目的通过研究步态轮廓评分(GPS)和运动分析剖面图(MAP)来量化青年慢性非特异性腰痛(chronic nonspecific low back pain,CNLBP)患者和健康青年人步态周期中的运动学变化。方法采用3D光学运动捕捉系统(Qualisys,Gothenburg,Sweden)采集CN...目的通过研究步态轮廓评分(GPS)和运动分析剖面图(MAP)来量化青年慢性非特异性腰痛(chronic nonspecific low back pain,CNLBP)患者和健康青年人步态周期中的运动学变化。方法采用3D光学运动捕捉系统(Qualisys,Gothenburg,Sweden)采集CNLBP组和健康组受试者各11例的步态运动学数据,将其导入索尔福德大学Richard Baker教授编写的Excel文件并计算出GPS和MAP分数,并进行统计学分析。结果右膝关节膝关节屈曲和伸展GVS值CNLBP组为(5.66±1.83)°,健康组为(3.64±1.13)°,组间比较,差异有统计学意义(P<0.01),2组受试者其余各项GVS变量和GPS组间比较,差异均无统计学意义(P>0.05)。结论青年CNLBP患者存在步态异常,GPS和MAP在青年CNLBP患者的步态评估中具有一定的适用性。展开更多
In steel-concrete composite twin-girder decks, wide concrete slab would undergo significant shear lag warping effect, including positive and negative. Some researchers have investigated the positive shear lag of compo...In steel-concrete composite twin-girder decks, wide concrete slab would undergo significant shear lag warping effect, including positive and negative. Some researchers have investigated the positive shear lag of composite decks by means of one-dimensional line model, while the studies on the negative shear lag have not yet been reported until now. In this study, a new one-dimensional analytical model of composite twin-girder decks is first proposed based on the model proposed by Dezi et al. Besides slab shear lag effect and partial connection at slab-girder interface which have been included in the model of Dezi et al., the particularity of the proposed model relies on its ability to account for variation characteristic of cross-section. Verification of the analytical model is later conducted through comparison of results from the analytical analysis and elaborate FE analysis for a simply supported composite deck with increasing depth and a two-span continuous one with decreasing depth. Finally, three kinds of structural forms of composite twin-girder decks, including cantilever, simply supported and continuous decks, are selected to carry out the analysis of positive and negative shear lag behaviors by means of the analytical model. The influences of cross-sectional variation characteristic and load type on positive and negative shear lag behaviors are mainly investigated. Additionally, a new definition on effective width for considering simultaneously positive and negative shear lag behaviors is proposed. The results from the proposed analytical model and EC4 specification are compared to provide suggestions for designers and checkers. In this study, the proposed analytical model can provide a powerful numerical tool for researchers to conduct the further investigation, and the analysis on shear lag and effective width can assist in design analysis of composite twin-girder decks.展开更多
基金supported by the Fundamental Research Fund for the Central Universities(Grant No.2015JBM069)the Research Fund for Talented Scholars of Beijing Jiaotong University(Grant No.2016RC026)
文摘In steel-concrete composite twin-girder decks, wide concrete slab would undergo significant shear lag warping effect, including positive and negative. Some researchers have investigated the positive shear lag of composite decks by means of one-dimensional line model, while the studies on the negative shear lag have not yet been reported until now. In this study, a new one-dimensional analytical model of composite twin-girder decks is first proposed based on the model proposed by Dezi et al. Besides slab shear lag effect and partial connection at slab-girder interface which have been included in the model of Dezi et al., the particularity of the proposed model relies on its ability to account for variation characteristic of cross-section. Verification of the analytical model is later conducted through comparison of results from the analytical analysis and elaborate FE analysis for a simply supported composite deck with increasing depth and a two-span continuous one with decreasing depth. Finally, three kinds of structural forms of composite twin-girder decks, including cantilever, simply supported and continuous decks, are selected to carry out the analysis of positive and negative shear lag behaviors by means of the analytical model. The influences of cross-sectional variation characteristic and load type on positive and negative shear lag behaviors are mainly investigated. Additionally, a new definition on effective width for considering simultaneously positive and negative shear lag behaviors is proposed. The results from the proposed analytical model and EC4 specification are compared to provide suggestions for designers and checkers. In this study, the proposed analytical model can provide a powerful numerical tool for researchers to conduct the further investigation, and the analysis on shear lag and effective width can assist in design analysis of composite twin-girder decks.
