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Theoretical analysis of natural frequency of externally prestressed concrete beam based on rigidity correction 被引量:3
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作者 Hui-xia Xiong1,2, Yao-ting Zhang11.School of Civil Engineering & Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China 2.Department of Civil Engineering, Nanyang Institute of Technology, Nanyang 473004, China. 《Journal of Pharmaceutical Analysis》 SCIE CAS 2009年第1期31-35,共5页
A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase w... A dynamic test on externally prestressed simply supported concrete beams separately with three typical types of tendon distributions was conducted. The results show that the natural frequencies of the beams increase with the increase in the prestressing force at the tensioning stage, and the natural frequencies decrease after the cracks occur in the beams. Following the calculation formula of natural frequency of externally prestressed beam, which was reported in a literature, the natural frequencies of the experimental beams are calculated, and big errors are found between the test results and the calculated ones of natural frequency values. As a result, this paper has tried to adopt two methods to correct the rigidity parameter of the concrete beam in the formula for natural frequency calculation, and to use the corrected formula to calculate the frequencies of the experimental beams. The calculation results indicate a good consistency with the experimental ones, which verifies the feasibility of the corrected formula. 展开更多
关键词 externally prestressed concrete beam natural frequency rigidity correction regression analysis
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Effectiveness of external prestressing in enhancing the non-ductile hanger failure mechanism in reinforced concrete inverted T-beams
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作者 Ahmed M.ATTA Reda N.BEHIRY Mohammed I.HARAZ 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2024年第7期1050-1065,共16页
Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast stringers.Inverted T-beams,contrary to practice with conventional beams,are loaded on the flanges upper surface.... Recently,inverted T-beams have been used in reinforced concrete(RC)bridges to support transverse precast stringers.Inverted T-beams,contrary to practice with conventional beams,are loaded on the flanges upper surface.This loading configuration causes hanger failure due to the generation of vertical tensile stresses near the bottom of the web.The key purpose of this study is to investigate the efficiency of vertical external prestressing stainless-steel bars in mitigating non-ductile hanger failure in reinforced concrete inverted T-beams.An experimental study on six inverted-T beams,including two un-strengthened specimens,was carried out.The study showed that the value of the prestressing level had a considerable impact on the performance of hanger mechanism in relation to crack pattern,ultimate loads,cracking behavior,load-deflection,strains,and ductility.The experimental results indicated that the suggested method for strengthening inverted T-beams had efficacy in reducing the seriousness of the non-ductile hanger failure and resulted in a strength increase of up to 53% when compared to that of the un-strengthened specimen.Additionally,two analytical models for estimating the hanger capacity and the average crack width of the strengthened RC inverted T-beams were proposed.The models that were proposed exhibited a high degree of agreement with the experimental results. 展开更多
关键词 RC bridges inverted T-beams strengthening hanger failure external prestressing
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Experimental and theoretical analysis on the natural frequency of external prestressed concrete beams 被引量:1
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作者 熊辉霞 《Journal of Chongqing University》 CAS 2008年第4期317-323,共7页
Analyses and computations of the natural frequencies of external prestressed concrete structures are the bases for studying the dynamic properties of such structures. We carded out dynamic tests on three types of exte... Analyses and computations of the natural frequencies of external prestressed concrete structures are the bases for studying the dynamic properties of such structures. We carded out dynamic tests on three types of external simply supported beams, pulling the beams gradually. Then vertical loads were applied to the beams while the frequencies and related coefficients were measured at every step. We calculated natural frequencies and the results indicate that natural frequencies increase as the prestressing force rises in the pre-crack stage, and decrease significantly during the post-crack stage. Substantial incoincidences exist between the calculated and experimental results for the frequency and its tendency to changel Based on the experimental results, we modified the stiffness and other parameters in the equations. The results calculated using the modified equations agree with experimental results well, so the modified eauations can be used nractically. 展开更多
关键词 natural frequency external prestressed concrete beams dynamic property stiffness modification
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Shear behavior of ultra-high-performance concrete beams prestressed with external carbon fiber-reinforced polymer tendons 被引量:1
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作者 Li JIA Zhi FANG +2 位作者 Maurizio GUADAGNINI Kypros PILAKOUTAS Zhengmeng HUANG 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2021年第6期1426-1440,共15页
The ultra-high-performance concrete(UHPC)and fiber-reinforced polymer(FRP)are well-accepted high-performance materials in the field of civil engineering.The combination of these advanced materials could contribute to ... The ultra-high-performance concrete(UHPC)and fiber-reinforced polymer(FRP)are well-accepted high-performance materials in the field of civil engineering.The combination of these advanced materials could contribute to improvement of structural performance and corrosion resistance.Unfortunately,only limited studies are available for shear behavior of UHPC beams reinforced with FRP bars,and few suggestions exist for prediction methods for shear capacity.This paper presents an experimental investigation on the shear behavior of UHPC beams reinforced with glass FRP(GFRP)and prestressed with external carbon FRP(CFRP)tendons.The failure mode of all specimens with various shear span to depth ratios from 1.7 to 4.5 was diagonal tension failure.The shear span to depth ratio had a significant influence on the shear capacity,and the effective prestressing stress affected the crack propagation.The experimental results were then applied to evaluate the equations given in different codes/recommendations for FRPreinforced concrete structures or UHPC structures.The comparison results indicate that NF P 18-710 and JSCE CES82 could appropriately estimate shear capacity of the slender specimens with a shear span to depth ratio of 4.5.Further,a new shear design equation was proposed to take into account the effect of the shear span to depth ratio and the steel fiber content on shear capacity. 展开更多
关键词 BEAM external prestressing ultra-high-performance concrete fiber-reinforced polymers shear behavior design equation
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