• Title/Summary/Keyword: double plates

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Strengthening of the panel zone in steel moment-resisting frames

  • Abedini, Masoud;Raman, Sudharshan N.;Mutalib, Azrul A.;Akhlaghi, Ebrahim
    • Advances in Computational Design
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    • v.4 no.4
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    • pp.327-342
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    • 2019
  • Rehabilitation and retrofitting of structures designed in accordance to standard design codes is an essential practice in structural engineering and design. For steel structures, one of the challenges is to strengthen the panel zone as well as its analysis in moment-resisting frames. In this research, investigations were undertaken to analyze the influence of the panel zone in the response of structural frames through a computational approach using ETABS software. Moment-resisting frames of six stories were studied in supposition of real panel zone, different values of rigid zone factor, different thickness of double plates, and both double plates and rigid zone factor together. The frames were analyzed, designed and validated in accordance to Iranian steel building code. The results of drift values for six stories building models were plotted. After verifying and comparing the results, the findings showed that the rigidity lead to reduction in drifts of frames and also as a result, lower rigidity will be used for high rise building and higher rigidity will be used for low rise building. In frames with story drifts more than the permitted rate, where the frames are considered as the weaker panel zone area, the story drifts can be limited by strengthening the panel zone with double plates. It should be noted that higher thickness of double plates and higher rigidity of panel zone will result in enhancement of the non-linear deformation rates in beam elements. The resulting deformations of the panel zone due to this modification can have significant influence on the elastic and inelastic behavior of the frames.

A study on the sound transmission through double plates installed inside an impedance tube (임피던스 튜브 내에 설치된 이중 평판의 음파투과연구)

  • Kim, Hyun-Sil;Kim, Bong-Ki;Kim, Sang-Ryul;Seo, Yun-Ho;Ma, Pyung-Sik
    • The Journal of the Acoustical Society of Korea
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    • v.35 no.4
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    • pp.253-260
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    • 2016
  • In this paper, derivation of the STL (Sound Transmission Loss) of the double plates installed in an impedance tube is discussed using an analytic method, where an air cavity exists between the plates. Vibration of the plates and sound pressure field inside the tube are expressed in terms of infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results, and locations of peaks and dips are investigated. It is determined that the peak frequencies of the double plates coincide with those of each single plate. When the two plates are identical, the STL of the double plates as well as that of the single plate become zero at the natural frequencies of the single plate. The location and amplitude of the dips are investigated using an approximation solution when the cavity depth is very small.

Improved Strain Influence Diagram and Settlement Estimation for Rectangular and Multiple Footings in Sand (수정변형률 영향계수에 근거한 직사각형 및 복합 얕은기초 침하량 산정법)

  • Park, Dong-Gyu;Lee, Jun-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.633-640
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    • 2005
  • Most existing methods for the footing settlement estimation are for either isolated or strip footings. No sufficient details are available for settlement calculation of footings with different shapes and multiple footing conditions, which are commonly adopted in actual construction projects. In this paper, estimation of footing settlements for various footing conditions of different shapes and multiple conditions is investigated based on Schmertmann's method with focus on values of the strain influence factor $I_z$. In order to examine the effect of multiple footing conditions, field plate load tests are performed in sands using single and double plates. 3D non-linear finite element analyses are also performed for various footing conditions with different footing shape and distance ratios. Results obtained in this study indicate that there are two significant components in the strain influence diagram that need to be taken into account for settlement estimation of rectangular and multiple footings: depth of $I_{zp}$ and depth of strain influence zone. Based on results from experimental and 3D non-linear finite element analyses, improved strain influence diagrams available for various footing conditions are proposed.

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Clinical Results of Supracondylar Dome Osteotomy for Cubitus Varus and Valgus Deformities in Adults

  • Gwark, Ji-Yong;Im, Jin-Hyung;Park, Hyung Bin
    • Clinics in Shoulder and Elbow
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    • v.19 no.4
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    • pp.229-236
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    • 2016
  • Background: Cubitus varus and cubitus valgus deformities are common complications of distal humeral fractures in children. We evaluated the usefulness of supracondylar dome osteotomy as a treatment option for adults with cubitus varus or valgus deformity developed during childhood. Methods: Ten patients who had received supracondylar dome osteotomy and stabilization with plates to treat cubitus varus or valgus deformity between July 2006 and August 2013 were included in this study. Their mean age at the time of surgery was $36.50{\pm}10.22years$. The mean follow-up duration was $54.80{\pm}32.50months$. We evaluated humerus-elbow-wrist angles (HEWA), improvements in the lateral prominence index (LPI) or medial prominence index (MPI), Mayo elbow performance scores (MEPS), and overall results in accordance with the Banerjee criteria. Results: For the six patients with cubitus varus, the mean postoperative HEWA, mean correction angle, and mean improvement in LPI were $9.72^{\circ}{\pm}3.95^{\circ}$, $27.67^{\circ}{\pm}10.75^{\circ}$, and $6.92%{\pm}3.40%$, respectively. For the four patients with cubitus valgus, the mean postoperative HEWA, mean correction angle, and mean improvement in MPI were $14.73^{\circ}{\pm}2.97^{\circ}$, $11.55^{\circ}{\pm}3.26^{\circ}$, and $11.33%{\pm}6.39%$, respectively. There was no significant difference between postoperative and preoperative mean MEPS. The subjective ulnar nerve symptoms were alleviated in all patients. The overall results were excellent in six and good in four patients. Conclusions: This study suggests that supracondylar dome osteotomy with secure fixation using double plates may be useful in correcting cubitus varus or cubitus valgus deformity, yielding good functional outcomes in adults.

The Results of Surgical Treatment of Comminuted Fractures of Distal humerus (원위 상완골 분쇄 골절의 수술적 치료 결과)

  • Cho Nam-Su;Park Sung-Woo;Jung Ki-Yoen;Rhee Yong-Girl
    • Clinics in Shoulder and Elbow
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    • v.8 no.2
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    • pp.97-104
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    • 2005
  • Purpose: To report the results of surgical treatment of comminuted fractures of distal humerus and to identify factors that affect the results. Materials and Methods: Thirty-two patients who were treated with open reduction and internal fixation for comminuted fracture of distal humerus were enrolled. According to the AO classification, A2.3 was 1 case, A3.2, 2 cases, A3.3, 8 cases, B1.3, 1 case, B2.3, 1 case, C2.2, 5 cases, C2.3, 4 cases, C3.2, 3 cases and C3.3, 7 cases. As fixation technique, 17 cases were fixed by double plates, 4 cases by only K-wires, 4 cases by only screws, 3 cases by K-wires and screws and 4 cases by one plate and screws. The mean age at the time of the operation was 49 years(range, $19{\sim}77$ years). The mean follow-up period was 16 months(range, $8{\sim}51$ months). Results: At the last follow-up, the mean maximum flexion was $116.4^{\circ}\;(range,\;85{\sim}140^{\circ})$ and the mean loss of terminal extension was $11.8^{\circ}\;(range,\;0{\sim}40^{\circ})$. The average Mayo elbow performance score was $91.4^{\circ}\;(range,\;55{\sim}100^{\circ})$. Overall 29 cases(91%) showed good to excellent results. The mean range of motion of extraarticular and intraarticular fracture group was $105.5^{\circ}\;(range,\;65{\sim}140^{\circ})$ and $104^{\circ}\;(range,\;55{\sim}140^{\circ})$, respectively. The average elbow score of both groups was$93^{\circ}\;(range,\;70{\sim}100^{\circ})$ and $90.7^{\circ}\;(range,\;55{\sim}100^{\circ})$. Over 90% showed more than good results. 30 cases(94%) showed complete bony union but two cases, nonunion. One case of the nonunion cases underwent replating with bone graft as revision surgery and total elbow arthroplasty was performed in the other case. At the last follow-up, 27 patients(84.4%) showed subjective satisfaction. Conclusion: Open reduction and internal fixation with appropriate surgical technique for comminuted fractures of distal humerus showed good results, which were not affected by age at the time of operation, fixation methods and anterior transposition of the ulnar nerve. Transolecranon approach may be considered as good choice for intraarticular comminuted fractures of distal humerus.