Compression Brace Research Articles

圧縮抵抗型CFTブレースにより耐震補強したRC造建物の地震応答性状に関する解析的研究

著者らは，圧縮抵抗型CFTブレースによる耐震補強を提案し，この補強架構の挙動について実験的な検討を行ってきた。本論では，実験挙動を模擬できる解析手法について検討を行った後，本補強法を建物に適用した際の補強効果について静的及び動的解析によって考察した。本論の解析は，実験で観測された補強架構の全体曲げ降伏挙動とブレースの座屈挙動を精度よく予測することが可能であった。その後，建物全体のモデルを作成し静的解析と動的解析を実施した。動的解析では，最大速度を0.5m/sに基準化した3つの観測波を使用した。これらの解析により，補強による耐力の上昇と最大応答変位の抑制効果を評価した。

Nonoperative Treatment of Thoracic and Lumbar Spine Fractures: A Prospective Randomized Study of Different Treatment Options

To evaluate and compare nonoperative treatment methods for traumatic thoracic and lumbar compression fractures and burst fractures. Prospective randomized controlled trial with long-term follow-up. Two general hospitals in the Netherlands. Patients with a traumatic thoracic or lumbar spine fracture, without neurologic damage, with less than 50% loss of height of the anterior column and less than 30% reduction of the spinal canal were included. Patients in the compression group were randomized to physical therapy and postural instructions, a brace for 6 weeks, or a Plaster of Paris cast for 6 or 12 weeks. Patients in the burst group received a brace or a Plaster of Paris cast, both for 12 weeks. Follow-up examinations included radiographs, Visual Analogue Scores for toleration of treatment and persistent pain, and an Oswestry Disability Index at long-term follow-up. There were 133 patients: 108 in the compression group and 25 in the burst group. For compression fractures, physical therapy and brace were considered the most tolerable. Brace therapy scored significantly better on the Visual Analogue Scores for residual pain and on the Oswestry Disability Index. None of the treatments had any significant effect on the residual deformity measurements. For burst fractures, no significant differences were found. Brace treatment with supplementary physical therapy is the treatment of choice for patients with compression fractures of the thoracic and lumbar spine. Furthermore, more than 20% of all patients had moderate or severe back pain at long-term follow-up.

Compressive orthotic bracing in the treatment of pectus carinatum: the use of radiographic markers to predict success

Purpose The treatment of pectus carinatum (PC) has classically been operative, though compressive orthotic braces have been used with good success in recent years. The purpose of this article is to evaluate the use of radiologic measurements in a successful bracing protocol. Methods Sixty-three patients with PC have been evaluated for an 8-year span. The average age is 13.3 ± 2.5. Follow-up is from 4 to 60 months, with a median of 24 months. Seventeen patients with mild defects elected observation alone. The remaining 46 patients began the bracing protocol. Baseline chest computed tomography (CT) was obtained, and custom-fitted orthotic braces were constructed for each patient. Radiographic markers were evaluated to include the Haller index, angle of sternal rotation, and asymmetry index. Patient surveys and chart review were used to identify compliance and success rates. Pretreatment CTs were retrospectively reviewed by bracing outcomes and radiographic measurements were compared. Ten patients received posttreatment CTs after successful bracing. Results Of 63 patients with PC, 17 patients (27%) with mild defects elected observation alone. The remaining 46 patients began the bracing protocol as described above. Of these, 10 are excluded from analysis, with 6 patients currently in the early treatment phase and 4 who have been lost to follow-up. Of the remaining 36 patients, 8 failed bracing because of noncompliance. Of the 28, 24 patients who completed treatment report either good or excellent results after bracing. Eight patients have required surgical intervention, 4 as a result of noncompliance and 4 who were compliant but failed bracing. In patients who were compliant, significant differences were seen on initial CT between those with successful outcomes and those who required surgical repair. Haller index (2.85 vs 2.05; P < .05), angle of sternal rotation (27.3 vs 14.8; P < .05), and asymmetry index (1.23 vs 1.06; P < .01) were all higher in the group who failed bracing. In those who successfully completed treatment, there was no significant difference in the Haller or asymmetry indices, but the average improvement in sternal rotation was 53.8%. Conclusion Compressive orthotic bracing is a successful method of treatment of pectus carinatum. The associated sternal rotation can be significantly improved with appropriate bracing that results in a subjective improvement in the deformity. Asymmetry of chest diameter related to concomitant excavatum-type deformity is less likely to respond to bracing attempts. In this way, initial chest CT can be of value in treatment planning.

Effect of the compressive brace in pectus carinatum

Patients with pectus carinatum complain of cosmetic problems because they stand out in spite of wearing clothes. Surgical treatment of pectus carinatum is resection of the deformed cartilage but a wide operative scar, postoperative pain and complications related with the operation can occur. Therefore we have performed compressive brace therapy as a non-operative treatment of pectus carinatum, and observed the effects and the efficiency of this treatment. From January 2001 to December 2007, 119 patients with pectus carinatum were treated with a compressive brace that they wore for 24h each day. Their degree of satisfaction was measured after 6 months wearing. This was evaluated with a score of 1-4. A score of 1 was assigned when the status was worse, 2 when it was same, 3 when partially improved, and 4 when a remarkable improvement was observed. Satisfaction was assessed subjectively by a parent if the patient was a child, and patients older than middle school age assessed the score themselves. The mean overall satisfaction score was 3.95+/-0.4. Recurrence of pectus carinatum after removal of the compressive brace occurred in 6 (5.0%) of the total 119 patients. Four of these six patients stopped wearing the compressive brace against our advice. These six patients were re-corrected by re-wearing the compressive brace within 3 months after they originally removed it. Complications were discomfort at initial wearing of the brace, which occurred in all patients, skin rash due to compression for 84 patients (70.6%) and skin discoloration due to excessive compression for 18 patients (15.1%). The skin rash and discoloration disappeared within a few months after removal of the brace. This study demonstrated that non-surgical treatment using a compressive brace in patients with pectus carinatum was effective, especially in children and teenagers. Non-surgical treatment using a compressive brace in patients with pectus carinatum would be helpful for those who dislike surgery because of their fear about general anesthesia and operative complications. But, long-term follow-up is necessary to evaluate the effectiveness of this compressive brace and the recurrence of the condition after its removal.

Use of a Novel Active Implant Enhanced Forearm Device in the Treatment of Lateral Tendinosis

Many treatment modalities have been proposed to manage this condition, and the vast majority of patients find at least some degree of relief from nonoperative interventions. The most commonly used methods include relative rest, nonsteroidal anti-inflammatory drugs (NSAIDs), and application of cold compresses. Other therapies currently in use or under investigation include acupuncture, acupressure, compressive braces, corticosteroid or botulinum toxin injections, occupational therapy, ultrasound, and laser or shock wave therapy. 5 Despite the multitude of interventions, there is a substantial persistence of symptomatology, and recurrence following resumption of normal activities is common. This study evaluates the use of a novel elbow brace that uses tubular counter-force elements, active implants, placed over the extensor digitorum tendinous insertion and energy dampening components placed over the lateral and medial epicondyles for the treatment of lateral tendinosis.

圧縮ブレースを用いる既存RC造ピロティ架構の耐震補強に関する実験的研究

A new seismic retrofitting technique using compressive bracings for existing R/C frames with soft story was experimentally tested. The bracing is composed of steel pipe in-filled high-strength mortar and its ends are designed to resist compressive bracing without tensile resistance. These make the conductivity of the seismic retrofit easier, the cost of works lower and the time of works shorter. Experimental testes were carried out to evaluate the reinforcing effect. Three strengthening specimens with the bracings and, for comparison, a non-strengthening specimen were constructed with a 1/5 dimensional scale factor. All specimens were tested under inelastic reversal loading. Test results indicated that the soft story was successfully seismic retrofitted, and that the lateral strength increased by approximately twice that of the non-strengthening frame. Test results also showed that the governing failure mechanism in the soft story was successfully shifted from a column sidesway mechanism to a total collapse mechanism.

Nonoperative Correction of Pectus Carinatum with Orthotic Bracing

This study sought to evaluate the efficacy of nonoperative compression in correcting pectus carinatum in children. Children presenting with pectus carinatum between August 1999 and January 2004 were prospectively enrolled in this study. The management protocol included custom compressive bracing, strengthening exercises, and frequent clinical follow-up. There were 30 children seen for evaluation. Their mean age was 13 years (range, 3-16 years) and there were 26 boys and 4 girls. Of the 30 original patients, 6 never returned to obtain the brace, leaving 24 patients in the study. Another 4 subjects were lost to follow-up. For the remaining 20 patients who have either completed treatment or continue in the study, the mean duration of bracing was 16 months, involving an average of 3 follow-up visits and 2 brace adjustments. Five of these patients had little or no improvement due to either too short a follow-up or noncompliance with the bracing. The other 15 patients (75%) had a significant to complete correction. There were no complications encountered during the study period. Compressive orthotic bracing is a safe and effective alternative to both invasive surgical correction and no treatment for pectus carinatum in children. Compliance is critical to the success of this management strategy.

Nonoperative management of pectus carinatum

Background Although surgery has been the mainstay of treatment of chondrogladiolar pectus carinatum (PC), several authors have advocated the benefits of nonoperative approaches to induce chest wall remodeling. Based on our initial success with compression bracing, we have integrated this modality into our treatment algorithm. Method We reviewed the charts of all patients treated for PC at our pediatric hospital between 1997 and 2004. Patients were managed with observation, operative repair, and orthotic bracing that provides continuous anteroposterior sternal compression. The brace was worn for 14 to 16 hours per day until linear growth was complete or for a minimum of 2 years. Results One hundred patients were diagnosed with PC. Fifty-seven patients had no treatment and were monitored. Twenty-nine patients were fitted with a brace. Of these 29 patients, 3 were noncompliant, resulting in a compliance rate of 90%. Of the remaining brace patients, all have had positive outcomes with no observed complications. Seventeen patients underwent surgical repair. Their outcomes were also positive with no major complications. Conclusion Our findings clearly demonstrate that compression bracing is a safe and effective treatment for children with chondrogladiolar PC. We currently offer this approach as a first-line treatment, reserving surgery for patients who are noncompliant and those who fail the nonoperative modality.

An assessment of seismic design practice of steel structures in the United States since the Northridge earthquake

AbstractThe 1994 Northridge earthquake served as a watershed event in the practice of seismic design of structural steel buildings. Damage to steel moment frame and concentrically braced buildings in this earthquake as well as similar types of damage observed in the 1995 Hyogoken‐Nambu earthquake illustrated the need to address design, construction, and quality shortcomings in design standards, methods of construction, and inspection practices. Research demonstrated that moment frame performance could be improved by shifting the location of the plastic hinge from the face of the column, use of higher notch‐tough welding electrodes, rigorous attention to proper fabrication and erection practices, and improved inspection practices emphasizing visual inspection. Changes to braced frame design provisions have emphasized development of full member strength in the connections, which has led to development of buckling restrained systems to better match tensile and compression brace capacities. This paper assesses the impact of post‐earthquake observations and some of the research initiatives that have changed the way in which structural steel seismic systems are designed. It attempts to identify the trends relative to selection of various steel seismic systems in response to perceived performance issues, limitations imposed by design standards and regulatory agencies, and economic factors. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Effect of positioning and bracing on passive position sense of shoulder joint

Objective: To examine the effects of positioning and sleeve type bracing on passive position sense of shoulder joints of healthy untrained subjects. Method: A cross over study was carried out...

木造軸組構法における柱脚接合部に入力される引張力に関する研究

This monograph relates tension of a column bases in adjustment between an experimental result and calculation by the standard or general design for conventional wooden structure. At first, 2-stories and 126 m^2 model house was given static load to examine the experimental measure and then 2 stories and 27 m^2 square houses was loaded in the same condition to investigate an effect of perpendicular walls to the load direction. Furthermore, some partial models of columns and sills were experimented to clarify the effect of rocking of column and confining of joint. After the experiments, the experimental measurement was revised with the effect of the rocking and confining, and compared with the standard calculation. As a conclusion, when the story deformation angle is 1/50rad. the rocking considerably affects the tension of column bases. The tension is not serious on every column base in the elastic limit. The required value of tension of corner columns seems to be unreasonable, but there is a noteworthy case that the tension more than the required value occurs to the column bases with compressive braces. The perpendicular walls shared with the corner columns seem to carry 1/3 to 1/2 of stress if it has the same specification as the walls in the same direction as the load.

Achieving a Stable Inelastic Seismic Response for Multi-Story Concentrically Braced Steel Frames

Recent seismic design provisions (CSA, 2001; AISC, 2002) for concentrically braced steel frames (CBFs) aim at dissipating seismic input energy through inelastic deformations in the bracing members. These deformations include tension yielding of the braces as well as plastic hinge rotation that develops upon buckling of the braces in compression and subsequent straightening of the braces when pulled in tension in the next loading cycle. Over the years, researchers have gained a good understanding of the hysteretic response of steel braces (Jain, Goel, and Hanson, 1980; Popov and Black, 1981; Astaneh-Asl and Goel, 1984; Astaneh-Asl, Goel, and Hanson, 1985) and detailing requirements such as maximum b/t and KL/r ratios are now prescribed in codes to achieve ductile brace response. Capacity design rules have also been introduced in codes to prevent premature failure of the brace connections and ensure that the response of the beams and columns will remain essentially elastic (Tremblay, 2001). Concentrically braced steel frames are particularly vulnerable to dynamic instability under seismic ground motions compared to other lateral load resisting systems due to the inherent poor hysteretic response of the diagonal bracing members and the tendency to develop story mechanisms in multi-story applications. The stability of CBFs responding in the nonlinear range to earthquake ground motions is a complex problem that depends on several parameters including the properties of the bracing members, the bracing configuration, the characteristics of the ground motions, the lateral resistance of the structure relative to the seismic demand and the amount of gravity loads supported by the structure. In multi-story frames, the potential for collapse by instability is also influenced by other parameters including the number of floors and the distribution of the lateral resistance over the building height. As of today, no simple method has been proposed for design purposes to adequately capture the combined effects of all these parameters.

The pseudo‐viscous frictional energy dissipator: a new device for mitigating seismic effects

AbstractViscous energy dissipators (EDORs) have good suppressing effects on acceleration or base shear and they do not add axial pressure to the column when peak moment in the column occurs at peak displacement. Pall frictional EDORs can dissipate energy even when the compression brace buckles due to a special frictional damping mechanism. Retaining the advantages of viscous and Pall EDORs and overcoming their disadvantages, a pseudo‐viscous frictional energy dissipator (PVEDOR) is developed. PVEDORs use the frictional damping mechanism of Pall EDORs, but the slip force of PVEDORs is made variable so that the slip force reduces with increasing displacement. Behaviour testing of PVEDORs shows that they possess the important hysteretic feature of viscous EDORs, i.e. the restoring force of PVEDORs are out‐of‐phase with displacement. Earthquake simulation tests of a 16‐storey frame structure incorporating PVEDORs and ordinary steel braces and bare frame are carried out. The test results show that PVEDORs have good vibration‐suppressing effects. An analytical hysteretic model of PVEDORs basically agrees with the behaviour testing results. Finally, the parameter influence of PVEDORs on suppressive effectiveness of structural vibration under earthquake conditions is studied. Numerical analyses show that PVEDORs have good control effects on both seismic displacement and acceleration, and that control effects of PVEDORs on base shear are much better than Coulomb‐type frictional EDORs or metallic EDORs. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Stability of pretwisted beams in cross bracings

New systems of pretwisted bars are suggested, and their stability under a conservative load is investigated. In this paper, closed‐form relationships are obtained for the direct evaluation of critical loads of pretwisted cross bracings with different end connections and an arbitrary ratio of the dimensionless parameters of tension and compression elements. The equation for the critical loads is derived for tension and compression braces with different section properties, lengths, and axial loading. It is found that the critical load of a twisted brace is higher than that of a nontwisted brace. Parametric solutions are graphically displayed to clarify the distinct behavior, including the boundary separating symmetric and antisymmetric modes of buckling.

Stiffening Requirements for Unbonded Braces Encased in Concrete Panels

This paper addresses the design and behavior of a composite brace system comprised of unbonded steel flat-bar brace embedded in a precast reinforced concrete panel. Debonding material is painted onto the steel flat-bar brace to remove the bond stress between the steel flat-bar brace and the precast concrete panel, so that axial load is applied only on the steel flat-bar brace. The precast concrete panel of a stiffening member is designed to prevent the steel flat-bar brace from buckling in order to effectively mobilize the compressive brace together with the tensile brace during seismic loading. The stiffening requirements to restrain the buckling of the steel flat-bar brace are derived from equilibrium considerations, and are verified by tests. Two types of tests were performed: (1) fundamental buckling tests; and (2) tests of frame with the stiffened brace subjected to the earthquake type of loading. By using the stiffened brace as a hysteretic damper, a designer does not have to consider the complicated postbuckling behavior of steel braces, and can easily control the horizontal stiffness, strength, and energy absorption capacity of steel buildings.

Ultimate Capacity of Doubler Plate–Reinforced Tubular Joints

To ensure structural integrity after modification and/or retrofitting, the behavior of strengthened tubular joints needs to be understood. The finite-element method is a useful tool for studying the problem. However, this numerical technique has to be verified by experimental results before being used extensively. In this paper, the ultimate capacity of doubler plate–reinforced tubular joints is studied. To establish a reference point, a doubler plate–reinforced tubular T-joint was fabricated, instrumented, and tested to failure under axial compression brace loading. The structural behaviors were observed and analyzed. It was found that the ultimate capacity was greatly improved by the inclusion of the doubler plate. The experimental load-displacement curves were compared with the finite-element predictions and good agreement was obtained. The finite-element techniques were then verified and could be used to study the ultimate capacity. A behavioral study was then conducted by applying various types of brace loading and varying different geometric parameters, one at a time.

Biomechanics and Functional Anatomy of Hollow Stemmed Sphenopsids: III. Equisetum hyemale

Abstract:As in Equisetum giganteum, the hollow stem of Equisetum hyemale owes the mechanical stability of the internodes to an outer ring of strengthening tissue (hypodermal sterome) which provides stiffness and strength in the longitudinal direction. In contrast to hollow‐stemmed grasses, the hypodermal sterome consists of living cells. The compound inner tissue of the overwintering aerial stem of Equisetum hyemale includes a continuous inner and outer endodermis layer of vital thick‐walled cells that have slightly lignified Casparian thickenings. The two endodermis layers provide an inner tension and compression bracing which lend resistance to local buckling. The stress‐strain relation in longitudinal tension is biphasic with remarkably high critical strains especially in the upper parts of the stem. Scraping off part of the epidermis with the built‐in silicate does not change this behaviour, except in the initial steep part of the curve where the Young's modulus is reduced by 20%. No contribution of the endodermis and the parenchyma could be detected in tension tests of longitudinally‐oriented strips. Relaxation experiments reveal viscoelastic behaviour. As with the biphasic stress‐strain relation and the critical strains, the viscoelastic properties have largely to be ascribed to the hypodermal sterome.

Aluminium shear-links for enhanced seismic resistance

SUMMARY An aluminium beam shear-link is developed for earthquake-resistant structures. The aluminium beam is designed to yield in shear mode to limit the maximum lateral force which is transmitted to primary structural members and to provide significant energy dissipation potential. Aluminium was chosen because of its low yield strength, which enables the use of thicker webs, reducing the problems of web buckling. Cyclic load tests on medium scale (1 : 4) models were conducted to study the hysteretic behaviour and energy dissipation potential of shear-links made of two alloys of aluminium (3003-O and 6061-O). The links were also tested at faster rates (cycling frequencies of 5, 10 and 17 Hz) to determine the e⁄ect of strain rate. The links exhibited very ductile shear yielding and excellent energy dissipation capacity. Unpinched and full hysteresis loops were observed until 10 per cent shear strain, and a relatively small influence of strain rates was observed on the link’s performance. Simple design equations are developed to proportion these shear-links, using data from the cyclic load tests. In chevron-type braced systems, the shear-link is sandwiched between the tops of diagonal braces and a girder from the floor above, resulting in yielding at a lateral force less than that required to buckle the compression brace. A Shear-Link Braced Frame (SLBF) system was designed and its seismic performance was compared to that of an Ordinary Concentric Braced Frame (OCBF) with chevron braces. The SLBF system demonstrated more uniform distribution of storey drifts, reduced base shear, and a larger energy dissipation capacity per unit drift. ( 1998 John Wiley & Sons, Ltd.

Use of steel bracing in reinforced concrete frames

In this paper the use of steel bracing in concrete-framed structures is investigated. The investigation is carried out through a series of tests conducted on a number of model frames. The object of the tests was to determine the degree of effectiveness of different diagonal bracing arrangements to increase the in-plane shear strength of the concrete frame and to observe the relative behaviour of tension and compression braces. The important question of the proper connections between the steel braces and the concrete frame is also considered. The test results indicate a considerable increase in the in-plane strength of the frame due to steel bracing. As an overall conclusion it is noted that, with proper connection between the brace and the frame, the steel bracing could be a viable alternative or supplement to shear walls in concrete framed buildings in seismic areas.

THE EFFECT OF CRACKS AT ONE SADDLE ON THE STATIC STRENGTH OF DIE CAST TIN-LEAD ALLOY T-, Y- AND YT-TUBULAR JOINTS.

Keywords NOTTINGHAM UNIVERSITY STRUCTURES, OFFSHORE, CRACKS, JOINTS, SADDLES, DIES, CAST, TIN, LEAD, ALLOYS, TUBULAR, T JOINTS, Y JOINTS, YT JOINTS, METAL, MODELS, METHODS, STATIC, STRENGTH, SHIMS, MOULDS, TESTS, AXIAL, COMPRESSION, BRACES, BENDING, OUT OF PLANE, LOADING, LOADS, COMPRESSIVE, REDUCTION, TENSILE, CHORDS, DEFORMATION... Show All