scholarly journals The influence of steel yielding of main reinforcement on bending capacity of beams strengthened with CFRP strips

2013 ◽  
Vol 12 (1) ◽  
pp. 085-090
Author(s):  
Przemysław Bodzak

This paper describe tests on RC beams strengthened with externally bounded CFRP plates. A total of four PCC beams with rectangular 15×30cm cross section and 300cm clear span were manufactured and tested in four-point flexure with 100cm constant moment region. Low compressive strength of concrete fck about 20MPa and middle reinforcement ratio – 0,0075 were used. Different yield strengths of steel, from 360MPa to 1860MPa, were chosen as experimental variables. All the beams were strengthened with one CFRP strip measuring 5×1,2cm. The specimen failed at various load and at various ultimate strains of CFRP strips. It was generally observed that both the moment capacity and the ultimate strains grew with the increase of steel yielding strength. It could be deducted that in many cases reaching the yielding steel strength activates the deboning of FRP strips.

Author(s):  
Bogdan I. BEDELEAN ◽  
Iosif NECULĂEȘ ◽  
Cosmin G. SPÎRCHEZ ◽  
Sergiu RĂCĂȘAN

In this work, the influence of the number of dowels and the option to place the dowels in the cross section of part on the bending moment capacity of heat-treated wood dowel joints was analysed. The joints, which were made of heat-treated ash, were tested by means of a universal testing machine.The ultimate failure load and the moment arms were used to figure out the bending moment capacity of the joints loaded in compression or in tension. The number of dowels affected the tensile strength of the L-shaped heat-treated wood joints. The modality to place the dowels in the cross section of rail, namely, in collinearity or in a triangular shape, did not significantly affect the strength of the heat-treated wood dowel joints.


Author(s):  
Nobuhisa Suzuki ◽  
Joe Kondo ◽  
Shigeru Endo ◽  
Nobuyuki Ishikawa ◽  
Mitsuhiro Okatsu ◽  
...  

Validation of finite element modeling to predict bending capacity of linepipes and effects of geometric imperfection on the bending capacity are presented. A bending test of an X80 linepipe was conducted to discuss the validation and investigate the effects. The geometric imperfection of the linepipe about the outside diameter, the wall thickness and the longitudinal blister of the linepipe was measured in the round. Consequently, the results obtained by FEA taking into account the geometric imperfection present good agreement with the experimental data. And the moment capacity is virtually independent of the geometric imperfection however the strain capacity of the linepipe is quite susceptible to the geometric imperfection.


2013 ◽  
Vol 7 (1) ◽  
pp. 146-157 ◽  
Author(s):  
Constantinos B. Demakos ◽  
Constantinos C. Repapis ◽  
Dimitrios Drivas

The beneficial effect of a composite material anchorage system (CMAS) upon the ductility and load capacity of reinforced concrete (RC) beams strengthened either with glass (GFRP) or carbon (CFRP) fabrics was investigated. The anchorage system consisted of U-shaped GFRP or CFRP strip (U-strip) at end of FRP. The U-strips were bonded around the beam section and further anchored by two tufts of glass fibres, each of them embedded at the opposite beam face and specifically in the region of compression zone of the beam web. Experimental evaluations in simply supported lightly reinforced concrete (RC) beams strengthened with one GFRP or a CFRP sheet anchored at its ends by the composite anchorage have shown that their bending capacity has increased by 8% and 17%, respectively, in relation to the capacity attained in similar RC strengthened beams without anchorage. On the other hand, their ductility was improved by an amount of 94% and 37%, respectively.


2020 ◽  
Vol 3 (2) ◽  
pp. 97-106
Author(s):  
Jaya Permana ◽  
M. Muhtaris ◽  
Eka Susanti ◽  
Yanisfa Yanisfa

Double reinforcement beam design, increasing the compressive reinforcement can increase the flexural capacity moment and ductility of concrete beams. This helps planners to improve flexural capacity moment with minimal dimensions, that are still acceptable in terms of aesthetics. The purpose of this study is to know how much influence the increasing compressive reinforcement can increase the flexural capacity moment and ductility of concrete beams. Experimental research with beam specimens 20x20x60 cm, 2D16 tensile reinforcement, fc’ 25 mpa and fy 320 mpa. With a ratio of compressive reinforcement to tensile reinforcement of 0.14; 0.25 and 0.59. Flexural strength testing uses flexible loading with a roll-pined joint. The process of load reading is yield phase until ultimate phase. The results of the analysis show an uses of increasing compressive reinforcement can increase the moment of flexural capacity and ductility. The addition of compressive reinforcement reached 25% from tensile reinforcement, can increase the moment of bending capacity by 4.47%, but uses compressive reinforcement reached 50% of tensile reinforcement, only increasing the bending moment capacity of 1.43%. For ductility, uses compressive reinforcement reaches 25% from tensile reinforcement, can increase ductility by 19.73% and an increase of 26.17% by adding compressive reinforcement up to 50% of tensile reinforcement. From these results it appears that the more improvements added, the more the ductility increases and the less the moment the flexural capacity increases.


2010 ◽  
Vol 37 (6) ◽  
pp. 842-854 ◽  
Author(s):  
Y. I. Elbahy ◽  
M. A. Youssef ◽  
M. Nehdi

This paper investigates the load–deflection behaviour of shape memory alloy (SMA) reinforced concrete (RC) beams through a parametric study. The effects of the cross-section height, cross-section width, reinforcement ratio, reinforcement modulus of elasticity, and concrete compressive strength were considered. The sectional analysis methodology was adopted to predict the moment–curvature relationship for the considered sections. Deflection was then estimated using the moment–area method. The applicability of this method for SMA RC beams was demonstrated through comparisons with available experimental results. Based on the results of the parametric study, an assessment of the available models for deflection analysis of SMA RC beams was conducted. The accuracy and reliability of the different models were evaluated, and suitable models were recommended. A companion paper provides the development of an artificial intelligence based model that can predict the deflection of SMA RC beams more accurately than existing models.


Author(s):  
Lakshmi Thangasamy ◽  
◽  
Gunasekaran Kandasamy ◽  

Many researches on double skin sandwich having top and bottom steel plates and in between concrete core called as steel-concrete-steel (SCS) were carried out by them on this SCS type using with different materials. Yet, use of coconut shell concrete (CSC) as a core material on this SCS form construction and their results are very limited. Study investigated to use j-hook shear studs under flexure in the concept of steel-concrete-steel (SCS) in which the core concrete was CSC. To compare the results of CSC, the conventional concrete (CC) was also considered. To study the effect of quarry dust (QD) in its place of river sand (RS) was also taken. Hence four different mixes two without QD and two with QD both in CC and CSC was considered. The problem statement is to examine about partial and fully composite, moment capacity, deflection and ductility properties of CSC used SCS form of construction. Core concrete strength and the j-hook shear studs used are influences the moment carrying capacity of the SCS beams. Use of QD in its place of RS enhances the strength of concrete produced. Deflections predicted theoretically were compared with experimental results. The SCS beams showed good ductility behavior.


Author(s):  
Julian F. Hallai ◽  
Stelios Kyriakides

In several offshore applications hot-finished pipe that often exhibits Lu¨ders bands is bent to strains of 2–3%. Lu¨ders banding is a material instability that leads to inhomogeneous plastic deformation in the range of 1–4%. It can precipitate structural instabilities and collapse of the pipe. Experiments and analysis are used to study the interaction of the prevalent structural instabilities under bending with Lu¨ders banding, with the objective of providing guidance to the designer. Pure bending experiments on tubes of various D/t values reveal that Lu¨ders bands result in the development of inhomogeneous deformation in the structure, in the form of coexistence of two curvature regimes. Under rotation controlled bending, the higher curvature zone(s) gradually spreads while the moment remains essentially unchanged. For relatively low D/t tubes with relatively smaller Lu¨ders strain, the whole tube eventually is deformed to the higher curvature, subsequently entering the usual hardening regime where it continues to deform uniformly until the expected limit state is reached. For higher D/t tubes and/or for materials with longer Lu¨ders strain, the structure collapses during the inhomogeneous deformation regime. This class of problems is analyzed using 3D finite elements and an elastic-plastic constitutive model with an up-down-up material response. It will be demonstrated that the solution procedure followed can simulate the experiments with consistency.


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