Flexural Strength Of Beams Research Articles

Behavior of cold-formed steel elliptical hollow sections subjected to bending

This paper presents the experimental and numerical investigation on the behavior of cold-formed steel elliptical hollow section beams. In the test program, a total of 20 beam tests was conducted. Four elliptical section series with the nominal cross-section aspect ratio ranging from 1.65 to 3 were bent about the major and minor axes in both three-point and four-point bending configurations. Finite element models were established to replicate the beam tests numerically. Based upon the validated model, extensive parametric study was conducted on 235 beam specimens to study the behavior of cold-formed steel elliptical hollow sections subjected to bending. The results obtained from experimental and numerical investigation were used to assess the existing design methods and to propose modified design methods for cold-formed steel elliptical hollow section beams. It should be noted that the current design codes do not cover the design of elliptical hollow section beams. The flexural strengths of beams were compared with the design strengths predicted by the equivalent diameter and equivalent rectangular section methods proposed by previous researchers, the traditional design methods using equivalent diameter as well as the Direct Strength Method and the Continuous Strength Method. The applicability and reliability of these design methods were assessed. The results indicate that the existing design methods are not capable to predict the flexural strengths of cold-formed steel elliptical hollow section beams in accurate and reliable manner. In this study, the modified Direct Strength Method and Continuous Strength Method are proposed, which provide accurate and reliable flexural strength predictions.

Scale Effect in Ice Flexural Strength

Ice flexural strength is an important parameter in the assessment of ice loads on the hulls of ice-class ships, sloped offshore structures, and sloped bridge piers. While scale effects in compressive ice strength are well known, there has been debate as to the extent of scale effects in ice flexural strength. To investigate scale effects during flexural failure of both freshwater and saline ice, a comprehensive up-to-date database of beam flexural strength measurements has been compiled. The database includes 2073 freshwater ice beam tests with beam volumes between 0.00016 and 2.197 m3, and 2843 sea ice beam tests with volumes between 0.00048 and 59.87 m3. The data show a considerable decrease in flexural strength as the specimen size increases, when examined over a large range of scales. Empirical models of freshwater ice flexural strength as a function of beam volume, and of saline ice as function of beam and brine volumes have been developed using regression analysis. For freshwater ice, the scale-dependent flexural strength is given as: σf=839(V/V1)−0.13 For sea ice, the dependence of flexural strength has been modeled as: σ=1324(V/V1)−0.054e−4.969vb. Probabilistic models based on the empirical data were developed based on an analysis of the residuals, and can be used to enhance probabilistic analysis of ice loads where ice flexural strength is an input.

Effect of Water-Cement Ratio on Flexural Strength of RC Beams Made with Partial Replacement of Coarse Aggregates with Coarse Aggregates from Old Concrete

This research paper presents an experimental evaluation of the effect of water-cement ratio on the flexural strength of reinforced concrete beams made with 50% replacement of coarse aggregates with recycled concrete aggregates (RCA). 72 reinforced concrete beams were cast using 0.54, 0.6, 0.65 and 0.70 water-cement ratio. In each ratio, 12 beams were cast using RCA and 3 beams were cast using all-natural coarse aggregates (NCA). Beams were cured for 7 and 28 days. After curing, all beams were tested with central point load in a universal load testing machine. From the obtained results, it is observed that the maximum reduction in flexural strength of RCA beams is about 28% when compared to the 0.54 w/c ratio beams of the same group and 31.75% in comparison to NCA beams cast with same w/c ratio. The maximum deflection and average strain in beams remained within limits. The observed cracking pattern shows shear failure of all beams.

Effect of Water-Cement Ratio on Flexural Strength of RC Beams Made with Partial Replacement of Coarse Aggregates with Coarse Aggregates from Old Concrete

Effect of Water-Cement Ratio on Flexural Strength of RC Beams Made with Partial Replacement of Coarse Aggregates with Coarse Aggregates from Old Concrete

Flexural tests of masonry beam with and without reinforced bar

Behaviour of reinforced masonry has been studied experimentally to determine its strength potential. The increase in either compressive or tensile strength of masonry is possible due to the existence of rebar or wire mesh. The research is carried out to determine the effect of steel rebar on flexural strength of reinforced masonry beam using local brick. The square hollow masonry beams of 330x330mm with and without reinforced bar were tested in the laboratory to determine the load and deflection curves and bending strength. The rebar was located at the centre of beam’s cross section and left unbounded. Mechanical properties of masonry’s constitute were also determined. It was found that the flexural strength of beams with rebar of 22 mm diameter was greater 11 times than that of beam without rebar. However, that strength was only 1.6 times due to the weaker end connections of the beam to the rebar. Flexural strength of reinforced masonry beam with 22 mm rebar was greater 2.7 times compared to the beam using a rebar diameter of 16 mm.

RA V9 N1, Mensaje del Editor en Jefe (Enero - Abril 2019)

Revista Latinoamericana de Control de Calidad, Patologia y Recuperacion de la Construccion http://www.revistaalconpat.org Es motivo de satisfaccion y alegria para el equipo de la Revista ALCONPAT ver publicado el primer numero de nuestro segundo ano al aire. El objetivo de la Revista ALCONPAT (RA) es la publicacion de casos de estudio relacionados con los temas de nuestra asociacion, o sea control de calidad, patologia y recuperacion de las construcciones motivando desde luego la presentacion de investigaciones basicas o aplicadas que pudiesen tener aplicacion con los casos de estudio. En este V2N1, iniciamos con nuestro articulo especial invitado, procedente de Portugal , donde Fernando Branco presenta una nueva filosofia para proyectar mas de 100 anos de vida de servicio en puentes. Fernando discute con propiedad la aplicacion de esta metodologia por primera vez en el Puente Vasco de Gama que fue proyectado para durar 120 anos. Fernando discute con claridad la fase de proyecto, de construccion y de gestion durante la vida de servicio. Entre los retos que nos presenta la industria de la construccion y la vida de servicio de las estructuras se encuentra desde luego la habilidad de producir cambios de uso para darle valor o extender la vida de una estructura. Este es el caso de un antiguo hotel transformado en banco que Alfredo Payer y sus colegas de Argentina describen con detalle desde la modelizacion numerica y analisis estructural de la estructura antigua y la refuncionalizada hasta el mismo procedimiento de construccion. Sin duda una exitosa rehabilitacion. En muchas ocasiones nos enfrentamos a verdaderos retos de inspeccion y restauracion que por sus caracteristicas pueden ser experiencias unicas. Muchas de estas no serian posibles sin un conocimiento adecuado del concreto y sus propiedades. Por ello, en este numero se abordan temas relacionados con el control de calidad que coadyuvan al buen entendimiento de la tecnologia del concreto y del capital humano. En el tercer articulo, Romel Solis y colegas de Mexico , presentan un caso como el que podria ocurrir en un clima calido, donde analizan la maxima resistencia de diseno que podria obtenerse con agregados triturados de alta absorcion. Mediante un procedimiento riguroso encuentran que 500 kg/cm2 es el valor maximo a obtener. Como nota curiosa, en sitios donde es comun el uso de agregados triturados de piedra caliza y el clima calido en Mexico se tenia la creencia de no poder alcanzar resistencias mecanicas mayores a 300 kg/cm2, tema que desde luego desmitifica el trabajo de Solis y sus colegas. En el cuarto articulo, Edith Cordova presenta un caso de El Salvador donde se logra documentar como el entrenamiento y supervision son clave para que el capital humano se convierta en un factor determinante en la calidad de las obras. Particularmente llama la atencion el uso de herramientas educativas y tecnologicas que se utilizan en este caso para llegar a su objetivo. El quinto articulo de RAV2N1 procede de Espana y en el Vicente Alegre y colegas muestran en forma por demas didactica el caso del colapso de la cubierta metalica de un polideportivo en donde ocurrieron problemas patologicos singulares pero que ya se habian presentado en otras obras. El sexto y ultimo articulo de esta edicion procede de Brasil , donde Santor y colegas presentan la influencia de los materiales de proteccion en la resistividad del concreto Cada numero de RA busca balancear la participacion de temas afines al objeto social de la ALCONPAT, por lo que la ingenieria estructural, el control de calidad, la inspeccion, diagnostico y reparacion se dan cita en cada numero desde los diferentes paises que conforman nuestra sociedad. Por el Consejo Editorial Pedro Castro Borges Editor en Jefe

Flexural and Short beam shear strength analysis of symmetrical GFRP composites reinforced with MWCNTs having notches

The background of the work is experimental and micromechanical investigation of specimen samples having notch at a particular location from the central axis on Short Beam Shear Strength (SBSS) and Flexural strength of prepared Glass fiber reinforced polymer (GFRP) composites doped with Multi-wall carbon nanotubes (MWCNTs). The GFRP used is fabricated using hand lay-up technique assisted by vacuum bagging method and is symmetrical with eight layers of 4.0 mm thickness in total. The doping wt.% of MWCNTs used were 0 (neat), 1, 2, 3 and 4. The testing was carried out in Universal Testing Machine (UTM) using ASTM D2344 and ASTM D7264 standard samples for SBSS and Flexural strength test respectively. Test results show an increase in ILSS by 207.58% and Flexural strength by 63.82% respectively of samples with notches at 3 wt.% doping of MWCNTs. From the FESEM images the failure initiation and propagation could be observed for the different tests which are investigated in this experiment.

An Experimental Analysis on Flexural Strength of Concrete Beams using Silica Fumes & Fly ash including Coir Fibre with Admixture

An Experimental Analysis on Flexural Strength of Concrete Beams using Silica Fumes & Fly ash including Coir Fibre with Admixture

Effects of floor slabs on the flexural strength of beams in reinforced concrete buildings

The effects of floor slabs on the flexural strength of beams in reinforced concrete buildings under seismic action were verified through tests of frame assembly specimens. A series of experimental and analytical investigations were conducted from 2010 to 2014 in order to further validate the current design practices in Japan. Loading methods in the past beam component tests were reviewed with probable effects of floor slabs. A special loading set-up was used for the frame assembly specimens consisting of four columns and four beams with lengths of one span and two half spans in two directions. The four columns were loaded laterally and independently at mid-height of the upper storey and supported at mid-height of the lower storey with pin-fixed and pin-roller so that axial elongation of the beams and slab would not be constrained by the lateral forces. It has been found from these new loading tests that the tensile stresses in the floor slab reinforcing bars are generally uniform at the beam critical sections and up to the full slab width for the flexural strength when the slab is subjected to tension bending around one percent storey drift, which is much wider than assumed in the current design evaluation.

EFFECTS ON STRENGTH OF CONCRETE BY PARTIAL REPLACEMENT OF CEMENT WITH FLY ASH AND PAPER SLUDGE ASH

In this dissertation study on utilizations of waste paper sludge ash to produce on economic concrete by blending various ratios of cement with waste paper sludge ash along with fly ash there by and to reduce disposal and related pollution problems. The innovative use of waste paper sludge ash in concrete as a supplementary cementitious material along with fly ash explored. The main aim of this study is to evaluate the effects on the proportion of concrete with paper sludge ashafly ash (as partial replacement of cement) in concrete when it is mixed in cement concrete for workability, and strength of concrete using OPC (43 grade). Paper sludge ash is supplementary cementitious material and fly ash is pozzolanic materials that can be utilized to produce highly durable concrete composites. In this study waste paper sludge ash has been used to partially replace OPC which varies from 0% to 15% at interval of 5% by total weight of OPC and similarly cement has been replaced by fly ash which varies 0% to 15% at interval of 5% by total weight of cement in the equal proportion and prepared for M25aM30 grade of concrete. This study investigates the performance of concrete under the influence of paper sludge ash and fly ash in terms of slump and compressive strength at 7 days and 28 days, flexural strength of beam at 28 days and splitting tensile strength of Cylinder at 28 days respectively. The required of specimens of cubes, cylinders and beams were casted for testing to study the influence of paper sludge ashafly ash on concrete. These Concrete specimens were deep cured in water under normal atmospheric conditions in laboratory On the basis of result that paper sludge ash and fly ash mix concrete was found to increase in all strength (Compressive, FlexuralaSplitting Tensile strength) of various mix of concrete at all age when compared to normal concrete. Its use should be promoted for better performance as well as for environmental sustainability. Test results indicate that use of waste paper sludge ash in concrete has improved the performance of concrete.

Improving Mechanical Properties of Carbon/Epoxy Composite by Incorporating Functionalized Electrospun Polyacrylonitrile Nanofibers

Electrospun functionalized polyacrylonitrile grafted glycidyl methacrylate (PAN‐g‐GMA) nanofibers are incorporated between the plies of a conventional carbon fiber/epoxy composite to improve the composite's mechanical performance. Glycidyl methacrylate (GMA) is successfully grafted onto polyacrylonitrile (PAN) polymer powder via a free radical mechanism. Characterization of the electrospun PAN and PAN‐g‐GMA nanofibers indicates that the grafting of GMA does not significantly alter the tensile properties of the PAN nanofibers but results in an increase in the diameter of nanofibers. Statistical analysis of the mechanical characterization studies on PAN‐carbon/epoxy hybrid composites conclusively shows that the composite reinforced with functionalized PAN nanofibers has greater mechanical properties than that of both the neat PAN nanofiber enriched hybrid composite and control composite (without nanofibers). The improved performance is attributed to the grafted glycidyl groups on PAN, leading to stronger interactions between the nanofibers and the epoxy matrix. PAN‐g‐GMA nanofiber reinforced composite outperforms their neat PAN counterparts in tensile strength, short beam shear strength, flexural strength, and Izod impact energy absorption by 8%, 9%, 6%, and 8%, respectively. Compared to the control composite, the improvements resulting from the PAN‐g‐GMA nanofiber incorporation are even more pronounced at 28%, 41%, 32%, and 21% in the corresponding tests, respectively. image

The effect of polymer coated pumice to the stiffness and flexural strength of reinforce concrete beam

Pumice has been proven as substitution material aggregate in lightweight aggregate concrete (LWAC). However due to its characteristic, pumice has the disadvantages of its excessive water absorption during preparation of concrete mixture which may reduce concrete strength. Therefore in order to eliminate this additional water absorption, this study investigate the effect of coated pumice in concrete mixture to the beam flexural strength and stiffness. This study performed flexural strength test on three types of sample: 1) normal reinforce concrete beam, 2) reinforce concrete beam with uncoated pumice and 3) reinforce concrete beam with coated pumice. The result showed that the lightest weight concrete occurred on the coated pumice specimen, with the reduction of water absorption was 4% compared to the uncoated pumice specimen. The stiffness of the reinforce beam with coated pumice was lower compared to the uncoated ones, this was due to the reduction of adhesion action between cement and aggregates. However, the use of coated pumice increased the flexural strength compare to the uncoated ones with 2.58%.

Evaluation of flexural strength prediction of reinforced concrete beams with steel fibres

This paper presents experimental programme to investigate the effects of steel fibres on flexural strength of steel fibre-reinforced concrete (SFRC) beams and proposes a prediction model to evaluate flexural strength of beams which is their main contribution to literature. Four point bending test was carried out on the 11 SFRC beams which are 6 normal-strength SFRC beams and 5 high-strength SFRC beams. The variables studied in the investigation were steel fibre volume fractions (0, 0.75 and 1.50%), flexural reinforcement ratios (1.0 and 2.0%), and concrete compressive strengths (28 and 56 MPa). The test results confirmed that ultimate flexural strength increased with increasing fibre volume contents. The constitutive model for SFRC was proposed, which incorporated strength of fibre-reinforced concrete and strain-hardening of tensile reinforcement. Predictions of moment–curvature relationship based on the model matched well with the experimental data. The results of previously reported tests were combined with the results of new tests to document observed flexural failures of 129 SFRC beams. A simplified, empirical design equation to determine the flexural strength of SFRC beam was proposed and compared with existing equations. The analysis indicated that the proposed equation provided the most accurate estimates of flexural strength.

Experimental Study on Full-Scale Beams Made by Reinforced Alkali Activated Concrete Undergoing Flexure.

Alkali Activated Concrete (AAC) is an alternative kind of concrete that uses fly ash as a total replacement of Portland cement. Fly ash combined with alkaline solution and cured at high temperature reacts to form a binder. Four point bending tests on two full scale beams made with AAC are described in this paper. Companion small material specimens were also casted with the aim of properly characterizing this new tailored material. The beam’s length was 5000 mm and the cross section was 200 mm × 300 mm. The AAC consisted of fly ash, water, sand 0–4 mm and coarse aggregate 6–10 mm; and the alkaline solution consisted of sodium hydroxide mixed with sodium silicate. No cement was utilized. The maximum aggregate size was 10 mm; fly ash was type F, containing a maximum calcium content of 2%. After a rest period of two days, the beam was cured at 60 °C for 24 h. Data collected and critically discussed included beam deflection, crack patterns, compressive and flexural strength and elastic modulus. Results show how AAC behavior is comparable with Ordinary Portland Cement (OPC) based materials. Nonlinear numerical analyses are finally reported, promoting a better understanding of the structural response.

Bond Degradation–Induced Incompatible Strain between Steel Bars and Concrete in Corroded RC Beams

AbstractBond degradation–induced incompatible strain between corroded steel bars and concrete is investigated in this paper. A compatibility coefficient and a nonlinear analysis method are introduced to quantify the incompatible strain. The effect of corrosion losses, loading levels, loading conditions, and the span-to-depth ratio on the incompatible strain are investigated in detail. The incompatible strain effects on the beam flexural strength have been clarified. A simplified formula is then proposed to calculate the ultimate compatibility coefficient. Further, an attempt has also been made to incorporate this coefficient into the flexural strength prediction for corroded RC beams. Results show that the incompatible strain depends on the loading levels and corrosion losses. Corrosion has a negligible effect on the incompatible strain until the corrosion loss exceeds a critical value. For severely corroded beams, the incompatible strain increases rapidly as the loading level increases and saturates to a...

Subassemblage Cyclic Loading Tests of Buckling-Restrained Braced RC Frames with Unconstrained Gusset Connections

AbstractAn unconstrained gusset connection for buckling restrained braces in reinforced concrete frame structures is proposed and tested as an effort to mitigate the complicated and usually harmful interactions between the steel gusset plate and the adjoining reinforced concrete column. Local damage control incorporating the rearrangement of beam flexural strength is also proposed to enhance the reliability of the gusset connection by moving the potential plastic hinge of the beam away from the connection region. Two different connecting methods, one with posttensioned steel rods and the other embedded stud groups, were considered. The results of the cyclic loading tests on reinforced concrete (RC) beam-gusset connection subassemblies confirmed that both connecting methods are available as long as the local damage control is implemented, which is not only helpful in eliminating the unfavorable deformation loss at the connection, but more importantly, can prevent the buckling restrained braces (BRBs) from ...

폭발에 의한 국부손상이 철근콘크리트 보의 휨강도에 미치는 영향과 전단 철근 배근에 따른 폭발저항 성능

폭발에 의한 국부손상이 철근콘크리트 보의 휨강도에 미치는 영향과 전단 철근 배근에 따른 폭발저항 성능

Effect of Intermediate Crack Debonding on the Flexural Strength of CFRP-Strengthened RC Beams

The flexural strength of reinforced concrete (RC) beams strengthened with a carbon-fiber-reinforced polymer plate, which fails by intermediate crack debonding, is evaluated. To consider the effect of debonding at the interface between the concrete and the CFRP plate, due to a flexural crack at the midspan, on the flexural strength of the beams, a strength reduction factor is proposed. This factor is derived from the results of flexural tests by using the model of effective strains and is defined as the ratio of the debonding strain to the ultimate strain of the CFRP plate. The validity, accuracy, and efficiency of the factor is verified by comparing analytical results with experimental data. The results of this study revealed that the strength reduction factor proposed can be used to efficiently assess the flexural strength of CFRP-strengthened RC beams with intermediate crack debonding.

An Investigation on Engineering Properties of Composite Beam

There is several agriculture waste materials have continuously been producing. The oil palm shell has been used to produce Oil Palm Shell Concrete (OPSC). And by use of 1% Kenaf-Oil Palm Shell mixture, a natural composite concrete (OPS-kenaf concrete) has been made. The time to failure, stroke and flexural strength of concrete beams have been studied. The concrete cubes have also been tested to identify time to failure and compressive strength of proposed concretes. The results have been indicated that 1% kenaf-OPS mixture enhances flexural strength of beam. And also the stroke and time to failure have not considerably been changed. The significant effect has not been observed on morphology of crack. The compressive strength of (OPS-1% kenaf mixture) has been improved. This new proposed composite concrete beam has acceptable effect on minimizing environment pollution.

Flexural Behavior of Beams Incorporating GGBS as Partial Replacement of Fine Aggregate in Concrete

Ground-granulated blast-furnace slag (GGBS) is obtained as waste product from the Iron industries, Ground-granulated blast-furnace slag (GGBS or GGBFS) is obtained by quenching molten iron slag (a by-product of iron and steel-making) from a blast furnace in water or steam, to produce a glassy, granular product that is then dried and ground into a fine powder. Investigations were carried out to explore the possibility of using GGBS as a replacement of sand in concrete mixtures. This paper presents the results of study undertaken to investigate the feasibility of using GGBS as fine aggregate in concrete. The effects of replacing fine aggregates by GGBS on the compressive strength of cubes, split tensile strength of cylinders and flexural strength of beams are evaluated in this study. Five test groups were constituted with the replacement percentages of 0%, 20%, 30%, 40%, and 50% .The results showed the effect of GGBS on RCC concrete elements has a considerable amount of increase in the compressive, split tensile and flexural strength characteristics. Leaching studies revealed that GGBS does not leach heavy metals like Pb, Zn, Cr, Ni, Mo etc and also indicates that the leaching of heavy metals was well below the toxicity limits even under aggressive conditions.