• 국제초고층학회논문집
• /
• 제2권2호
• /
• pp.141-152
• /
• 2013

This paper presents a brief overview of the recently developed performance-control method of moment frame design subjected to monotonously increasing lateral loading. The final product of any elastic-plastic analysis is a nonlinear loaddisplacement diagram associated with a progressive failure mechanism, which may or may not be as desirable as expected. Analytically derived failure mechanisms may include such undesirable features as soft story failure, partial failure modes, overcollapse, etc. The problem is compounded if any kind of performance control, e.g., drift optimization, material savings or integrity assessment is also involved. However, there is no reason why the process can not be reversed by first selecting a desirable collapse mechanism, then working backwards to select members that would lead to the desired outcome. This article provides an overview of the newly developed Performance control methodology of design for lateral resisting frameworks with a view towards integrity control and prevention of premature failure due to propagation of plasticity and progressive P-delta effects.

• Wind and Structures
• /
• 제11권2호
• /
• pp.153-178
• /
• 2008

Based on the empirical formulas for power spectra of generalized modal forces and local fluctuating wind forces in across-wind and torsional directions, the wind-induced lateral-torsional coupled response analysis of a representative rectangular tall building was conducted by setting various parameters such as eccentricities in centers of mass and/or rigidity and considering different torsional to lateral stiffness ratios. The eccentricity effects on the lateral-torsional coupled responses of the tall building were studied comprehensively by structural dynamic analysis. Extensive computational results indicated that the torsional responses at the geometric center of the building may be significantly affected by the eccentricities in the centers of mass and/or rigidity. Covariance responses were found to be in the same order of magnitude as the along-wind or across-wind responses in many eccentricity cases, suggesting that the lateral-torsional coupled effects on the overall wind-induced responses can not be neglected for such situations. The calculated results also demonstrated that the torsional motion contributed significantly to the total responses of rectangular tall buildings with mass and/or rigidity eccentricities. It was shown through this study that the framework presented in this paper provides a useful tool to evaluate the wind-induced lateral-torsional coupled responses of rectangular buildings, which will enable structural engineers in the preliminary design stages to assess the serviceability of tall buildings, potential structural vibration problems and the need for a detailed wind tunnel test.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권5호
• /
• pp.249-256
• /
• 2000

This paper deals with the control of the lateral motion of a mobile vehicle. A mobile vehicle using in this experiment is able to adapt many unmanned automatic driving system, for example, like a automated product transporting system. This vehicle is consist of the two servomotors. One is used to accelerate this vehicle and the another is used to change this lateral direction. An adaptive fuzzy logic controller(AFLC) is designed and applied to a experimental mobile vehicle in order to achieve the control of the lateral direction. An adaptive fuzzy logic controller(AFLC) is designed and applied to a experimental mobile vehicle in order to achieve the control of the lateral motion of the vehicle. Therefore, the main aim of this paper is investigate the possibility of applying adaptive fuzzy control algorithms to a microprocessor-based servomotor controller which requires faster and more accurate response compared with many other industrial processes. Fuzzy control rules are derived by modelling an expert's driving actions. Experiments are performed using a mobile vehicle with sensing units, a microprocessor and a host computer.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
• /
• pp.170-177
• /
• 2000

Recently many high-rise apartment buildings are constructed using the box system which is composed only of concrete walls and slabs. Commercial softwares such as ETABS used for the analysis of high-rise apartment buildings are employing the rigid diaphragm assumption for simplicity in the analysis procedure. In general the flexural stiffness of floor slabs are ignored in the analysis, This assumption may be reasonable for the estimation of seismic response of framed structures. But in the case of the box system used in the apartment buildings floor slabs has major effects on the lateral stiffness of the structure. So if the flexural stiffness of slabs in the box system is ignored the lateral stiffness may be significantly underestimated, For these reasons it is recommended to use plate elements to represent the floor slabs. In the study A typical frame structure and a box system structure are chosen as the example structure. When a 20 story frame structure is subjected to the static lateral loads the displacements of the roof are 15.33cm and 17.52cm for the cases with and without the flexural stiffness of the floor slabs. And in case of box system the roof displacement was reduced from 16.18cm to 8.61cm The model without the flexural stiffness of floor slabs turned out to elongate the natural periods of vibration accordingly.

• Interaction and multiscale mechanics
• /
• 제5권1호
• /
• pp.57-73
• /
• 2012

The paper presents the analysis of two groups of piles subjected to lateral loads incorporating the non-linear behaviour of soil. The finite element method is adopted for carrying out the parametric study of the pile groups. The pile is idealized as a one dimensional beam element, the pile cap as two dimensional plate elements and the soil as non-linear elastic springs using the p-y curves developed by Georgiadis et al. (1992). Two groups of piles, embedded in a cohesive soil, involving two and three piles in series and parallel arrangement thereof are considered. The response of the pile groups is found to be significantly affected by the parameters such as the spacing between the piles, the number of piles in a group and the orientation of the lateral load. The non-linear response of the system is, further, compared with the one by Chore et al. (2012) obtained by the analysis of a system to the present one, except that the soil is assumed to be linear elastic. From the comparison, it is observed that the non-linearity of soil is found to increase the top displacement of the pile group in the range of 66.4%-145.6%, while decreasing the fixed moments in the range of 2% to 20% and the positive moments in the range of 54% to 57%.

• 한국정밀공학회지
• /
• 제23권2호
• /
• pp.104-112
• /
• 2006

The influence of tire belt angle on the Plysteer Residual Aligning Torque(PRAT) and the cornering stiffness by the FEM has been studied. The PRAT is a performance factor of the tire about vehicle pull, and the cornering stiffness has relation to vehicle steering response of outdoor test. To validate FE model for analysis, simulation data for both the static stiffness(vertical, lateral) and the PRAT have been compared with the experimental data. In addition to the characteristics of the PRAT and the cornering stiffness due to the tire belt angle, rolling and cornering contact characteristics have been studied. The tendency of the PRAT and the cornering stiffness due to the belt angle can be used as a guide line for the tire design in relation to vehicle pull and vehicle steering response.

• Earthquakes and Structures
• /
• 제11권1호
• /
• pp.141-163
• /
• 2016

Fiber models have been developed and applied to various structural elements such as shear walls, beams and columns. Only scarcely have fiber models been applied to circular foundation systems such as cast in drilled holes shafts (CIDH). In pile foundations with constraint head boundary conditions, shear deformations can easily contribute to the lateral pile response. However, soil structure interaction formulations such as the p-y method, commonly used for lateral pile design, do not include structural shear deformations in its traditional derivation method. A fiber model that couples shear and axial-bending behavior, originally developed for wall elements was modified and validated on circular cross sections (columns) before being applied to a 0.61 m diameter reinforced concrete (RC) pile with fixed head boundary conditions. The analytical response was compared to measured test results of a fixed head test pile to investigate the possible impact of pile shear deformations on the displacement, shear, and moment profiles of the pile. Results showed that shear displacements and forces are not negligible and suggest that nonlinear shear deformations for RC piles should be considered for fixed-head or similar conditions. Appropriate sensor layout is recommended to capture shear deformation when deriving p-y curves from field measurements.

• Earthquakes and Structures
• /
• 제7권5호
• /
• pp.667-689
• /
• 2014

Structural walls (also known as shear walls) are one of the common lateral load resisting elements in reinforced concrete (RC) buildings in seismic regions. The performance of RC structural walls in recent earthquakes has exposed some problems with the existing design of RC structural walls. The main issues lie around the buckling of bars, out-of plane deformation of the wall (especially the zone deteriorated in compression), reinforcement getting snapped beneath a solitary thin crack etc. This study compares performance of a typical wall designed by different standards. For this purpose, a case study RC shear wall is taken from the Hotel Grand Chancellor in Christchurch which was designed according to the 1982 version of the New Zealand concrete structures standard (NZS3101:1982). The wall is redesigned in this study to comply with the detailing requirements of three standards; ACI-318-11, NZS3101:2006 and Eurocode 8 in such a way that they provide the same flexural and shear capacity. Based on section analysis and pushover analysis, nonlinear responses of the walls are compared in terms of their lateral load capacity and curvature as well as displacement ductilities, and the effect of the code limitations on nonlinear responses of the different walls are evaluated. A parametric study is also carried out to further investigate the effect of confinement length and axial load ratio on the lateral response of shear walls.

• Earthquakes and Structures
• /
• 제14권6호
• /
• pp.525-535
• /
• 2018

This study presents a new beam-column model comprising material nonlinearity and joint flexibility to predict the nonlinear response of reinforced concrete structures. The nonlinear behavior of connections has an outstanding role on the nonlinear response of reinforced concrete structures. In presented research, the joint flexibility is considered applying a rotational spring at each end of the member. To derive the moment-rotation behavior of beam-column connections, the relative rotations produced by the relative slip of flexural reinforcement in the joint and the flexural cracking of the beam end are taken into consideration. Furthermore, the considered spread plasticity model, unlike the previous models that have been developed based on the linear moment distribution subjected to lateral loads includes both lateral and gravity load effects, simultaneously. To confirm the accuracy of the proposed methodology, a simply-supported test beam and three reinforced concrete frames are considered. Pushover and nonlinear dynamic analysis of three numerical examples are performed. In these examples the nonlinear behavior of connections and the material nonlinearity using the proposed methodology and also linear flexibility model with different number of elements for each member and fiber based distributed plasticity model with different number of integration points are simulated. Comparing the results of the proposed methodology with those of the aforementioned models describes that suggested model that only uses one element for each member can appropriately estimate the nonlinear behavior of reinforced concrete structures.

• Steel and Composite Structures
• /
• 제18권6호
• /
• pp.1569-1582
• /
• 2015

This study explores the lateral deflections of diagonal braces in concentrically-braced earthquake-resisting frames. The performance of this widely-used system is often compromised by the flexural buckling of slender braces in compression. In addition to reducing the compressive resistance, buckling may also cause these members to undergo sizeable lateral deflections which could damage surrounding structural components. Different approaches have been used in the past to predict the mid-length lateral deflections of cyclically loaded steel braces based on their theoretical deformed geometry or by using experimental data. Expressions have been proposed relating the mid-length lateral deflection to the axial displacement ductility of the member. Recent experiments were conducted on hollow and concrete-filled circular hollow section (CHS) braces of different lengths under cyclic loading. Very slender, concrete-filled tubular braces exhibited a highly ductile response, undergoing large axial displacements prior to failure. The presence of concrete infill did not influence the magnitude of lateral deflection in relation to the axial displacement, but did increase the number of cycles endured and the maximum axial displacement achieved. The corresponding lateral deflections exceeded the deflections observed in the majority of the previous experiments that were considered. Consequently, predictive expressions from previous research did not accurately predict the mid-height lateral deflections of these CHS members. Mid-length lateral deflections were found to be influenced by the member non-dimensional slenderness (${\bar{\lambda}}$) and hence a new expression was proposed for the lateral deflection in terms of member slenderness and axial displacement ductility.