• Steel and Composite Structures
• /
• v.34 no.6
• /
• pp.891-907
• /
• 2020

Many studies reveal that during destructive earthquakes, most of the structures enter the inelastic phase. The amount of hysteretic energy in a structure is considered as an important criterion in structure design and an important indicator for the degree of its damage or vulnerability. The hysteretic energy value wasted after the structure yields is the most important component of the energy equation that affects the structures system damage thereof. Controlling this value of energy leads to controlling the structure behavior. Here, for the first time, the hysteretic behavior and energy dissipation capacity are assessed at presence of elliptical braced resisting frames (ELBRFs), through an experimental study and numerical analysis of FEM. The ELBRFs are of lateral load systems, when located in the middle bay of the frame and connected properly to the beams and columns, in addition to improving the structural behavior, do not have the problem of architectural space in the bracing systems. The energy dissipation capacity is assessed in four frames of small single-story single-bay ELBRFs at ½ scale with different accessories, and compared with SMRF and X-bracing systems. The frames are analyzed through a nonlinear FEM and a quasi-static cyclic loading. The performance features here consist of hysteresis behavior, plasticity factor, energy dissipation, resistance and stiffness variation, shear strength and Von-Mises stress distribution. The test results indicate that the good behavior of the elliptical bracing resisting frame improves strength, stiffness, ductility and dissipated energy capacity in a significant manner.

• Structural Engineering and Mechanics
• /
• v.11 no.3
• /
• pp.287-299
• /
• 2001

Columns in multi-storey frames are presently categorised as either braced or unbraced, usually by means of the stability index criterion, for estimating their effective length ratios by design aids such as 'alignment charts'. This procedure, however, ignores the transition in buckling behaviour between the braced condition and the unbraced one. Hence, this results in either an overestimation or an underestimation of effective length estimates of columns in frames that are in fact 'partially braced'. It is shown in this paper that the transitional behaviour is gradual, and can be approximately modelled by means of a 'fuzzy logic' based technique. The proposed technique is simple and intuitively agreeable. It fills the existing gap between the braced and unbraced conditions in present codal provisions.

• Journal of Chest Surgery
• /
• v.45 no.6
• /
• pp.396-400
• /
• 2012

Background: Surgery has been the classical treatment of pectus carinatum (PC), though compressive orthotic braces have shown successful results in recent years. We propose a non-operative approach using a lightweight, patient-controlled dynamic chest-bracing device. Materials and Methods: Eighteen patients with PC were treated between July 2008 and June 2009. The treatment involved fitting of the brace, which was worn for at least 20 hours per day for 6 months. Their degree of satisfaction (1, no correction; 4, remarkable correction) was measured at 12 months after the initiation of the treatment. Results: Thirteen (72.2%) patients completed the treatment (mean time, $4.9{\pm}1.4$ months). In patients who completed the treatment, the mean overall satisfaction score was $3.73{\pm}0.39$. The mean satisfaction score was 4, and there was no recurrence of pectus carinatum in patients who underwent the treatment for at least 6 months. Minimal recurrence of pectus carinatum after removal of the compressive brace occurred in 5 (38.5%) patients who stopped wearing the compressive brace at 4 months. Conclusion: Compressive bracing results in a significant improvement in PC appearance in patients with an immature skeleton. However, patient compliance and diligent follow-up appear to be paramount for the success of this method of treatment. We currently offer this approach as a first-line treatment for PC.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.1
• /
• pp.131-138
• /
• 2006

Structural bracing concept equipped with a new and efficient friction based energy dissipation device is referred to Friction SliP Brace (FSB) where the behavior of the brace components is elastic until the axial resistant force in the brace exceeds the friction force developed at the frictional interface of the device. In this study, the FSB concept is modified and new type of hybrid energy dissipation device, the Active Friction SliP Braces (AFSB), is described. The FSB is by far improved in the AFSB by inclusion of an active clamping mechanism on the friction interface. The clamping action regulated by the developed algorithm is altered during the response of the building. The results indicate that the action of dissipating vibrational energy in the AFSB impacts on the response at later cycles by keeping the drift amplitudes at much lower levels, revealing overshooting problem due to its early slippage. Providing predetermined constant incremental strengths to the building by AFSB medium improves response by reducing drift amplitudes and base shear under small and medium amplitude ground accelerations.

• Earthquakes and Structures
• /
• v.4 no.2
• /
• pp.219-239
• /
• 2013

The present paper aims at studying the seismic response of structures equipped with viscoelastic dampers (VED). The performance of such a passive control system is here analyzed using the energy balance concept, which leads to an optimal design process. The methodology is based on an energy index (EDI) whose maximization permits determination of the optimal mechanical characteristics of VED. On the basis of a single degree of freedom model, it is shown that the maximum value of EDI corresponds to a simultaneous optimization of the significant kinematic and static response quantities, independently of the input. By using the proposed procedure, the optimal design of new and existing structures equipped with VED, inserted in traditional bracing systems, are here analyzed and discussed.

• Steel and Composite Structures
• /
• v.20 no.2
• /
• pp.431-445
• /
• 2016

Seismic behavior of new composite structural system with a fabricated floor was studied. A two-bay and three-story structural model with the scale ratio of 1/4 was consequently designed. Based on the proposed model, multiple factors including energy dissipation capacity, stiffness degradation and deformation performance were analyzed through equivalent single degree of freedom pseudo-dynamic test with different earthquake levels. The results show that, structural integrity as well as the effective transmission of the horizontal force can be ensured by additional X bracing at the bottom of the rigidity of the floor without concrete topping. It is proved that the cast-in-place floor in areas with high seismic intensity can be replaced by the prefabricated floor without pouring surface layer. The results provide a reliable theoretical basis for the seismic design of the similar structural systems in engineering application.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.10a
• /
• pp.3-10
• /
• 2002

Recently, arches are used structurally because of their high in-plane stiffness and strength, which result from their ability to transmit most of the applied loading by axial forces actions, so that the bending actions are reduced. On the other hand, the resistances of arches to (out-of-plane,) flexural-torsional behavior depend on the rigidities EI/sub y/, for lateral bending, GJ for Uniform torsion, and EI/sub w/ for warping torsion which are related to axial stress for flexural-torsional behavior. The resistance of an arch to out-of-plane behavior may be reduced by its in-plane curvature, and so it may require significant lateral bracing. Thus. it is supposed that In-plane preloading which cause an axial stress, have an effect on out-of-plane free vibration behavior of arches. Because axial stresses caused increase or decrease out-of-plane stiffness. But study about this substance is insufficient. In this thesis, We will study an effect of preloading on lateral free vibration of arches, using finite element method based on Kang and Yoo's curved beam theory (about curved beam element have 7 degree of freedom including warping) with FORTRAN programming.

• Journal of Korean Foot and Ankle Society
• /
• v.10 no.2
• /
• pp.247-249
• /
• 2006

Purpose: The neural injuries by the sprain around the ankle joint may contribute the chronic pain. Authors analyzed the incidence and the contributing factor of the neural injuries in ankle sprain. Materials and Methods: 52 patients (54 cases) were involved in this retrospective study. Patient with diabetes or spinal disease were excluded. Plain radiograph and MR image were evaluated. Treatments were consisted of cast immobilization for 4 weeks with weight bearing ambulation following bracing for 8 weeks. Neurologic evaluation were performed at 3 months, 6 months, 12 months post-injury period and each neural injury were confirmed by electromyography or lidocaine block test. Results: The average age was 39 years old and 34 cases were male and 20 cases were female. Rupture of the anterior talofibular ligament was observed in 48 cases, distal anterior tibiofibular ligament in 37 cases, calcaneofibular ligament in 6 cases. One cases revealed no injury of the ligament. Neural injuries around ankle was observed in 13 cases ; superficial peroneal nerve in 9 cases, sural nerve in 5 cases, saphanous nerve in 1 case. Neural injury was not influenced by the degree of ligament injuries but by the incidence numbers of ankle sprain. All cases were treated conservatively and symptom was subsided in all but 2 cases. Conclusion : Although the incidence is relatively low, the neural injuries in ankle sprain may occur in the recurrent ankle sprain and conservative treatment for neural injuries is satisfactory.

• Journal of the Korean Society of School Health
• /
• v.10 no.2
• /
• pp.241-257
• /
• 1997

This study identifies a basic framework to analyze specific experiences of examinees so that which nurses are better able to understand reactions of examinees and, further, to provide better nursing treatments to them. This study follows Strauss & Corbin's analysis tool (1990). This basic framework identifies the specific mental reactions in a process away from the "being tightened" state. The main factors explaining this process include the 28 following variables : anxiety, being burdened, being suppressed, lack of agency, being suffocated, term pressure, expectation pressure, grade pressure, firmness, feebleness, helping others, being disturbed, watching others, off ficiousness, staightening on, depending on, getting along with, getting out of, shooting out, giving up, being alone, devoting, bracing up, being industrious, being harassed, being distressed, troubles, and quiting. Twelve variables are factored from the above factors which include pressure, being tighened, terms, expectations, grades, will, friends, family, open-minded confrontation, close-minded confrontation, pursuing, and wandering around. The Examinees' state of being tightened is first developed, watched by others, and finally resolved causing students either to pursue (positive reactions) or to wander around (negative reactions). Based on the theoretical framework, the following sixteen hypotheses are developed : 1. Students are less tightened in the first term. 2. Students are more tightened in the second term. 3. Students with higher grades feel less tightened. 4. Students with lower grades feel more tightened. 5. Students with higher expectations feel more tightened. 6. Students with lower expectations feel less tightened. 7. Students who are less tightened confront open-mindedly. 8. Students who are higher tightened confront close-mindedly. 9. Students with a strong will confront open-mindedly. 10. Students with a weak will confront close-mindedly. 11. Students who have more sincere friends confront open-mindedly. 12. Students who have less sincere frieds confront close-mindedly. 13. Students with family support confront open-mindedly. 14. Students with little family support confront close-mindedly. 15. Students confronting open-mindedly pursue. 16. Students confronting close-mindedly wander. We identify the following four relations from the data analysis : 1. Students with average grades in their first term are more tightened from high expectations and have a tendency to wander if they have less supporting families even if they also have a strong will and sincere friends. 2. Students with low grades in their second term are less tighened because of low expectations and have a tendency to wander if they have a weak will and few sincere friends even if they have strong family support. 3. Students with high grades in their second term are more tightened with high expectations and have a tendency to pursue confrontations open-mindedly if they have supporting families and a strong will even if they have few sincere friends. 4. Students with average grades in their first term are less tightened from fewer expectations and have a tendency to pursue confrontations open-mindedly when they have more supporting families and sincere friends even if they have a weak will. A Student's degree of being tightened are affected by grades, terms, and expectations. Being tightened is resolved positively or negatively based on will, friends, and family. We conclude that will, family support, and sincere friends cause students to confront "being tightened" open-mindedly. We also conclude that practical nursing for students who are tightened have to focus on creating environments in which students are able to confront open-mindedly.