• Structural Engineering and Mechanics
• /
• v.65 no.1
• /
• pp.111-120
• /
• 2018

This paper presents a new and simple solution for determining the natural frequencies of framed tube combined with shear-walls and tube-in-tube systems. The novelty of the presented approach is based on the bending moment function approximation instead of the mode shape function approximation. This novelty makes the presented solution very simpler and very shorter in the mathematical calculations process. The shear stiffness, flexural stiffness and mass per unit length of the structure are variable along the height. The effect of the structure weight on its natural frequencies is considered using a variable axial force. The effects of shear lag phenomena has been investigated on the natural frequencies of the structure. The whole structure is modeled by an equivalent non-prismatic shear-flexural cantilever beam under variable axial forces. The governing differential equation of motion is converted into a system of linear algebraic equations and the natural frequencies are calculated by determining a non-trivial solution for the system of equations. The accuracy of the proposed method is verified through several numerical examples and the results are compared with the literature.

• Earthquakes and Structures
• /
• v.18 no.3
• /
• pp.321-335
• /
• 2020

The aim of the present contribution is to consider and underline the essential interactions among the historical knowledge, the seismic vulnerability assessment, the investigation experimental tools, the preservation of the architectural quality and the strengthening design in regard to architectural heritage conservation. These topics are argued in relation to Palazzo Murena in Perugia, designed in the eighteenth century by the famous Architect Luigi Vanvitelli, and currently headquarters of the city's University. Based on the surveys and the visual inspections, a preliminary a priori global analysis has been performed by means of the FME method. The obtained results permitted to plan an experimental tests campaign inclusive of structural health monitoring. The new achieved "knowledge" of the building allowed to refine the seismic safety assessment. In particular it was highlighted that the "mezzanine floor" can be a vulnerable element of the building with the collapse of its masonry walls. Preserving the architectural characteristics, a local reinforcement intervention is proposed for the above-mentioned level; this consists of the application of plaster with FRCM, assuring an adequate strength, without burden the masonry structure with additional weight, and therefore a decreasing of the seismic vulnerability. The necessity to consider, in this ongoing research, other local mechanisms is highlighted in the unfolding of the last part of work.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.6 no.6
• /
• pp.65-72
• /
• 2002

This study estimates steel house shear wall's seismic performance depending on trend of seismic design. As a result at cyclic-test, the capability of energy dissipation about X1SPCH during this test is good enough. The capability of energy dissipation of X3SPCH and X4SPCH was better than that of X1SPCH. The X2SPCH which is similar to real X-braced shear wall has better seismic performance than shear wall braced with structural sheathing materials on pseudo-dynamic test.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.918-923
• /
• 2003

Reinforced concrete deep beams are commonly used in many structural applications, including transfer girders, pile caps, foundation walls, and offshore structures. The existing design methods were developed and calibrated using normal strength concrete test results, and their applicability th HSC deep beams must be assessed. For the shear strength prediction of high-strength concrete(HSC) deep beams, this paper proposed Softened Strut-and-Tie Model(SSTM) considered HSC and bending moment effect. The shear strength predictions of the refined model, the formulas the ACI 318-02 Appendix A STM, and Eq. of ACI 318-99 11.8 are compared with the collected experimental data of 74 HSC deep beams with compressive strength in the range of 49-78MPa . It is shown the shear strength of deep beam calculated by those equations are conservative on comparing test results. The comparison shows that the performance of the proposed SSTM is better than the ACI Code approach for all the parameters under comparison. The parameters reviewed include concrete strength, the shear span-depth ratio, and the ratio of horizontal and vertical reinforcement. The proposed SSTM gave a mean predicted to experimental ratio of 0.99, 32 percent higher than ACI 318-02 Code, however with the low coefficient variation.

• Computers and Concrete
• /
• v.21 no.4
• /
• pp.441-449
• /
• 2018

FE models for complex or large-scaled structures that need detailed modeling of structural components are usually constructed using commercial analysis softwares. Updating of such FE model by conventional sensitivity-based methods is difficult since repeated computation for perturbed parameters and manual calculations are needed to obtain sensitivity matrix in each iteration. In this study, an FE model updating procedure avoiding such difficulties by using response surface (RS) method and a Pareto-based multiobjective optimization (MOO) was formulated and applied to FE models constructed with a commercial analysis package. The test building is a low-rise reinforced concrete building that has been seismically retrofitted. Dynamic properties of the building were extracted from vibration tests performed before and after the seismic retrofits, respectively. The elastic modulus of concrete and masonry, and spring constants for the expansion joint were updated. Two RS functions representing the errors in the natural frequencies and mode shape, respectively, were obtained and used as the objective functions for MOO. Among the Pareto solutions, the best compromise solution was determined using the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) procedure. A similar task was performed for retrofitted building by taking the updating parameters as the stiffness of modified or added members. Obtained parameters of the existing building were reasonably comparable with the current code provisions. However, the stiffness of added concrete shear walls and steel section jacketed members were considerably lower than expectation. Such low values are seemingly because the bond between new and existing concrete was not as good as the monolithically casted members, even though they were connected by the anchoring bars.

• Structural Engineering and Mechanics
• /
• v.75 no.2
• /
• pp.229-237
• /
• 2020

The steel slit shear wall (SSSW), made by cutting vertical slits in a steel plate, is increasingly used for the seismic protection of building structures. In the domain of thin plate shear walls, the out-of-plane buckling together with the potential fracture developed at slit ends at large lateral deformation may result in degraded shear strength and energy dissipation, which is not desirable in view of seismic design. To address this issue, the present study proposed a new type of SSSW made by intentionally introducing initial out-of-plane folding into the originally flat slitted plate. Quasi-static cyclic tests on three SSSWs with different amplitudes of introduced out-of-plane folding were conducted to study their shear strength, elastic stiffness, energy dissipation capacity and buckling behavior. By introducing proper amplitude of out-of-plane folding into the SSSW fracture at slit ends was eliminated, plumper hysteretic behavior was obtained and there was nearly no strength degradation. A method to estimate the shear strength and elastic stiffness of the new SSSW was also proposed.

• Journal of the Society of Disaster Information
• /
• v.9 no.4
• /
• pp.462-468
• /
• 2013

Walls for preventing floods using overturning or buoyancy method have been developed as replacement construction for preventing floods in and outside country. However, as they have some problems with pre-inspection and maintenance control, Eco-moving wall structure for preventing floods was studied and first developed using Glass Fiber Reinforced Composite which has not only light weight but outstanding strength. The developed wall structure for preventing floods offering structural stability and field applicability through numerical analysis was confirmed to reduce construction expenses by around 87~95% and secure waterproof property with the inside of the wall installed rubber water stopper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.125-130
• /
• 2014

High speed railroad car and high-rise apartment with development of railway technology cause different problems of noise contrary to the previous generation. It is the most efficient noise reduction countermeasure but we studied that is the way on noise propagation with sound proof wall or sound proof tunnel around railroad. But if it were railroad on bridge, additional cost which is more expensive than installing one on the ground is needed. So sound insulation material considering reducing weight of recent soundproof facilities must be selected. It is in this study that predicted and analyzed acoustical and structural effect for noise reduction by installing soundproof tunnel. If it were departmentalized into additional study, could be able to expect noise reduction effect of sound proof tunnel establishment on the bridge.

• KIEAE Journal
• /
• v.4 no.2
• /
• pp.65-72
• /
• 2004

Ecological architecture enables people to recycle and reuse architectural resources within the category of ecosystem and also to minimize the effect on environment in a whole process, including architectural planning, usage and exhaustion to use sustainable energies. Rammed earth wall construction method utilized in EcoCenter located in Crystalwaters ecological village in Austrailia is a good example, which maximizes its advantages and also covers its limits to use soil and wood as structural resources. In a case of wood, they used non-treated timber to minimize environmental load and utilized used materials in openings. In the roofs, aluminum coated steel which is plated with zinc collects rain effectively even though it is not regenerable. Nontoxic finishes and insulation in floor and ceiling with used papers are able to minimize its environmental load. Solar energy system applied in EcoCenter enables them to market extra energy with electricity companies as well as support needs of its own buildings to utilize photovoltaic panel system with PV panels. Passive solar system is planned effectively in heating and cooling to apply regenerative walls in a use of rammed earth wall construction and natural ventilation systems through openings.

• Journal of the Society of Naval Architects of Korea
• /
• v.40 no.6
• /
• pp.80-87
• /
• 2003

Tank structures in ships are in contact with various fluid. The vibration characteristics of those structures are strongly affected by the added mass due to containing fluid. It is important to predict vibration characteristics of tank structures, but it is difficult to do. That's because the interaction problem concerned with the free surface, the variation of water depth and stiffener is to be considered between the fluid and the structure. Many authors have studied vibration of rectangular tank structures containing water. Kito studied added mass effect of water in contact with thin elastic flat plates. Kim et al. studied flexural vibration of stiffened plates in contact with water. However, few researches on dynamic interaction tank walls with water are reported in the vibration of rectangular tanks recently. in the present report, the coupling effect of added mass of fluid and structural constraint between panels on each vibration mode changing breadth of elastic plate, and dynamic pressure distribution have investigated numerically and discussed.