• Geomechanics and Engineering
• /
• v.21 no.1
• /
• pp.1-9
• /
• 2020

In this article, an analytical solution for the effect of the rotation on thermo-viscoelastic non-homogeneous medium with a spherical cavity subjected to periodic loading is studied. The distribution of displacements, temperature, redial stress, and hoop stress in non-homogeneous medium, in the context of generalized thermo-viscoelasticity using the GL theory, is discussed and obtained. The results are displayed graphically to illustrate the effect of the rotation. Comparisons with the previous work in the absence of rotation and viscosity are made.

• Structural Engineering and Mechanics
• /
• v.43 no.1
• /
• pp.53-70
• /
• 2012

Sliding cable joints have been developed for the cable dome structures and the suspen-dome structures to reduce the cable pre-stressing loss and obtain a uniform inner force in each hoop cable. However, the relevant investigation is less addressed on the structural behavior of the cable dome structures and the suspen-dome structures with sliding cable joints due to the lack of analysis techniques. In this paper, a closed sliding polygonal cable element was established to analyze the structural behavior of the cable dome structures and the suspen-dome structures with sliding cable joints. The structural behaviors with sliding cable joints were obtained.

• Computers and Concrete
• /
• v.13 no.2
• /
• pp.221-234
• /
• 2014

A nonlinear finite element analysis using ANSYS is used to evaluate the seismic behavior of reinforced concrete exterior beam-column joints. The behavior of the finite element models under cyclic loading is compared with the experimental results. Two beam-column joint specimens (SH and SHD) with square hoop confinement in joint and throughout the column with detailing as per IS 13920 are studied. The specimen SHD was provided with additional diagonal bars from column to beam to relocate the plastic hinge formation from beam-column interface. The load-displacement relationship, joint shear stress and strain in beam obtained from numerical study showed good agreement with the experimental results. This investigation proves that seismic behaviour of reinforced concrete beam-column joints under reversed cyclic loading can be evaluated successfully using finite element modeling and analysis.

• Journal of Ocean Engineering and Technology
• /
• v.19 no.1 s.62
• /
• pp.95-99
• /
• 2005

This paper presents the optimum design of cylindrical shell under external pressure loading. Two kinds of material, Al7075-T6, Ti-6Al-4V, are considered. For each material, the design variable is a thickness of the unstiffened parallel middle body shell, and the state variable, constraint, is hoop stress and the object .function is total weight of the cylindrical shell. Optimization is performed by conventional FE Program, ANSYS. In addition, buckling analysis is performed for the middle body of the cylindrical shell. Finally, we calculates the payload of the cylindrical shell to keep neutral buoyancy with optimized thickness in deep-sea applications.

• 한국기계연구소 소보
• /
• s.20
• /
• pp.49-55
• /
• 1990

Filament-Wound composite pressure vessels offer significant weight saving over the conventional metal pressure vessels. S-2 glass/epoxy pressure vessel was designed, fabricated and tested. It was considered, in the analysis that the matrix and the metal liner of FRP pressure vessel shared the internal pressure. The thicknesses of hoop and helical layers were determinded by the computer program developed for the design of FRP/Metal structural pressure vessel. The computer program increased the structural efficiency about 14% comparing with the netting analysis. The experimental measurement on the deformation by internal pressure agrees with the theoretical analysis within the accuracy of 5%.

• Steel and Composite Structures
• /
• v.24 no.6
• /
• pp.689-695
• /
• 2017

The constitutive relation is an important factor in analysis of confined concrete in composite structures. In order to propose a constitutive model for nonlinear analysis of confined concrete, lateral restraint mechanism of confined concrete is firstly analyze to study the generalities. As the foundation of the constitutive model, peak stress and peak strain is the first step in research. According to the generalities and the Twin Shear Unified Strength Theory, a novel unified equation for peak stress and peak strain are established. It is well coincident with experimental results. Based on the general constitutive relations and the unified equation for peak stress and peak strain, we propose a unified and convenient constitutive model for confined concrete with fewer material parameters. Two examples involved with steel tube confined concrete and hoop-confined concrete are considered. The proposed constitutive model coincides well with the experimental results. This constitutive model can also be extended for nonlinear analysis to other types of confined concrete.

• Structural Engineering and Mechanics
• /
• v.72 no.2
• /
• pp.155-168
• /
• 2019

This paper presents the results of an experimental investigation on the compressive strength of small scale concentrically axially loaded fiber-reinforced polymer (FRP) confined plain concrete columns, with cylinder concrete strength 19 MPa. For columns with circular (150-mm diameter) and square (150-mm side) cross sections wrapped with glass- and carbon-FRP sheets (GFRP and CFRP, respectively) applied with dry lay-up the effect of different jacket schemes and different overlap configurations on the confined characteristics is investigated. Test results indicate that the most cost effective jacket configuration among those tested is for one layer of CFRP, for both types of sections. In square sections the location of the lap length, either in the corner or along the side, does not seem to affect the confined performance. Furthermore, in circular sections, the presence of an extra wrap with FRP fibers parallel to the column's axis enhances the concrete strength proportionally to the axial rigidity of the FRP jacket. The recorded strains and the distributions of lateral confining pressures are discussed. Existing design equations are used to assess the lateral confining stresses and the confined concrete strength making use of the measured hoop strains.

• Structural Engineering and Mechanics
• /
• v.18 no.2
• /
• pp.151-166
• /
• 2004

The interaction between concrete core expansion and deformation of perimeter ties has been known to have a significant effect on the effective confinement of rectangular reinforced concrete (RC) tied columns. This interaction produces passive confining pressure to the concrete core. Most existing models for determining the response of RC tied columns do not directly account for the influence of flexural stiffness of the ties and the variation of confining stress along the column height. This study presents a procedure for determining the confined compressive strength of RC square columns confined by rectilinear ties with various tie configurations considering directly the influence of flexural flexibility of the ties and the variation of confining stress along the vertical direction. The concept of area compatibility is employed to ensure compatibility of the concrete core and steel hoop in a global sense. The proposed procedure yields satisfactory predictions of confined strengths compared with experimental results, and the influence of tie flexibility, tie configuration and degree of confinement can be well captured.

• Journal of Navigation and Port Research
• /
• v.26 no.3
• /
• pp.323-328
• /
• 2002

Soil-steel structures have been used for the underpass, or drainage systems in the road embankment. This type of structures sustain external load using the correlations with the steel wall and engineered backfill materials. Buried flexible conduits made of corrugated steel plates for the coastal road was tested under vehicle loading to investigate the effects of live load. Testing conduits was a circular structure with a diameter of 6.25m. Live-load tests were conducted on two sections, one of which an attempt was made to reinforce the soil cover with the two layers of geo-gird. Hoop fiber strains of corrugated plate, normal earth pressures exerted outside the structure, and deformations of structure were instrumented during the tests. This paper describes the measured static and dynamic load responses of structure. Wall thrust by vehicle loads increased mainly at the crown and shoulder part of the conduit. However additional bending moment by vehicle loads was neglectable. The effectiveness of geogrid-reinforced soil cover on reducing hoop thrust is also discussed based on the measurements in two sections of the structure. The maximum thrusts at the section with geogrid-reinforced soil cover was 85-92% of those with un-reinforced soil cover in the static load tests of the circular structure; this confirms the beneficial effect of soil cover reinforcement on reducing the hoop thrust. However, it was revealed that the two layers of geogrid had no effect on reducing the overburden pressure at the crown level of structure. The obtained values of DLA decrease approximately in proportion to the increase in soil cover from 0.9m to 1.5m. These values are about 1.2-1.4 times higher than those specified in CHBDC.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.6
• /
• pp.1125-1146
• /
• 2018

Segment lining applied to the TBM tunnel is mainly made of concrete, and it requires sufficient structural capacity to resist loads received during the construction and also after the completion. When segment lining is design to the Limit State Design, both Ultimate Limit State (ULS) and Service Limit State (SLS) should be met for the possible load cases that covers both permanent and temporary load cases - such as load applied by TBM. When design segment lining, it is important to check structural capacity at the joints as both temporary and permanent loads are always transferred through the segment joints, and sometimes the load applied to the joint is high enough to damage the segment - so called bursting failure. According to the various design guides from UK (PAS 8810, 2016), compression stress at the joint surface can generate bursting failure of the segment. This is normally from the TBM's jacking force applied at the circumferential joint, and the lining's hoop thrust generated from the permanent loads applied at the radial joint. Therefore, precast concrete segment lining's joints shall be designed to have sufficient structural capacity to resist bursting stresses generated by the TBM's jacking force and by the hoop thrust. In this study, bursting stress at the segment joints are calculated, and the joint's structural capacity was assessed using Leonhardt (1964) and FEM analysis for three different design cases. For those three analysis cases, hoop thrust at the radial joint was calculated with the application of the most widely used limit state design codes Eurocode and AASHTO LRFD (2017). For the circumferential joints bursting design, an assumed TBM jack force was used with considering of the construction tolerance of the segments and the eccentricity of the jack's position. The analysis results show reinforcement is needed as joint bursting stresses exceeds the allowable tensile strength of concrete. This highlights that joint bursting check shall be considered as a mandatory design item in the limit state design of the segment lining.