Mechanism of improving ductility of high strength concrete T-section beam confined by CFRP sheet subjected to flexural loading

For the purpose of inventing a new seismic retrofitting method for the reinforced high strength concrete （HSC） T-section beam using carbon fiber reinforced polymer （CFRP） sheet, three series, a total of twelve T-section beams with nine specimens confined by CFRP sheet in the plastic zone and three control beams were conducted up to failure under four-point bending test. The effectiveness of confining CFRP sheet on improving the flexural ductility of tmstrengthened T-section beams was studied. The parameters such as the width and the thickness of CFRP sheet and the type of T-section were analyzed. The experimental results show that ductility and rotation capacity of plastic hinge can be improved by the confinement of CFRP sheet, and the ductility indices increase with the increment of width and thickness of CFRP sheet. A plastic rotation model considering the width of CFRP sheet and the effect of flange of T-section beam is proposed on the basis of the model of BAKER, and the test results show a good agreement with the perdicted results. The relevant construction suggestions for seismic retrofitting design of beam-slabs system in cast-in-place framework structure are presented.

Numerical and experimental study on seismic behavior of concrete-filled T-section steel tubular columns and steel beam planar frames

The seismic behavior of planar frames with concrete-filled T-section columns to steel beam was experimentally and numerically studied. A finite element analysis （FEA） model was developed to investigate the engineering properties of the planar frames. Two 1：2.5 reduced-scale specimens of T-section concrete-filled steel tubular column and steel beam of single-story and single-bay plane frames were designed and fabricated based on the design principles of strong-column, weak-beam and stronger-joint. One three-dimensional entity model of the investigated frame structure was built using a large-scale nonlinear finite-element analysis software ABAQUS. Experimental results show that the axial compression ratio has no effect on the failure mode of the structure, while with the increase of axial compression ratio and the dissipated energy ability increasing, the structural ductility decreased. The results from both experiments and simulations agree with each other, which verifies the validity and accuracy of the developed finite element model. Furthermore, the developed finite element model helps to reflect the detailed stress status of the investigated frame at different time and different positions.

Repairing of RC T-Section Beams with Opening by CFRP for Cracks and Ultimate Torque

The repair of reinforced concrete(RC)beams with carbon fiber reinforced polymers(CFRP)is experimentally investigated in this study.The four T-section reinforced reactive powder concrete beams with many locations of circular opening were repaired by CFRP and investigated under pure torsion.The repairing beams were tested to obtain the effect of the amount of CFRP laminate on beams cracking and ultimate torque behavior,angle of twist and failure modes.The results obtained from the adopted repairing technique showed a significant effect of external high strength CFRP laminates on effectively restore of section solid of 85%of crack torsional strength effectively restored.In addition,the results show that effectively restoring of section opening by 82%-80%of crack torsional strength,and the adopted repairing technique gives a good strength to the beams.

Effect of Cold Plasma on Binding Strength of Bamboo

[Objective] The paper was to study the effect of cold plasma on binding strength of bamboo. [Method] The bamboos were treated by 4 kinds of cold plasma nitrogen, oxygen, ammonia and argon, and the changes of contact angle and binding strength of bamboos before and after treatment were tested. [Result] Oxygen cold plasma treatment could increase binding strength of bamboo by 25%-30%. The cold plasma treatment was very fast and effective, but the changes of contact angle was not great in this experiment. [Conclusion] Cold plasma treatment could increase the binding strength of bamboo.

102例干眼症的临床特征分析

目的:分析干眼症的主要临床特征,探讨干眼症的临床诊断策略。方法:对疑诊为干眼的156例眼科门诊患者进行干眼症状问卷调查,并进行常规裂隙灯检查、泪膜破裂时间(break-up time,BUT)、基础泪液分泌试验I(Schirmer I test,SIt)、角结膜荧光素(fluorescent,fl)染色、虎红(rose bangle,rb)染色检查等。对资料齐备并确诊为干眼的102例(204眼)患者的问卷资料以及检查资料进行分析。结果:102例患者中干涩症状者54例(52.9%),异物感者52例(51.1%),眼疲劳者44例(43.1%)。干眼病人中合并有BUT异常的为76例(74.5%),虎红染色异常的为59例(57.8%),荧光素染色异常的为42例(41.2%),SIt异常的为18例(17.6%)。结论:在干眼的诸多症状中,干涩感、异物感、眼疲劳三大症状发生率最高。BUT缩短是门诊干眼患者最主要的体征。

Distribution of Reinforcement in Tensile Flanges of Concrete T-shape Continuous Beam

In this paper the analysis of tensile stress distribution in flexural continuous T- beam has been presented. The observed damages in carrying deck of RC bridge over the Wieprz River in Baranow indicate that over pillar zones are not protected enough. The results of numerical analysis have shown that tensile stress in T- section beam appears not only in a web but in flanges as well. Thus reinforcing bars should be distributed within the whole effective width. This fact is mentioned in building codes, for example, in Eurocode 2： ＂Design of concrete structures＂, both in part 1.1 ＂General rules and rules for building＂ and in part 2 ＂Reinforced and prestressed concrete bridges＂, but there are not detailed rules how to place the bars in flanges of T-section.

论东南亚大陆T字形环的起源

T字形环是公元前2300年至500年在古代中国与东南亚大陆广泛分布的一种器物。新的研究表明,东南亚大陆的T字形环是在跨区域文化交流与互动的背景下独立起源的,中国早期的T字形环对东南亚大陆T字形环的出现并无明显影响。东南亚大陆目前最早的T字形环在公元前2500年左右出现在越南北部马河流域的华禄文化遗址,并短时间内在红河流域的冯原文化迅速发展,至青铜时代已遍布东南亚大陆,进入铁器时代以后逐渐消亡。