1
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• pp.9-17
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• 2018

This study concerns about calculating exact natural frequencies of frames using a single variable shear deformation theory (SVSDT) which considers the parabolic shear stress distribution across the cross section. Free vibration analyses are performed for multi-bay, multi-storey and multi-bay multi-storey type frame structures. Dynamic stiffness formulations are derived and used to obtain first five natural frequencies of frames. Different beam and column cross sections are considered to reveal their effects on free vibration analysis. The calculated natural frequencies are tabulated with the results obtained using Euler-Bernoulli Beam Theory (EBT) and Timoshenko Beam Theory (TBT). Moreover, the effects of inner and outer columns on natural frequencies are compared for multi-bay frames. Several mode shapes are plotted.

• Steel and Composite Structures
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• v.20 no.6
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• pp.1391-1409
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• 2016

Masonry infill has a significant effect on stiffness contribution, strength and ductility of masonry-infilled frames. These effects may cause damage of weak floor, torsional damage or short-column failure in structures. This article presents experiments of 1/2.5-scale steel reinforced recycled aggregates concrete (SRRC) frames. Three specimens, with different infill rates consisted of recycled concrete hollow bricks (RCB), were subjected to static cyclic loads. Test phenomena, hysteretic curves and stiffness degradation of the composite structure were analyzed. Furthermore, effects of axial load ratio, aspect ratio, infill thickness and steel ratio on the share of horizontal force supported by the frame and the infill were obtained in the numerical example.

• Structural Engineering and Mechanics
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• v.38 no.2
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• pp.231-247
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• 2011

This study introduces a new load increment method for the ductile reinforced concrete (RC) frame structures by including strain-hardening effects. The proposed method is a nonlinear static analysis technique employed for RC frame structures subjected to constant gravity loads and monotonically increasing lateral loads. The material nonlinearity in RC structural elements is considered by adopting plastic hinge concept which is extended by including the strain hardening as well as interaction between bending moment and axial force. Geometric non-linearity, known as second order effect, is implemented to the method as well.

• Steel and Composite Structures
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• v.30 no.3
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• pp.253-269
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• 2019

This paper investigates the effects of the tensile catenary action on dynamic increase factor (DIF) in the nonlinear static analysis for progressive collapse of steel-frame buildings. Numerical analyses were performed to verify the accuracy of the empirical and analytical expressions proposed in the literature in cases where the catenary action is activated. For this purpose, nonlinear static and dynamic analyses of a series of steel moment frame buildings with a different number of spans and stories were carried out following the alternate path method. Different column removal scenarios were considered as separate load cases. The dynamic increase factor that approximately compensates for the dynamic effects in the nonlinear static analysis was selected so to match results from the nonlinear dynamic analysis. The study results showed that the many expressions in literature may not work in cases where the catenary stage is fully developed.

• Coupled systems mechanics
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• v.11 no.5
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• pp.373-387
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• 2022

In this paper,soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thicknessresting on bedrock. Amodified plane-strain numerical model isformed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacementsfor the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.

• Journal of Korean Association for Spatial Structures
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• v.6 no.1 s.19
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• pp.45-54
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• 2006

A steel frame is one of the most commonly used structural systems due to its resistance to various types of applied loads. Many studies have been conducted to investigate the effects of connection flexibility, support conditions, and beam-to-column stiffness ratio on the story drift of a frame. Based on the results of these studies, several design guides have been proposed. This research has been conducted to predict the actual behavior of a double angle connection, and to establish its effect on the story drift and the maximum allowable load of a steel frame. For these purposes, several experimental tests were conducted and a simplified analytical model was proposed. This simplified analytical model consists of four spring elements as well as a column member. In addition, a point bracing system was proposed to control the excessive story drift of an unbraced steel frame.