Ultimate and Deflection Performance of Concrete Beams Strengthened in Flexure with Basalt-Textile-Reinforced Polymer Mortar.

This paper presents an investigation into the ultimate and serviceability behavior of concrete beams strengthened in flexure with basalt-textile-reinforced polymer mortar (BTRM). The bond performance at the interface between the BTRM and concrete was studied by performing single shear tests, and the effectiveness of using an adhesion promoter and impregnated resin for bond enhancement was explored. The results suggested that using an adhesion promoter and impregnated resin can improve the interfacial stress transfer and ensure the tensile failure of the basalt textile in BTRM. Afterward, four-point bending tests were conducted to study the flexural performance of strengthened beams. It was found that the flexural strength of strengthened beams increased with the amount of textile, and the strength increase was more prominent for the strengthened beams with end anchorages. The increase in the failure force was up to 37% for the beam strengthened with five layers of the textile and an end anchorage. The calculated flexural strength exhibited a percentage error of no more than 7% compared to the test results. In addition, the Bischoff-I Equation can closely estimate the effective moment of inertia and provide an accurate prediction of deflection for strengthened beams.

Experimental Study on the Durability of Steel Anchors for Prestressed CFRP Laminates under Accelerated Galvanostatic Corrosion.

The novelty of the present study is to address the durability of corroded anchors for prestressing CFRP laminates. Two types of steel anchors, clamp anchors and wedge anchors, were used to prestress CFRP laminates and then subjected to steel corrosion through a galvanostatic acceleration approach, which was followed by tensile tests. Compared to clamp anchors, wedge anchors showed a superior durability performance in terms of their prestress retention, anchor efficiency, and resistance to the slippage of the CFRP laminate. After accelerated corrosion for 144 h, the clamp anchor exhibited a prestress retention of 79.1% and an anchorage efficiency of 55%, and the percentages became 9.0% and 100% for the wedge anchor. The slippage rates of the clamp anchor and the wedge anchor were 0.036 mm/kN and 0.026 mm/kN, respectively. Therefore, the wedge anchor, which exhibited higher prestress tension and anchorage efficiency, performed better than the clamp anchor. The present work provides an apparatus for exploring the corrosion-induced durability of steel anchors and experimental evidence that helps refine the provision in the guidelines for addressing anchor durability.

Double-Level Energy Absorption of 3D Printed TPMS Cellular Structures via Wall Thickness Gradient Design.

This paper investigates the deformation mechanism and energy absorption behaviour of 316 L triply periodic minimal surface (TPMS) structures with uniform and graded wall thicknesses fabricated by the selective laser melting technique. The uniform P-surface TPMS structure presents a single-level stress plateau for energy absorption and a localized diagonal shear cell failure. A graded strategy was employed to break such localized geometrical deformation to improve the overall energy absorption and to provide a double-level function. Two segments with different wall thicknesses separated by a barrier layer were designed along the compression direction while keeping the same relative density as the uniform structure. The results show that the crushing of the cells of the graded P-surface TPMS structure occurs first within the thin segment and then propagates to the thick segment. The stress-strain response shows apparent double stress plateaus. The stress level and length of each plateau can be adjusted by changing the wall thickness and position of the barrier layer between the two segments. The total energy absorption of the gradient TPMS structure was also found slightly higher than that of the uniform TPMS counterparts. The gradient design of TPMS structures may find applications where the energy absorption requires a double-level feature or a warning function.

Enhanced active contraction of the transversus abdominis during walking / Aumento de la contracción activa del músculo transverso del abdomen durante la caminata / Aumento da contração ativa do músculo transverso do abdome durante a caminhada

ABSTRACT Introduction: We applied three-dimensional gait analysis to assess the effects of enhanced active contraction of the transversus abdominis (EACTA) during walking. We sought to evaluate the effect of EACTA during walking in order to improve walking quality. Methods: Thirty college students were recruited and trained to perform EACTA during walking. We examined gait parameters under different conditions, including EACTA and habitual ACTA (natural walking with mild contraction of the feedforward mechanism of ACTA, HACTA) during walking using three-dimensional gait analysis. We compared differences in gait parameters under the two walking conditions using SPSS 16.0 statistical software. Results: The following gait parameters were significantly lower under EACTA conditions than under HACTA conditions (P < 0.05): stance phase, 59.151% ± 1.903% vs. 59.825% ± 1.495%; stride time, 1.104 s ± 0.080 s vs. 1.134 s ± 0.073 s:; stance time, 0.656 s ± 0.057 s vs. 0.678 s ± 0.053 s; and swing time, 0.447 s ± 0.028 s vs. 0.454 s ± 0.031 s, respectively. Gait parameters single support phase and mean velocity were significantly higher for EACTA than for HACTA conditions (both P < 0.05). Conclusions: Overall, the results revealed that EACTA during walking can improve gait. This method is simple, and EACTA training during walking to improve gait quality in daily life could provide a positive basis for people to strengthen the transverse abdominal muscle. Level of evidence III; Retrospective comparative study .

RESUMEN Introducción: Aplicamos el análisis tridimensional de la marcha para evaluar los efectos del aumento de la contracción activa del músculo transverso del abdomen (EACTA) durante la caminata. Buscamos evaluar el efecto del EACTA durante la caminata para mejorar su calidad. Métodos: Treinta estudiantes universitarios fueron reclutados y entrenados para realizar el EACTA durante la caminata. Examinamos los parámetros de la marcha en diferentes condiciones, incluyendo EACTA y ACTA habitual (caminata natural con leve contracción del mecanismo de feedforward del ACTA, HACTA) durante la caminata usando análisis tridimensional de la marcha. Comparamos las diferencias en los parámetros de la marcha en las dos condiciones de caminata en el software estadístico SPSS 16.0. Resultados: Los siguientes parámetros de marcha fueron significativamente más bajos en la condición EACTA que en condiciones HACTA (P <0,05): fase de apoyo 59,151 ± 1,903% vs 59,825 ± 1,495%, tiempo de zancada 1,104 s ± 0,080 s vs 1,134 s ± 0,073 s, tiempo de apoyo 0,656 s ± 0,057 s vs 0,678 s ± 0,053 s y tiempo de balance 0,447 s ± 0,028 s vs 0,454 s ± 0,031 s, respectivamente. Los parámetros de la marcha, fase de apoyo simple y velocidad promedio fueron significativamente mayores en el EACTA que en las condiciones HACTA (ambos P <0,05). Conclusiones: En general, los resultados revelaron que el EACTA durante la caminata puede mejorar la marcha. Este método es simple, y el entrenamiento del EACTA durante la caminata para mejorar la calidad de la marcha en la vida diaria puede ser una base positiva para el fortalecimiento del músculo transverso del abdomen. Nivel de evidencia III; Estudio retrospectivo comparativo .

RESUMO Introdução: Aplicamos a análise tridimensional da marcha para avaliar os efeitos do aumento da contração ativa do músculo transverso do abdome (EACTA) durante a caminhada. Procuramos avaliar o efeito do EACTA durante a caminhada para melhorar sua qualidade. Métodos: Trinta estudantes universitários foram recrutados e treinados para realizar o EACTA durante a caminhada. Examinamos os parâmetros da marcha em diferentes condições, incluindo EACTA e ACTA habitual (caminhada natural com leve contração do mecanismo de feedforward do ACTA, HACTA) durante a caminhada usando análise tridimensional da marcha. Comparamos as diferenças nos parâmetros da marcha nas duas condições de caminhada no software estatístico SPSS 16.0. Resultados: Os seguintes parâmetros da marcha foram significativamente mais baixos na condição EACTA do que em condições HACTA (P < 0,05): fase de apoio 59,151 ± 1,903% vs. 59,825 ± 1,495%, tempo de passada 1,104 s ± 0,080 s vs. 1,134 s ± 0,073 s, tempo de apoio 0,656 s ± 0,057 s vs. 0,678 s ± 0,053 s e tempo de balanço 0,447 s ± 0,028 s vs. 0,454 s ± 0,031 s, respectivamente. Os parâmetros da marcha fase de apoio simples e velocidade média foram significativamente maiores no EACTA do que nas condições HACTA (ambos P < 0,05). Conclusões: No geral, os resultados revelaram que o EACTA durante a caminhada pode melhorar a marcha. Esse método é simples, e o treinamento do EACTA durante a caminhada para melhorar a qualidade da marcha na vida diária pode ser uma base positiva para o fortalecimento do músculo transverso do abdome. Nível de evidência III; Estudo retrospectivo comparativo .

Grain Size Effect of the γ Phase Precipitation on Martensitic Transformation and Mechanical Properties of Ni-Mn-Sn-Fe Heusler Alloys.

Isothermal annealing of a eutectic dual phase Ni-Mn-Sn-Fe alloy was carried out to encourage grain growth and investigate the effects of grain size of the γ phase on the martensitic transformation behaviour and mechanical properties of the alloy. It is found that with the increase of the annealing time, the grain size and volume fraction of the γ phase both increased with the annealing time predominantly by the inter-diffusion of Fe and Sn elements between the γ phase and the Heusler matrix. The isothermal anneals resulted in the decrease of the e/a ratio and suppression of the martensitic transformation of the matrix phase. The fine γ phase microstructure with an average grain size of 0.31 µm showed higher fracture strength and ductility values by 28% and 77% compared to the coarse-grained counterpart with an average grain size of 3.31 µm. The fine dual phase microstructure shows a quasi-linear superelasticity of 4.2% and very small stress hysteresis during cyclic loading, while the coarse dual phase counterpart presents degraded superelasticity of 2.6% and large stress hysteresis. These findings indicate that grain size refinement of the γ phase is an effective approach in improving the mechanical and transformation properties of dual phase Heusler alloys.