Flexural behavior of two-span continuous prestressed concrete girders with highly eccentric external tendors

[Abstract]: It is generally known that the flexural strength of beams prestressed with external tendons is comparatively lower than that of members with internal bonded tendons. One possible method of enhancing the flexural strength of such beams is to place the tendons at high eccentricity. To obtain an insight into the flexural behavior of beams with highly eccentric tendons, an experimental investigation is conducted on single-span and two-span continuous beams. The test variables include external tendon profile, loading pattern on each span, casting method, and confinement reinforcements. It is found that continuous girders with linearly transformed tendon profiles exhibit the same flexural behavior irrespective of tendon layout. The presence of confinement reinforcement enhances the ductility behavior but does not increase the ultimate flexural strength. The degree of moment redistribution is affected by the tendon layout and the loading pattern on each span. The results of the experimental investigation are discussed in this paper

Mechanical behavior of irregular fibers part III : the flexural buckling behavior

Fiber buckling behavior is associated with fabric-evoked prickle, which affects clothing comfort and aesthetics. In this paper, the flexural buckling behavior of irregular or nonuniform fibers is studied using the finite element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude, frequency, and initial phase. The critical buckling loads of the simulated fibers are then calculated from the FE model. The results indicate that increasing the level of irregularity will decrease the critical buckling load of fibers, but the effect of the frequency and initial phase of irregularity on fiber buckling behavior is complicated and is affected by fiber diameter and effective length

Scattering theory and cancellation of gravity-flexural waves of floating plates

We combine theories of scattering for linearized water waves and flexural waves in thin plates to characterize and achieve control of water wave scattering using floating plates. This requires manipulating a sixth-order partial differential equation with appropriate boundary conditions of the velocity potential. Making use of multipole expansions, we reduce the scattering problem to a linear algebraic system. The response of a floating plate in the quasistatic limit simplifies, considering a distinct behavior for water and flexural waves. Unlike similar studies in electromagnetics and acoustics, scattering of gravity-flexural waves is dominated by the zeroth-order multipole term and this results in non-vanishing scattering cross-section also in the zero-frequency limit. Potential applications lie in floating structures manipulating ocean waves.Comment: 19 pages, 4 figure

Measurement of the time-temperature dependent dynamic mechanical properties of boron/aluminum composites

A flexural vibration test and associated equipment were developed to accurately measure the low strain dynamic modulus and damping of composite materials from -200 C to over 500 C. The basic test method involves the forced vibration of composite bars at their resonant free-free flexural modes in a high vacuum cryostat furnace. The accuracy of these expressions and the flexural test was verified by dynamic moduli and damping capacity measurements on 50 fiber volume percent boron/aluminum (B/Al) composites vibrating near 2000 Hz. The phase results were summarized to permit predictions of the B/Al dynamic behavior as a function of frequency, temperature, and fiber volume fraction

Flexural–torsional behavior of thin-walled composite space frames

A general analytical model based on the first-order shear deformable beam theory applicable to thin-walled composite space frames with arbitrary lay-ups under external loads is presented. This model accounts for all the structural coupling coming from the material anisotropy. The seven governing equations are derived from the principle of the stationary value of total potential energy. A displacement-based one-dimensional 14 degree-of-freedom space beam model which includes the effects of shear deformation, warping is developed to solve the problem. Numerical results are obtained to investigate the effects of fiber orientation on flexural–torsional responses of thin-walled composite space frame under vertical load

Flexural analysis of concrete beams longitudinally reinforced with GFRP bars using discrete element model

This paper presents experimental and analytical study related to the flexural behavior of concrete beams longitudinally reinforced with GFRP bars. The specimens consist of simply supported reinforced concrete beams with two point load. Totally 16 concrete beams includes 8 beams reinforced with steel and 8 beams reinforced with GFRP bars were tested to failure. Flexural capacity of the beam was observed experimentally and analytically. A computer program of cross sectional analysis using discrete element model was developed in this study to determine the flexural capacity of the beams. In addition, available stress-strain model proposed by the other researchers was used in order to simulate the behavior of material in calculation process. Finally, the flexural capacity obtained from analytical calculation was compared to that obtained from the test in term of moment-curvature curves and load deflection curves. The results show that beam reinforced with GFRP experienced larger ultimate load and larger deflection at same load level compared to beam reinforced with steel. Keyword: Reinforced concrete beams, Glass Fiber Reinforced Polymer (GFRP), Flexural capacity

On the path to a new generation of cement-based composites through the use of lignocellulosic micro/nanofibers

Due to its high biocompatibility, bio-degradability, and low cost, cellulose finds application in disparate areas of research. Here we focus our attention on the potential applications of cellulose nanofiber in cement-basedmaterials for the building sector. We first describe the chemical/morphological composition of cellulose fibers, their process and treatment, the characterization of cement-based composites, and their flexural strengthPeer ReviewedPostprint (published version

Mechanical properties of epoxy/coconut shell filler particle composites

This paper presents the tensile and flexural properties of composites made from coconut shell filler particles and epoxy resin. The tensile and flexural tests of composites based on coconut shell filler particles at three different filler contents viz. 5%, 10%, and 15%, were carried out using universal tensile testing machine according to ASTM D 3039/D 3039 M-95a and ASTM D790-90 respectively and their results were presented. Experimental results showed that tensile and flexural properties of the composites increased with the increase of the filler particle content. The composite materials demonstrate somewhat linear behavior and sharp fracture for tensile and slight non-linear behavior and sharp fracture for flexural testing. The relation between stress and percentage of filler for tensile and flexural tests were found to be linear with correlation factors of 0.9929 and 0.9973 respectively. Concerning the relation between the modulus and percentage of filler for tensile and flexural tests, it was found to be a quadratic relation with the same correlation factor approximated to 1. The same behavior was observed for the strain versus percentage of filler for tensile and flexural tests, with the same correlation factor