• Computers and Concrete
• /
• v.1 no.3
• /
• pp.285-302
• /
• 2004

A FE-(FE-HE)-BE procedure is presented for dynamic analysis of concrete arch dams. In this technique, dam body is discretized by solid finite elements, while the reservoir domain is considered by a combination of fluid finite elements and a three-dimensional fluid hyper-element. Furthermore, foundation rock domain is handled by three-dimensional boundary element formulation. Based on this method, a previously developed program is modified, and the response of Morrow Point arch dam is studied for various conditions. Moreover, the effects of canyon shape on response of dam, is also discussed.

• Structural Engineering and Mechanics
• /
• v.78 no.5
• /
• pp.637-649
• /
• 2021

Great efforts have been conducted to investigate the seismic performances of the arch and rectangular underground structures, however, the differences between seismic responses of these two types of underground structures, especially the vault radian influencing the seismic responses of arch structures are not clarified. This paper presents a detailed numerical investigation on the seismic responses of arch underground structures with different vault radians, and aims to illustrate the rule that vault radian affects the seismic responses of underground structures. Five arch underground structures are built for nonlinear soil-structure interaction analysis. The internal forces of the structural components of the underground structures only under gravity are discussed detailedly, and an optimum vault radian for perfect load-carrying functionality of arch underground structures is suggested. Then the structures are analyzed under seven scaled ground motions, amounting to a total of 35 dynamic calculations. The numerical results show that the vault radian can have beneficial effects on the seismic response of the arch structure, compared to the rectangular underground structures, causing the central columns to suffer smaller axial force and horizontal deformation. The conclusions provide some directive suggestions for the seismic design of the arch underground structures.

• Advances in materials Research
• /
• v.12 no.1
• /
• pp.15-29
• /
• 2023

In this paper, fracture analysis of a continuously inhomogeneous arch structure with two longitudinal cracks is developed in terms of the time-dependent strain energy release rate. The arch under consideration exhibits non-linear creep behavior. The cross-section of the arch is a rectangle. The material is continuously inhomogeneous along the thickness of the cross-section. The arch is loaded by two bending moments applied at its end sections. The mechanical behavior of the material is described by using a non-linear stress-strain-time relationship. The two longitudinal cracks are located symmetrically with respect to the mid-span of the arch. Due to the symmetry, only half of the arch is considered. Time-dependent solutions to strain energy release rate are obtained by analyzing the balance of the energy. For verification, time-dependent solutions to the strain energy release rate are derived also by considering the time-dependent complementary strain energy. The evolution of the strain energy release rate with the time is analyzed. The effects of material inhomogeneity, locations of the two cracks along the thickness of the arch and the magnitude of the external loading on the time-dependent strain energy release rate are evaluated.

• Computers and Concrete
• /
• v.18 no.2
• /
• pp.179-199
• /
• 2016

The aim of this study is to investigate arrival direction effects of travelling waves on non-linear seismic response of arch dams. It is evident that the seismic waves may reach on the dam site from any direction. Therefore, this study considers the seismic waves arrive to the dam site with different angles, ${\theta}=0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$, and $90^{\circ}$ for non-linear analysis of arch dam-water-foundation interaction system. The N-S, E-W and vertical component of the Erzincan earthquake, on March 13, 1992, is used as the ground motion. Dam-water-foundation interaction is defined by Lagrangian approach in which a step-by-step integration technique is employed. The stress-strain behavior of the dam concrete is idealized using three-dimensional Drucker-Prager model based on associated flow rule assumption. The program NONSAP is employed in response calculations. The time-history of crest displacements and stresses of the dam are presented. The results obtained from non-linear analyses are compared with that of linear analyses.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.33 no.6
• /
• pp.391-399
• /
• 2020

In this study, the behaviors of a suction cap shaped as an arch were analyzed using finite element models. The fundamental structural behaviors of both flat- and arch-type caps were compared, and the advantages of the arch-shaped cap were explained. Moreover, the effects of geometric parameters and stiffener arrangements on the stress and deformation of the arch-shaped caps were investigated by comparisons of the changes in the behaviors of the caps. Additionally, the effects of boundary condition at the edge of the cap were analyzed to study the interactions between the cap and cofferdam walls; these results were used to derive the fundamental structural design of stiffened arch caps. Unlike flat caps, the results showed that ring stiffeners could improve the structural behaviors of arch caps remarkably, while the contributions of the radial stiffeners to the structural behaviors of the caps are dependent on constraints at the edges of the caps.

• The Journal of the Korean dental association
• /
• v.11 no.4
• /
• pp.277-280
• /
• 1973

The author observed the changes of dental arch dimensions and compared spae-maintainer group with non-space-maintainer group after primary tooth extraction. The results were as follows 1) The rate of growth of dental arch of expeirmental group in intercanine width and in inter-1st molar width was more rapid than that of the control group. 2) Arch length is almost no dimensions but it was slightly decreased in lower arch. 3) Dental arch growth and tooth eruption were stimulated by space-maintainer appliance, so it is the best way to replace a new appliance at least once a year. 4) It is thought that satisfactory conclusions in this observation must be researched successively until the mixed dentition completes.

• Structural Engineering and Mechanics
• /
• v.37 no.3
• /
• pp.321-330
• /
• 2011

Long-term properties of concrete affect structures in many respects, not excepting dynamic behaviors. This paper investigates the influence of concrete creep on the dynamic behaviors of concrete filled steel tube (CFT) arch bridges, by means of combining the analytical method for the creep of axially compressed CFT members, which is based on Model B3 for concrete creep, with the finite element model of CFT arch bridges. By this approach, the changes of the stress and strain of each element in the bridge with time can be obtained and then transformed into damping and stiffness matrices in the dynamic equation involved in the finite element model at different times. A numerical example of a long-span half-through CFT arch bridge shows that creep influences the natural vibration characteristics and seismic responses of the bridge considerably, especially in the early age. In addition, parameter analysis demonstrates that concrete composition, compressive strength and steel ratio have an obvious effect on the seismic response of the CFT arch bridge.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.1
• /
• pp.155-176
• /
• 2005

There is some evidence that one of major factors to produce plantar fasciitis depends on the magnitude of the foot arch strain. The orthotics that can reduce the foot arch strain during locomotion may be effective to prevent or treat plantar fasciitis. Therefore, the purpose of this study was to investigate the effect of control condition and three types of foot orthotics on 3-dimensional foot arch strain that can produce plantar fasciitis during treadmill level and uphill walking and running. Sixteen male subjects are recruited and the arch length and height strain according to three types of foot orthotics with respect to control condition were measured by using two digital video cameras. The first hypothesis which the comfort of foot orthotics would be increased from arch pad, half length orthotics to full length orthotics was mostly accepted. It suggested that the types of the foot orthotics could be properly prescribed according foot regions that is pain or abnormal. The second hypothesis which the foot arch strain can be reduced by foot orthotics during level heel-toe walking and running and the third hypothesis which the foot arch strain can be reduced by foot orthotics during uphill heel-toe walking and running were rejected. The foot arch length and height strain during walking and running showed small and subject-specific characteristics and could not be optimal biomechanical variable to prove the overall comfort. The forth hypothesis which the foot arch strain cannot be reduced by foot orthotics during uphill toe walking and running was accepted. With the foot arch length and height strain during uphill toe walking and running the windlass mechanism suggested by Hicks can be explained successfully and excessive uphill toe walking and running can be one of cause of plantar fasciitis. The dynamic investigation on the foot arch such as walking and running should be carefully observed with integrated insights considering ligaments and foot bones as well as plantar fascia, extrinsic muscles and tendons, and intrinsic muscles and tendons.

• Korean Journal of Applied Biomechanics
• /
• v.20 no.1
• /
• pp.91-99
• /
• 2010

The purpose of this study was to the kinetic variables effects from the use of arch support inserts on low-arched people. We selected 10 people for the research and separated them into 2 groups, 5 people for the normal arched group and 5 people for the low arched group. Each group wear shoes which have a 3 step convertible arch support (level 0, level 2, level 5) and we measured their foot pressure and 3D motion analysis data. As a result, we found that the mean pressure at the heel of the low arched group was decreased when using the arch supports. The arch support induced the correct grounding area for the foot and dispersion of foot pressure. 3D motion analysis found that as the height of the arch support was increased, the movement of the Y-axis(inversion-eversion) was increased to relieve the shock to the heel. The arch support insert limited the range of motion(ROM) of the Z-axis(abduction-adduction) of the low arched person's ankle joint and prevented ankle injury caused by the excessive eversion when walking. Low arched people are seen to be easily tired due to the ineffective shock absorption of the knees and abnormal walking motion. In order to improve the problems, a 3 step convertible arch support(level 5) insert would improve the low-arched people's walking ability. In other words, the low arched people should be expected to walk as well as normal arched people when they wear shoes with the arch support insert.

• Steel and Composite Structures
• /
• v.23 no.2
• /
• pp.187-194
• /
• 2017

To reuse a broken plain concrete (PC) arch, a retrofitting method was proposed to ensure excellent structural performances, in which carbon fiber reinforced polymers (CFRPs) were applied to repair and strengthen the damaged PC arch through bonding and wrapping techniques. Experiments were carried out to reveal the deformation and the load carrying capacity of the retrofitted composite arch. Based on the experiments, repairing and strengthening effects of the CFRP retrofitted broken arch were revealed. Simplified analysing model was suggested to predict the peak load of the CFRP retrofitted broken arch. According to the research, it is confirmed that absolutely broken PC arch can be completely repaired and reinforced, and even behaves more excellent than the intact PC arch when bonded together and strengthened with CFRP sheets. Using CFRP bonding/wrapping technique a novel efficient composite PC arch structure can be constructed, the comparison between rebar reinforced concrete (RC) arch and composite PC arch reveals that CFRP reinforcements can replace the function of steel bars in concrete arch.