scholarly journals Retrofitting of Reinforced Concrete Beams Using a Fiberglass Jacketing System

2021 ◽  
Vol 4 (1) ◽  
pp. 44
Author(s):  
Titik P. Artiningsih ◽  
Lirawati L. ◽  
Navi Helmi
Keyword(s):  
Experimental Testing ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Building Collapse ◽  
Load Factors ◽  
Bending Load ◽  
Loading System ◽  
Earthquake Load ◽  
Bending Loads

Building collapse that occurred mostly caused by structure failure in containment earthquake load. Factors that lead to the failure of the beam, among others is beam planning that does not calculate ductility or restraint, resulting decline of beams performance. One way to improve beam strength and ductility are to retrofit the beam by wrapping beams using fiberglass. Research aims to discover the increase amount of bending load capacity from concrete beam that has been retrofitted using jacketing fiberglass. Experimental testing was carried out on beam specimens with a cross section size of 150x200 mm and a length of 1400 mm. Three beam specimens were subjected to bending loads with a three point loading system, with different levels of damage, namely BL1 with collapse at level-1, BL2 at level-2, and BL0 at level-5 as a comparison. Then the BL1 and BL2 were retrofitted by being coated with 2 layers of fiberglass which were glued using epoxy resin. Beams BL-1 and BL-2 are then subjected to a bending test again until they reach level-5 collapse. The test results showed that retrofitted beams were able to increase flexural strength, BL-1 increased 115.15% from the original load and BL-2 increased 52.27% from the original load.

Post-Buckling Failure Modes of X65 Steel Pipe: An Experimental and Numerical Study

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Nima Mohajer Rahbari ◽  
Mengying Xia ◽  
Xiaoben Liu ◽  
J. J. Roger Cheng ◽  
Millan Sen ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Cross Section ◽  
Failure Modes ◽  
Bending Test ◽  
Bending Load ◽  
Post Buckling ◽  
X65 Steel ◽  
Bending Loads ◽  
Buckling Failure ◽  
Longitudinal Strains

In service pipelines exhibit bending loads in a variety of in-field situation. These bending loads can induce large longitudinal strains, which may trigger local buckling on the pipe's compressive side and/or lead to rupture of the pipe's tensile side. In this article, the post-buckling failure modes of pressurized X65 steel pipelines under monotonic bending loading conditions are studied via both experimental and numerical investigations. Through the performed full-scale bending test, it is shown that the post-buckling rupture is only plausible to occur in the pipe wall on the tensile side of the wrinkled cross section under the increased bending. Based on the experimental results, a finite element (FE)-based numerical model with a calibrated cumulative fracture criterion was proposed to conduct a parametric analysis on the effects of the internal pressure on the pipe's failure modes. The results show that the internal pressure is the most crucial variable that controls the ultimate failure mode of a wrinkled pipeline under monotonic bending load. And the post-buckling rupture of the tensile wall can only be reached in highly pressurized pipes (hoop stress no less than 70% SMYS for the investigated X65 pipe). That is, no postwrinkling rupture is likely to happen below a certain critical internal pressure even after an abrupt distortion of the wrinkled wall on the compressive side of the cross section.

RETROFITTING PERFORMANCE OF REINFORCED CONCRETE ONE WAY SLAB

2016 ◽  
Vol 78 (5-3) ◽  
Author(s):  
Norliyati Mohd Amin ◽  
Nur Aqilah Aziz ◽  
Ilya Joohari ◽  
Anizahyati Alisibramulisi
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Strength Performance ◽  
Concrete Crack ◽  
Reinforced Polymer ◽  
Structural Capacity

Cracks in concrete structure have always been a big threat on the strength of the concrete. Crack is one of the common deterioration observed in reinforced concrete beams and slabs. Concrete cracking is a random process, highly variable and influenced by many factors. To restore the structural capacity of the concrete damages, retrofitting and strengthening are required. There are several techniques that are used for retrofitting and strengthening reported in the literature [1], [2], [3]. This paper investigates the strength performance of retrofitting and strengthening methods of reinforced concrete one-way slab. Flexural bending test are performed on three different concrete slab of size 1000 mm x 500 mm x 75 mm. The methods that are used for retrofit are epoxy injection and patching and for the strengthening is lamination of carbon fiber reinforced polymer. The slabs were loaded to a certain stage where the cracks were formed for retrofitting and strengthening procedure. The achieved failure mode and load capacity of the concrete slab were observed. The repaired techniques for restoring and improving the structural capacity of cracked concrete slabs were analyzed. The ultimate load achieved for the epoxy injection laminate was 19.60 kN followed by CFRP laminate and patching that were 17.64 kN and 17.03 kN respectively. While the deflection value for the three specimens were 14.42 mm, 4.49 mm and 7.036 mm.  

scholarly journals Analytical Analysis of Distribution of Bending Stresses in Layers of Plywood with Numerical Verification

2019 ◽  
Vol 70 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Andrzej Makowski
Keyword(s):  
Bending Strength ◽  
Plate Theory ◽  
Load Capacity ◽  
Bending Test ◽  
Accurate Estimation ◽  
Numerical Verification ◽  
Classical Plate Theory ◽  
Bending Load ◽  
Bending Stresses ◽  
Distribution Of Stresses

The study presents methods for accurate estimation of bending stresses in the 3-point flexural bending test of plywood, i.e. a wood-based laminate with an alternate crosswise ply configuration. The characteristic bending strength (MOR) and mean modulus of elasticity (MOE) of standard beech plywood was determined using European Standard bending tests EN 310. Correlations were determined between empirically determined bending moduli of the plywood and material moduli of the veneer layer. Calculations were conducted based on the classical plate theory for thin panels comprising the theory of elasticity including the Kirchhoff-Love hypothesis. Rigidity of individual layer was established theoretically in the axial configuration of transformed rigidity matrix values. Numerical laminate models were developed and simulation tests were conducted. Results of experimental and analytical studies were verified using the Finite Element Method (FEM). Analyses were performed in two plywood cross-band arrangement variants. An analysis of the distribution of stresses in individual layers of plywood used an analytical and numerical method assuming the plywood specimen to be a rhombic-anisotropic material. It was found that the bending load capacity of plywood depends on the configuration of individual layers (veneers). Values of stresses originating from bending do not only depend on the distance of the considered plywood layer from the middle layer but also on stiffness in the direction of operating stresses. Bending strength varies in individual directions of the plywood panel. Therefore, the distribution of stresses in individual layers differs from that resulting from the stress distribution for homogeneous isotropic materials. Results are presented in the form of tables, bitmaps, graphs and photographs. The tests were conducted based on the BFU-BU-18 standard beech plywood thickness of 18 mm.

scholarly journals Openings Effect on the Performance of Reinforced Concrete Beams Loaded in Bending and Shear

2020 ◽  
Vol 10 (2) ◽  
pp. 5352-5360
Author(s):  
F. El Ame ◽  
J. N. Mwero ◽  
C. K. Kabubo
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Concrete Beams ◽  
Load Capacity ◽  
Maximum Load ◽  
Reinforced Concrete Beams ◽  
Engineering Properties ◽  
Bending Test ◽  
Shear Cracks ◽  
Codes Of Practice

Transverse openings are often provided to reinforced concrete beams to accommodate utility ducts and pipes. This technique is usually adopted to avoid the creation of dead space in structures caused by extended dropped ceilings and leads to significant cost saving. On the other hand, the provision of openings through a beam creates a reduction in its strength and affects serviceability. In this study, ten reinforced concrete beams were cast using C30 concrete. Material characterization and engineering properties tests were carried out to ensure compliance with the requirements provided by the codes of practice. The effect of vertical positioning and size of openings was investigated through subjecting the beams to a four-point bending test after 28 days of curing. Maximum load capacity, first cracking load, and deflections at mid-span were recorded and crack pattern and failure mode were evaluated. Test data showed that openings of depth greater than 0.4d significantly affect the beams’ strength and lead to earlier cracking, while the failure mode remains essentially the same, a diagonal tension crack through the opening except for opening of 0.5d size where the failure occurred by a sudden formation of two independent shear cracks above and below the opening. When holes were located above the centroid of the section, the beams exhibited a lesser deflection characterized by the absence of plastic deformation. Furthermore, a significant reduction in strength was recorded compared to cases where the positioning of openings was in tension chords. This was validated using equations from the ACI code of reinforced concrete design.

scholarly journals Experimental investigation on the flexural and post-cracking behaviour of geogrid-reinforced concrete overlays

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
N. S. Correia ◽  
G. M Dalfre
Keyword(s):  
Experimental Investigation ◽  
Reinforced Concrete ◽  
Portland Cement ◽  
Concrete Beam ◽  
Load Capacity ◽  
Mouth Opening ◽  
Energy Performance ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Concrete Overlays

Innovative materials are on the rise as alternatives to steel reinforcement in concrete structures. Recently, the use of polymeric geogrids as reinforcement elements has expanded into Portland cement concrete (PCC) overlays rehabilitation. Research conducted to date has indicated that the use of geogrids as reinforcement in concrete pavements shows both post cracking ductility and superior load capacity. Although this topic is not so explored in the literature, the use of geogrids in thin concrete overlays, pathway, pedestrian sidewalks and floating slabs is promising and gives a new employment area for the use of geogrid reinforcements. This paper presents an experimental investigation on the flexural behaviour, post-cracking and fracture energy performance of geogrid-reinforced concrete beams under four-point bending test. Different geogrids were embedded at one-third depth (from bottom) of concrete beam specimens (500 × 150 × 150 mm). The PCC mix was prepared using Ordinary Portland Cement (OPC grade 53) with compressive strength of 40 MPa. Results confirmed that the flexural performance and post-cracking resistance of the concrete beam specimens could be enhanced by the presence of geogrids, as evidenced by load-deflection response, crack mouth opening displacements and change in failure mode. Triaxial geogrids showed 11% increase in flexural strength of concrete beam, highlighting the potential benefits of geogrids reinforcements in PCC overlays.

scholarly journals Finite element analysis of reinforced concrete deep beam with large opening

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Elsayed Ismail ◽  
Mohamed S. Issa ◽  
Khaled Elbadry
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
The Other ◽  
Deep Beam ◽  
Web Openings ◽  
Design Load ◽  
Large Opening

Abstract Background A series of nonlinear finite element (FE) analyses was performed to evaluate the different design approaches available in the literature for design of reinforced concrete deep beam with large opening. Three finite element models were developed and analyzed using the computer software ATENA. The three FE models of the deep beams were made for details based on three different design approaches: (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978), (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006), and Strut and Tie method (STM) as per ACI 318-14 (ACI318 Committee, Building Code Requirements for Structural Concrete (ACI318-14), 2014). Results from the FE analyses were compared with the three approaches to evaluate the effect of different reinforcement details on the structural behavior of transfer deep beam with large opening. Results The service load deflection is the same for the three models. The stiffnesses of the designs of (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and STM reduce at a load higher than the ultimate design load while the (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) reduces stiffness at a load close to the ultimate design load. The deep beam designed according to (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) model starts cracking at load higher than the beam designed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) method. The deep beam detailed according to (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) and (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) failed due to extensive shear cracks. The specimen detailed according to STM restores its capacity after initial failure. The three models satisfy the deflection limit. Conclusion It is found that the three design approaches give sufficient ultimate load capacity. The amount of reinforcement given by both (Mansur, M. A., Design of reinforced concrete beams with web openings, 2006) and (Kong, F.K. and Sharp, G.R., Magazine of Concrete Res_30:89-95, 1978) is the same. The reinforcement used by the STM method is higher than the other two methods. Additional reinforcement is needed to limit the crack widths. (Mansur, M. A., Design of reinforced concrete beams with web openings, (2006)) method gives lesser steel reinforcement requirement and higher failure load compared to the other two methods.

Experimental Testing of Fiber Reinforced Polymer-Concrete Composite Beam

2010 ◽  
Vol 168-170 ◽  
pp. 549-552
Author(s):  
Yan Lei Wang ◽  
Qing Duo Hao ◽  
Jin Ping Ou
Keyword(s):  
Composite Beam ◽  
Experimental Testing ◽  
Coarse Sand ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Polymer Concrete ◽  
Fiber Reinforced ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Box Beam

A new form of fiber reinforced polymer (FRP)-concrete composite beam is proposed in this study. The proposed composite beam consists of a GFRP box beam combined with a thin layer of concrete in the compression zone. The interaction between the GFRP beam and the concrete was obtained by bonding coarse-sand on the top flange of the GFRP beam. One GFRP box beam and one GFRP-concrete composite beam were investigated in four-point bending test. Load-deflection response, mid-span longitudinal strain distributions and interface slip between GFRP beam and the concrete for the proposed composite beam were studied. Following conclusions are drawn from this study: (1) the stiffness and strength of the composite beam has been significantly increased, and the cost-to-stiffness ratio of the composite beam has been drastically reduced comparing with GFRP-only box beam; (2) a good composite action has been achieved between the GFRP beam and the concrete; (3) crushing of concrete in compression defines flexural collapse of the proposed composite beam..

Nondestructive Measurement of In-Plane Residual Stress in Silicon Strips

1999 ◽  
Vol 591 ◽  
Author(s):  
Tieyu Zheng ◽  
Steven Danyluk
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Large Deflection ◽  
Thin Plates ◽  
Nondestructive Measurement ◽  
Three Point Bending ◽  
Phase Stepping ◽  
Bending Load ◽  
Bending Loads ◽  
Processing Techniques

ABSTRACTThis paper reports the development of a shadow moiré technique to measure the in-plane residual stresses of thin, flat strips. This is an extension of prior work on the measurement of in-plane residual stresses in silicon plates and wafers. Phase stepping shadow moir6 and digital image processing techniques are employed to measure the deflections of the silicon plate specimens subjected to three-point-bending at several different loads. The measured deflections over the area of the silicon plates are fitted with an equation represented by a 2-D polynomial. With the theory of thin plates with large deflection, the fitting coefficients are used to extract the in-plane stresses at the different bending load. The residual stress is resolved by linear regression of the in-plane stresses versus bending loads.

Sinusoidal Torsional Buckling of Bars of Angle Section Under Bending Loads, as a Problem in Plate Theory

1951 ◽  
Vol 18 (3) ◽  
pp. 285-292
Author(s):  
H. J. Plass
Keyword(s):  
Infinite Series ◽  
Plate Theory ◽  
Ritz Method ◽  
Compressive Load ◽  
Series Solutions ◽  
Torsional Buckling ◽  
Bending Load ◽  
Angle Section ◽  
Bending Loads

Abstract Timoshenko has applied plate theory to each leg of an angle-section bar to determine the critical compressive load needed to cause sinusoidal torsional buckling. In this paper his idea is used to calculate the critical bending load needed to cause sinusoidal torsional buckling of an angle bar. The bending is assumed to be applied so that the extreme fibers of the angle are in compression, the vertex in tension. Approximate results are first obtained by means of the Rayleigh-Ritz method. The approximate deflection functions from which the energy terms are computed are based upon certain infinite-series solutions. After having obtained approximate results, exact values are obtained, using the approximate values as a guide to limit the amount of calculation. The results of this calculation are shown in Fig. 5, where they are compared with those predicted by bar theory. Differences between the two theories become more noticeable as the bar becomes short compared to its flange width. It is found that the critical bending load becomes larger very rapidly as the ratio of length to width of the flanges decreases. Bar theory predicts no such increase. The reason for this difference is explained.

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