Flexural rigidity

About: Flexural rigidity is a research topic. Over the lifetime, 3829 publications have been published within this topic receiving 56780 citations.

Flexural strengthening of reinforced concrete beams using bonded polymer composite plates.

Abstract: The in situ rehabilitation or upgrading of reinforced concrete (RC) members using bonded steel plates has been proven in the field to be an effective, convenient and economic method of improving structural performance. However, disadvantages inherent in the use of steel have stimulated research into the possibility of using fibre- reinforced polymer (FRP) materials in its place, providing a non-corrosive, more versatile strengthening system. The aim of this investigation was to provide a detailed study of the flexural strengthening of RC beams using FRP plates. Experimental testing of 1.0 m length specimens was used to illustrate the feasibility and general characteristics of external FRP strengthening. A parametric study was also carried out to evaluate the influence of basic geometric and material parameters on overall performance. Larger-scale 2.3 m length beams were used to confirm the general behaviour observed in the 1.0 m tests. The structural effects of pre-tensioning the FRP plate prior to bonding to the beam were also examined. Although moderate increases in flexural rigidity and strength over a non-prestressed member were attained by the use of this technique, the greatest influence observed was restraint on the initiation and development of cracking. The performance of the component materials and overall strengthened system under sustained load application and adverse environmental conditions was considered experimentally. The results, although somewhat limited, suggest that environmental deterioration of the mechanical properties of bulk adhesive specimens does not necessarily imply a degradation of the bond performance in situ or a reduction in the long-term structural behaviour of the strengthened member. Similarly, the viscoelastic nature exhibited by the epoxy adhesive when tested in isolation did not appear to affect the time-dependent behaviour of the strengthened member; the addition of the externally bonded FRP plate appeared to have only beneficial influences on long-term behaviour. The effectiveness of theoretical methods of predicting FRP strengthened beam response to load application was finally assessed. A simple, iterative analytical technique was generally found to provide good correlation with the global behaviour determined experimentally. Theories proposed to account for the occurrence of premature failure of steel plated beams were evaluated; these appear to be unsuitable for FRP strengthened members. Use of the finite element (FE) method for predicting flexural response was also investigated. In this case, agreement with behaviour observed in testing was found to be poor. This was attributed to the representation of material response incorporated in the FE package.

Elastic design charts of stiffened coupled structural walls

Abstract: Design charts are presented for the design of a stiffened coupled structural wall with a strong beam located somewhere along the building height. The analysis is based on a continuous medium approach with the deflection at the top. The couple due to the axial force in the walls and the shear force in the laminae are presented in the form of graphs. The variations of the couple due to the axial force in the walls and the laminar shear along the structural height are also presented to permit the curtailment of reinforcements where appropriate for achieving economy. The results are given in terms of two dimensionless structural parameters: one is the relative flexural rigidity of the strong beam, and the other is a measure of the effectiveness of the lintel beams. The application of the design charts is illustrated by determining the deflections and the internal forces of a typical 20-story building.

Calculation of membrane bending rigidity using field-theoretic umbrella sampling.

Abstract: The free-energy change of membrane shape transformations can be small, e.g., as in the case of membrane bending. Therefore, the calculation of the free-energy difference between different membrane morphologies is a challenge. Here, we discuss a computational method — field-theoretic umbrella sampling — to compute the local chemical potential of a non-equilibrium configuration and illustrate how one can apply it to study free-energy changes of membrane transformations using simulations. Specifically, the chemical potential profile of the bent membrane and the bending rigidity of membrane are calculated for a soft, coarse-grained amphiphile model and the MARTINI model of a dioleoylphosphatidylcholine (DOPC) membrane.

Behavior of Wide Shallow RC Beams Strengthened with CFRP Reinforcement

Abstract: One-way reinforced concrete joist floors with wide shallow beams (WSBs) are used widely in building construction throughout the Middle East. The short- and long-term behavior of WSBs externally strengthened with carbon fiber-reinforced polymer (CFRP) reinforcement was studied on isolated beams and as part of full-scale building. This paper presents the results of the experimental investigation on the flexural performance of isolated WSBs externally strengthened with CFRP reinforcement. A total of six full-scale beams were constructed and tested to failure. The test variables were the amount, type, configuration, and the elastic modulus of CFRP reinforcement. The test results were presented in terms of deflections, ultimate capacities and modes of failure, crack width development, and strains in reinforcement and concrete. The test results showed significant improvement in the flexural performance of the strengthened beams with respect to flexural capacity, flexural stiffness, and crack width. All but one of the strengthened beams failed because of the debonding of CFRP reinforcement; however, the load carrying capacity of WSBs were more than that predicted by relevant design guidelines.

Flexural stiffness of steel-concrete composite beam under positive moment

Abstract: This paper investigates the flexural stiffness of simply supported steel-concrete composite I-beams under positive bending moment through combined experimental, numerical, and different standard methods. 14 composite beams are tested for experimental study and parameters including shear connection degree, transverse and longitudinal reinforcement ratios, loading way are also investigated. ABAQUS is employed to establish finite element (FE) models to simulate the flexural behavior of composite beams. The influences of a few key parameters, such as the shear connection degree, stud arrangement, stud diameter, beam length, loading way, on the flexural stiffness is also studied by parametric study. In addition, three widely used standard methods including GB, AISC, and British standards are used to estimate the flexural stiffness of the composite beams. The results are compared with the experimental and numerical results. The findings have provided comprehensive understanding of the flexural stiffness and the modelling of the composite beams. The results also indicate that GB 50017-2003 could provide better results in comparison to the other standards.