Structural Imposed Load Analysis of Isotropic Rectangular Plate Carrying a Uniformly Distributed Load Using Refined Shear Plate Theory

This presents the static flexural analysis of a three edge simply supported, one support free (SSFS) rectangular plate under uniformly distributed load using a refined shear deformation plate theory. The shear deformation profile used, is in the form of third order. The governing equations were determined by the method of energy variational calculus, to obtain the deflection and shear deformation along the direction of x and y axis. From the formulated expression, the formulars for determination of the critical lateral imposed load of the plate before deflection reaches the specified maximum specified limit and its corresponding critical lateral imposed load before plate reaches an elastic yield stress is established. The study showed that the critical lateral imposed load decreased as the plates span increases, the critical lateral imposed load increased as the plate thickness increases, as the specified thickness of the plate increased, the value of critical lateral imposed load increased and increase in the value of the allowable deflection value required for the analysis of the plate reduced the chances of failure of a structural member. This approach overcomes the challenges of the conventional practice in the structural analysis and design which involves checking of deflection and shear after design; the process which is proved unreliable and time consuming. It is concluded that the values of critical lateral load obtained by this theory achieve accepted transverse shear stress to the depth of the plate variation in predicting the flexural characteristics for an isotropic rectangular SSFS plate. Numerical comparison was conducted to verify and demonstrate the efficiency of the present theory, and they agreed with previous studies. This proved that the present theory is reliable for the analysis of a rectangular plate. Keywords— Allowable deflection, critical imposed load, energy method, plate theories, shear deformation, SSFS rectangular plate

Effects of additional load at different heights on gait initiation: A statistical parametric mapping of center of pressure and center of mass behavior

The purpose of this study was to investigate the effects of different vertical positions of an asymmetrical load on the anticipatory postural adjustments phase of gait initiation. Sixty-eight college students (32 males, 36 females; age: 23.65 ± 3.21 years old; weight: 69.98 ± 8.15 kg; height: 1.74 ± 0.08 m) were enrolled in the study. Ground reaction forces and moments were collected using two force platforms. The participants completed three trials under each of the following random conditions: no-load (NL), waist uniformly distributed load (WUD), shoulder uniformly distributed load (SUD), waist stance foot load (WST), shoulder stance foot load (SST), waist swing foot load (WSW), and shoulder swing foot load (SSW). The paired Hotelling’s T-square test was used to compare the experimental conditions. The center of pressure (COP) time series were significantly different for the SUD vs. NL, SST vs. NL, WST vs. NL, and WSW vs. NL comparisons. Significant differences in COP time series were observed for all comparisons between waist vs. shoulder conditions. Overall, these differences were greater when the load was positioned at the shoulders. For the center of mass (COM) time series, significant differences were found for the WUD vs. NL and WSW vs. NL conditions. However, no differences were observed with the load positioned at the shoulders. In conclusion, only asymmetrical loading at the waist produced significant differences, and the higher the extra load, the greater the effects on COP behavior. By contrast, only minor changes were observed in COM behavior, suggesting that the changes in COP (the controller) behavior are adjustments to maintain the COM (controlled object) unaltered.

Structural Behavior of BubbleDeck Slab under Uniformly Distributed Load

In structural construction fields, reducing the overall self-weight of the structure is considered a primary objective and substantial challenge in the civil engineering field, particularly in earthquake-affected buildings and tall buildings. Different techniques were implemented to attain this goal; one of them is setting voids in a specific position through the structure, just like a voided slab or BubbleDeck slab. The main objective of this research is to study the structural behavior of BubbleDeck reinforced concrete slabs under the effect of static uniformly distributed load. The experimental program involved testing five fixed-end supported two-way solid and BubbleDeck slabs of dimensions 2500×2500×200 mm. The considered parameters included the bubble's diameter 100 and 120 mm and the concrete volume reduction 15 and 18 %. The other parameters, which are concrete compressive strength and detail of the steel reinforcement, were identical for all the tested specimens to be for the compressive strength and (∅ 10 @164 mm) for the steel reinforcement. The outcomes indicated that the ultimate load capacity for a BubbleDeck slab decreased by 15.93 and 11.5 % compared to the solid slab in case of concrete volume reductions 18 and 15 %, respectively. On the other hand, an advanced behavior, including the ultimate deflection, the absorbed energy, and the ductility factor, was achieved; the increments in these parameters were 39, 5.3, and 14.94 %, respectively. Doi: 10.28991/cej-2021-03091655 Full Text: PDF

Simulation and Experimental Substantiation of Beam Deflection under Guided End Conditions

This paper studies the nonlinear deflection characteristics of a rectangular cross sectional beam with guided support conditions. In this study two different end conditions namely guided – guided and guided – simply supported have been examined. Beams made with two dissimilar materials for instance, aluminum and steel have been considered for this study. Different loading conditions namely point load and the amalgamation of uniformly distributed load and point load have been taken into account in this study. The nonlinear response of a beam under static loading condition is influenced by various parameters like sectional properties of the beam, material, loading and boundary conditions etc. A separate loading fixture was fabricated using steel to apply the load (Point load and uniformly distributed load). The loading fixture was validated by performing an experimental measurement of the deflection under various loading conditions on a simply supported beam. The corresponding theoretical displacement values were calculated using the findings in literature and compared with test results .Both the results were found matching with each other with an average variation of just 10%. Based on this validation lesson, the loading fixture was incorporated in the actual study. Displacement values from the nonlinear static analysis were predicted using Finite Element Method and correlation was made with the experimental values for the actual beam setup. Close correlation among the numerical and physical test results was achieved and the maximum error was 8%.

Effects of additional load at different heights on gait initiation: a statistical parametric mapping of center of pressure and center of mass behavior

The purpose of this study was to investigate the effects of different vertical positions of an asymmetrical load on the anticipatory postural adjustments phase of gait initiation. Sixty-eight college students (32 males, 36 females; age: 23.65 ± 3.21 years old; weight: 69.98 ± 8.15 kg; height: 1.74 ± 0.08 m) were enrolled in the study. Ground reaction forces and moments were collected using two force platforms. The participants completed three trials under each of the following random conditions: no-load (NL), waist uniformly distributed load (WUD), shoulder uniformly distributed load (SUD), waist stance foot load (WST), shoulder stance foot load (SST), waist swing foot load (WSW), and shoulder swing foot load (SSW). The paired Hotelling’s T-square test was used to compare the experimental conditions. The center of pressure (COP) time series were significantly different for the SUD vs. NL, SST vs. NL, WST vs. NL, and WSW vs. NL comparisons. Significant differences in COP time series were observed for all comparisons between waist vs. shoulder conditions. Overall, these differences were greater when the load was positioned at the shoulders. For the center of mass (COM) time series, significant differences were found for the WUD vs. NL and WSW vs. NL conditions. However, no differences were observed with the load positioned at the shoulders. In conclusion, only asymmetrical loading at the waist produced significant differences, and the higher the extra load, the greater the effects on COP behavior. By contrast, only minor changes were observed in COM behavior, suggesting that the changes in COP (the controller) behavior are adjustments to maintain the COM (controlled object) unaltered.