• Journal of International Academy of Physical Therapy Research
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• v.10 no.3
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• pp.1840-1848
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• 2019

Background : There is lack of studies on the effects of the bag-carrying style on the shoulder muscles and body alignment in adults with rounded shoulder posture (RSP). Objective: The purpose of this study was to investigate the effects of various bag-carrying styles on muscle tone, muscle stiffness and spinal alignment in 20 adults with RSP as they were walking on a treadmill. Design : Crossover Study Design. Methods: A subject performed treadmill walking for 15 minutes at a speed of 4 ㎞/ｈ while carrying three different types of bags: a backpack, a cross bag, and a shoulder bag. Results : The results showed that the main effect of timing was observed in the muscle tone for all the variables and in muscle stiffness only for the upper and lower trapezius muscles. As for the main effect of timing, the muscle tone of the upper trapezius and the pectoralis major significantly increased in all conditions, while the muscle tone of the lower trapezius significantly decreased in all conditions. The muscle stiffness of the upper trapezius significantly increased in all conditions, while the muscle stiffness of the lower trapezius significantly decreased in all conditions. As for the spinal alignment, the dimple distance data values significantly decreased for the cross-bag style. Conclusions : This study demonstrated that walking with a heavy bag, regardless of the bag-carrying style, increased muscle stiffness around the shoulders in adults with rounded shoulder posture, and walking with a cross-bag also induced changes in spinal alignment.

• Steel and Composite Structures
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• v.39 no.4
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• pp.419-433
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• 2021

In composite structures, shear connectors are crucial components to resist the relative slip between the steel and concrete, and thereby to achieve the composite actions. In the service stage, composite structures are usually in elastic state, so the elastic stiffness of the shear connection is a quite important parameter in the structural analysis of composite structures. Nevertheless, the existing studies mainly focus on the load-slip relationship rather than the tangent stiffness at the initial elastic stage. Furthermore, when composite beams subjected to torque or local load, shear connections are affected by both tensile force and shear force. However, the stiffness of shear connections under combined effects appears not to have been discussed hitherto. This paper investigates the initial elastic stiffness of stud connections under combined effects of biaxial forces. The initial expression and the relevant parameters are obtained by establishing a simplified analytical model of the stud connection. Afterwards, parametric finite element analysis is performed to investigate the effects of the relevant factors, including the stud length, stud diameter, elastic modulus of concrete, elastic modulus of steel and volume ratio of reinforcement. The feasibility of the proposed modelling has been proved by comparing with sufficient experimental tests. Based on the analytical analysis and the extensive numerical simulations, design equations for predicting the initial elastic stiffness of stud connections are proposed. The comparison between the equations and the data of finite element models demonstrates that the equations are accurate enough to serve for engineering communities.

• Structural Engineering and Mechanics
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• v.88 no.1
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• pp.43-52
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• 2023

This paper handles the results of an extensive parametric study on the rotational stiffness of the flexible base connection using ABAQUS program. The results of the parametric study show the relation between the applied moment and the relative rotation for 96 different base connections. The configurations of the studied connections considered different numbers, diameters, and spacing of the anchor bolts along with different thicknesses of the base plate to investigate the effect of these parameters on the rotational stiffness behavior. The results of the previous parametric research used through the whale optimization algorithm (WOA) to detect different equation formulation of the moment-rotation (M-Ɵ_r) equation to detect optimum equation simulates the general nonlinear rotational behavior of the flexible base connection considering all variables used in the parametric study. WOA is a relatively new promising algorithm, which is used in different types of optimization problems. For more verification, the classical genetic algorithm (GA) is used to make a comparison with WOA results. The results show that WOA is capable of getting an optimum equation of the M-Ɵ_r relation, which can be used to simulate the actual rotational stiffness of the flexible base connections. The rotational stiffness at H/150 can be calculated using WOA (1) method and be used as a design aid for engineering design.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1406-1416
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• 2008

Soil nailing is used as a method of slope stabilization and excavation support. The design method of soil nail are based on experience or assumption of interaction between soil and reinforcement. Most design methods simply considers the tension of reinforcement for analysis of slope stabilization. Soil nails interact with soils under combined loading of shear and tension. Jewell & Pedley(1990) suggested a design equation of shear force with bending stiffness and discussed that the magnitude of the maximum shear force is small in comparison with the maximum axal force. However, they have used a very conservative limiting bearing stress on nails. This paper discusses that the shear strength of soil nails should not be disregarded with proper bearing stresses on nails. The modified FHWA design method was proposed by considering shear forces on nails with bending stiffness.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.68-78
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• 2003

Recently, low speed vehicle (LSV) is beginning to appear for various usages. The body of the LSV is usually made of the aluminum space frame (ASF) type rather than the monocoque or unitary construction type. A pa.1 of the reason is that it is easier to reduce mass efficiently while the required stiffness and strength are maintained. A design flow for LSV is proposed. Design specifications for structural performances of LSV do not exist yet. Therefore, they are defined through a comparative study with general passenger automobiles. An optimization problem is formulated by the defined specifications. At first, one pillar which has an important role in structural performances is selected and the reinforcements of the pillar are determined from topology optimization to maximize the stiffness. At second, the thicknesses of cross sections are determined to minimize the mass of the body while design specifications are satisfied. The optimum solution is compared with an existing design. The optimization process has been performed using a commercial optimization software system, GENESIS 7.0.

• Steel and Composite Structures
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• v.47 no.3
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• pp.375-382
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• 2023

The H-shaped steel beam is popular due to its ease of manufacturing and connection to the column. This profile, which is used as a shallow beam, needs the high weak-axis bending stiffness and torsional stiffness to meet the overall stability. Achieving the local beam flange stability, bearing capacity, bending stiffness, and torsional requirements need a great thickness and width of the beam flange, which causes, which will cause more uneconomical structural design. So, the box-section beam is the ideal alternative. However, the current design specifications do not have design rules for the bolt-and-welded connection of the box-section beam and box-section column. The paper proposes a novel bolt-and-welded connection of the box-section beams and box-section columns based on a high-rise structural design scheme. Three connection models, BASE, WBF, and RBS, are analyzed under cyclic loading in ABAQUS software. The failure modes, hysteresis response, bearing capacity, ductility, plastic rotation angle, energy dissipation, and stiffness degradation of all models are determined and compared. Compared with the other two models, the model WBF exhibited excellent seismic performance, ductility, and plastic rotation ability. Finally, model WBF was chosen as the connection scheme used in the project design.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.33-41
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• 1994

The procedure to design the engine mount is briefly discussed and the optimum shape design process of engine mounting rubber using a parametric approach is suggested. An optimization code is developed to determine the shape to meet the stiffness requirements of engine mounts, coupled with the commercial nonlinear finite element program ABAQUS. A bush type engine mount used in a current passenger car is chosen for an application model. The shape from the result of the parameter optimization is determined as a final model with some modifications. The shape and stiffness of each optimization stage are shown and the stiffness of the optimized model along the principal direction is compared with the design specification of the current model. Finally, an overview of the current status and future works for the engine mount design are discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.477-478
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• 2006

This paper presents the results of miniaturized micro milling machine tool development for micro precision machining process. Finite element analysis has been performed to know the relationship between design dimensional variables and structural stiffness in terms of static, dynamic, thermal aspects. Design optimization has been performed to optimize the design variables of micro machine tool to minimize the volume, weight and deformation of machine tool structure and to maximize the stiffness in terms of static, dynamic, and thermal characteristics. This study presents the assessment of the technology incentive for the minimization of machine tool in the quantitative context of static, dynamic stiffness, thermal resistance and thus the accuracy implications.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.314-321
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• 1998

This paper presents motion based design methodology for structures. Current design methodologies are primarily strength-based. Such methods are adequate when strength is expected to govern the design. But as the slenderness of structures increases, motion such as displacement and acceleration becomes the dominant criterion. In this paper, a preliminary design approach for beam-type buildings, where motion dominates the design, is discussed by effectively distributing the magnitude of structural stiffness to control the distribution of displacement under service load. This analytic development is illustrated using a cantilever beam as the structure under static loads, free vibration, and forced vibration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.1-11
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• 1993

Precast/Prestressed concrete segmental bridges with moderate range of span length normally have a constant section height for economic segment manufacturing. Inside sectional dimension is often controlled for design of non-prismatic section between supports when variable stiffness is required. It is usual, in the preliminary design stage, to adopt trial bridge sections by past experience or by approximately estimated member forces. Three bridge models of different member stiffness have been selected to investigate flexural stiffness effects on member forces for preliminary design stage. The selected bridge stiffness has been determined by the flexibility index from review of the practically usable sections.