有限元对钢折板-混凝土组合桥面板的性能研究

通过采用有限元程序对这种新型结构进行力学性能分析和研究,并将其与传统钢筋混凝土桥面板、未带波形的普通钢板-混凝土组合桥面板进行承载力、力学性能和刚度等进行综合对比。结果表明,钢折板-混凝土组合桥综合性能最佳,面板受力最合理、承载力最高、刚度最大、自身质量最轻,具备其他桥面板无可比拟的优势。

波形钢―混凝土组合桥面板受力性能研究

为研究新型桥面板结构波形钢-混凝土组合桥面板的受力性能,以安徽省淮南孔李淮河大桥的桥面板为研究对象,应用有限元软件ABAQUS建模,采用子模型法,计入混凝土、波形板及钢筋的材料非线性,考虑混凝土与波形板之间的接触非线性,比较了波形钢-混凝土组合桥面板和钢筋混凝土桥面板的承载能力和刚度。研究结果表明:波形钢折板可显著提高桥面板的抗弯承载能力及刚度;波形板及混凝土底面应变沿桥梁横向分布波动较大;波形板与混凝土之间相对滑移量较小,2种材料协同工作性能较好,然而波形板与混凝土的法向接触行为并不均匀。

上海世博会民企联合馆设计及其新技术应用

介绍2010上海世博会民企联合的建筑设计及其新技术的应用。重点介绍建筑中首次运用的镭射智能膜技术、钢折板应用技术和双LED屏系统。

H型钢梁-H型钢柱偏心节点局部屈服荷载承载力的力学行为研究

针对槽形钢折板补强H型钢梁-H型钢柱的偏心节点,研究了节点局部屈服荷载承载力的力学行为。通过建立5种可能形成的塑性屈服破坏模型,利用屈服线理论,推导出H型钢梁-H型钢柱偏心节点的局部屈服荷载承载力计算公式。取包含梁受拉翼缘在内的节点构件(1/4模型)作为试件,进行了6组拉伸加载试验,验证偏心节点的弹塑性响应。通过对应变分布和翼缘平面外残余变形响应的分析来验证塑性屈服破坏模型的准确性。

H型钢梁-H型钢柱偏心节点的节点域力学性能研究

提出利用槽形钢折板补强H型钢梁-H型钢柱的偏心节点,并研究了该偏心节点的力学性能。提出偏心节点的节点域承载力计算方法,分析中考虑了由于梁偏心引起的附加扭矩的影响。同时进行了T字形梁柱构件的循环荷载试验,验证偏心节点的滞回性能。试验结果表明,节点具有良好的延性和耗能性能,节点域承载力计算公式具有良好的精度。以十字形梁柱构件为模型,进行非线性有限元数值分析,考察槽形钢折板的厚度对偏心节点域变形和承载力的影响。

Minimally invasive plate internal fixation for calcaneal fractures

Objective： To assess the clinical efficacy of minimally invasive plate internal fixation for the treatment of calcaneal fractures. Methods： Manual reduction, rectification of deformity, and cold compress with traditional Chinese medicine were used preoperatively to relieve swelling and pain. A small incision was made to expose the articular facet and to perform anatomic reduction and plate fixation. Self-made traditional Chinese pharmaceutics were applied postoperatively on the surface of the wound to accelerate bony union. Results： All the 40 patients were followed up for at least 1 year postoperatively. According to the Maryland scoring system, the excellent and good rate was 87.5%. Conclusion： Minimally invasive plate internal fixation has the advantages of relatively mild injury, reliable fixation, good recovery, and rare complications in the treatment of intraarticular fractures.

Distal tibial fracture： An ideal indication for external fixation using locking plate

Objective： To evaluate the feasibility and efficiency of one-stage external fixation by using locking plate in distal tibial fractures. Methods： In this non-control prospective study, 28 patients with distal tibial fractures were included and underwent one-stage external fixation by using locking plate. There were 21 males and 7 females, with a mean age of 43 years （19-63）. According to AO/OTA fracture classification, there were 9 cases of Type A1, 9 of Type A2, 10 of Type A3 fractures. There were 21 close and 7 open fractures. The locking plate was placed on the anteromedial aspect of the tibia with 4-5 bicortical screws inserted in both distal metaphysis and diaphysis. The radiographic and clinic results were evaluated. Results： All patients were followed up for the average of 16 months （ranging from 12 to 21 months）. The average surgery duration was 38 （25-60） minutes. The mean time to fracture healing were 14.6 ± 2.67, 17.5 ± 3.66, and 18.4±3.37 （p 〈 0.05） weeks in type A1, A2, and A3 fractures respectively. By the end of the follow-ups, the mean AOFAS score were 96.11 ± 2.32, 92.67 ± 1.80 and 92.00± 2.06 （p 〉 0.05） in type A1, A2, and A3 fractures respectively. None of nonunion, deep infection, or breakage of screw or plate were observed. Conclusions： Distal tibial fracture was the ideal indication for external fixation using locking plate. The external plating is characterized by ease of performance, less invasive, fewer soft tissue impingement, improved cosmesis, and convenient for removal.

Surgical treatment of proximal humerus fractures using PHILOS plate

Objective：To evaluate functional outcome and complications of open reduction and internal fixation with proximal humeral internal locking system （PHILOS） plate for proximal humerus fractures.Methods：We reviewed 51 patients who underwent open reduction and internal fixation with PHILOS plate between the years 2007 to 2012.There were 35 men and 16 women with a mean age of 38 years （range 24-68）.There were 41 patients in the age group of ＜60 years and 10 patients in the age group of ＞60 years.According to Neer classification system,8,15 and 23 patients had 2-part,3-part,and 4-part fractures,respectively and 5 patients had 4-part fracture dislocation.All surgeries were carried out at our tertiary care trauma centre.Functional evaluation of the shoulder at final follow-up was done using Constant-Murley score.Results：The mean follow-up period was 30 months （range 12-44 months）.Two patients were lost to followup.Of the remaining 49 patients,all fractures were united clinically and radiologically.The mean time for radiological union was 12 weeks （range 8-20 weeks）.At the final follow-up the mean Constant-Murley score was 79 （range 50-100）.The results were excellent in 25 patients,good in 13 patients,fair in 6 patients and poor in 5 patients.During the follow-up,four cases of varus malunion,one case of subacromial impingement,one case of deep infection,one case of intraarticular screw penetration and one case of failure of fixation were noted.No cases of avascular necrosis,hardware failure,locking screw loosening or nonunion were noted.Conclusion：PHILOS provides stable fixation in proximal humerus fractures.To prevent potential complications like avascular necrosis,meticulous surgical dissection to preserve vascularity of humeral head is necessary.

Buttress plating for a rare case of comminuted medial condylar Hoffa fracture associated with patellar fracture

Hoffa fracture is an uncommon injury. In the literature, lateral condylar Hoffa fracture is mentioned as a more common injury pattern than medial condylar Hoffa fracture. The mechanism of injury and method of treatment is not very well described in the literature. We are present- ing a rare case of comrninuted medial condylar Hoffa frac- ture with ipsilateral patellar fracture. The mechanism of in-jury has not been described in the literature. Lag screw fixation, which is the most acceptable method of treatment, is not possible due to comminution. We explain the pos- sible mechanism of injury and fix the fracture with L-but- tress plate.

Indirect reduction technique using a distraction support in minimally invasive percutaneous plate osteosynthesis of tibial shaft fractures

Purpose： To describe an indirect reduction technique during minimally invasive percutaneous plate osteosynthesis （MIPPO） of tibial shaft fractures with the use of a distraction support. Methods： Between March 2011 and October 2014, 52 patients with a mean age of 48 years （16-72 years） sustaining tibial shaft fractures were included. All the patients underwent MIPPO for the fractures using a distraction support prior to insertion of the plate. Fracture angular deformity was assessed by goniometer measurement on preoperative and postoperative images. Results： Preoperative radiographs revealed a mean of 7.6°（1.2°-28°） angulation in coronal plane and a mean of 6.8°（0.5°-19°） angulation in sagittal plane. Postoperative anteroposterior and lateral radio graphs showed a mean of 0.8°（0°-4.0°） and 0.6°00-3.6°） of varusvalgus and apex anterior/posterior angulation, respectively. No intraoperative or postoperative complications were noted. Conclusions： This study suggests that the distraction support during MIPPO of tibial shaft fractures is an effective and safe method with no associated complications.

Role of locking plates in treatment of difficult ununited fractures： a clinical study

Objective： To present our experience in treatment of difficult ununited long bone fractures with locking plate. Methods： Retrospective evaluation of locking plate fixation in 10 difficult nonunions of long bone fractures was done. Fixation was done with locking plate for femoral shaft fracture （3 patients）, supracondylar fracture of femur （gap nonunion）, fracture of clavicle, fracture of both forearm bones （radius and ulna） fracture of ulna, fracture of shaft of humerus, fracture of tibial diaphysis and supracondylar frac- ture of humerus （one patient each）. Five fractures had more than one previous failed internal fixation. One patient had infected nonunion which was managed by debridement with cast immobilization followed by fixation with locking plate at six weeks. Seven fractures were atrophic, two were oligotrophic, and one was hypertrophic. Fibular autograft was used in 2 cases and iliac crest cancellous bone graft used in all the patients. Results： Minimum follow-up was 6 months （range, 6 months to 2.5 years）. Average time for union was 3.4 months （range 2.5 to 6 months）. None of the patients had plate- related complications or postoperative wound infections. Conclusion： Along with achieving stability with locking compression plate, meticulous soft tissue dissection, acceptable reduction, good fixation technique and bone grafting can help achieve union in difficult nonunion cases. Though locking plate does not by itself ensure bony union, we have found it to be another useful addition to our armamentarium for treating difficult fracture nonunions.

Internal fixation with headless compression screws and back buttress plate for treatment of old Hoffa fracture

Objective： To analyze the early clinical and radiographic outcomes of Hoffa fractures treated by a standard protocol of open reduction and internal fixation using headless compression screws combined with back buttress plate in a consecutive series of 8 Chinese patients. Methods： Open reduction and internal fixation was performed on all patients. The fractures were anatomical- ly reduced and held temporarily by K-wire. If the ends of fractures were atrophic, autologous bone graft from the ipsilateral iliac crest was packed between the ends. Then the fracture fragments were fixed with AO 6.5 mm headless compression cannulated screws. At least two screws were used to provide rotational stability. One pre-contoured reconstruction plate was placed on the nonarticular surface posteromedially or posterolaterally as back buttress plate. Results： All the patients were followed up for at least 12 months （range 12-25 months）. All fractures achieved anatomical reduction and healed clinically and radiographically. At recent follow-up, the mean flexion degree was 120.6° （range 110°-135°） and the mean extension degree was 2.5° （range 0°-5°）. The average visual analogue scale score was 1.6 points （range 0-3）. Six patients were assessed as excellent and 2 as good according to the hospital for special surgery knee score system. There were no superficial or deep infections, or hardware breakages. No patient had giving way or locking of the knee, though some had intermittent pain and swelling after strenuous exercise. Injury mechanism had significant influence on the functional outcome （P=0.046）. Conclusion： Headless compression screws combined with back buttress plate and/or autologous bone grafting to treat old Hoffa fracture is one of effective measures. It would be conducive to not only fracture healing but also early exercise and functional recovery.

Sanders II-III calcaneal fractures fixed with locking plate in elderly patients

Purpose： To evaluate the clinical outcomes of locking calcaneal plate in treating calcaneal fracture （Sanders II-IIl） in elderly patients. Methods： From October 2012 to December 2013, 23 elderly patients suffering from calcaneal fracture （Sanders Ⅱ-Ⅲ） were treated and followed up. There were 15 males and 8 females with the mean age of 68.5 years （range： 65-79 years）. According to Sander＇s classification, 16 cases （16 feet） were type II fractures and 7 cases （7 feet） were type llI fractures. Anteroposterior, lateral and axial views of X-ray were taken to detect the calcaneum. CT scan was done to assess the amount of comminution and articular depression. Radiological assessment was performed using Bohler＇s angle and Gissane＇s angle. Functional outcome was assessed using the Maryland foot score. Results： All the patients were followed up for 13.7 months on average （10-20 months）. The mean time of bone union was 3.2 months （3-4 months）. The mean time of complete weight bearing was 3.2 months （3.1-4.0 months）. The soft tissue necrosis was found in 1 case. The mean Bohler＇s angle and Gissane＇s angle were 25.31° and 117.5° respectively. The overall excellent to good rate was 82.6%. Conclusion： Open reduction and internal fixation with locking calcaneal plate can obtain good functional outcome for Sanders II-III calcaneal fractures in elderly patients.

Interface contact profiles of a novel locking plate and its effect on fracture healing in goat

Objective： To evaluate the interface characteristics of the new-designed locking plate （LP） and limited contact-dynamic compression plate （LC-DCP） and compare the fracture healing between LP and LC-DCP in a goat tibia fracture model. Methods： Eight-hole LP and LC-DCP were applied to fix fresh goat tibiae in a reproducible manner. The average pressure, force and interface contact area were calculated using Fuji prescale pressure sensitive film interposed among the plate and the bone and image analysis system, Eighthole LP and LC-DCP were applied to each tibia in a goat tibia fracture model. The fracture healing was evaluated by X-ray photography at postoperative 8 weeks. The goats were sacrificed at postoperative 12 weeks. Three-point bending test was conducted in the tibiae. Results： The interface contact of LP system was smaller than that ofLC-DCP （P〈0.05）, while interface contact force of LP system was higher than that of LC-DCP （P〈0.05）. Radiographs revealed that the fracture line disappeared in the LP group, while the fracture line was visible in DCP group at postoperative 8 weeks. At postoperative 12 weeks, the bending strength and bending load of fractured tibia were higher in LP group than in DCP group, respectively.