Search results

Simulations exist for the prediction of the behaviour of building structural systems under fire, including two-way coupled fire-structure interaction. However, these simulations do not include detailed models of the connections, whereas these connections may impact the overall behaviour of the structure. Therefore, this paper proposes a two-scale method to include screw connections.

The two-scale method consists of (a) a global-scale model that models the overall structural system and (b) a small-scale model to describe a screw connection. Components in the global-scale model are connected by a spring element instead of a modelled screw, and the stiffness of this spring element is predicted by the small-scale model, updated at each load step. For computational efficiency, the small-scale model uses a proprietary technique to model the behaviour of the threads, verified by simulations that model the complete thread geometry, and validated by existing pull-out experiments. For four screw failure modes, load-deformation behaviour and failure predictions of the two-scale method are verified by a detailed system model. Additionally, the two-scale method is validated for a combined load case by existing experiments, and demonstrated for different temperatures. Finally, the two-scale method is illustrated as part of a two-way coupled fire-structure simulation.

It was shown that proprietary ”threaded connection interaction” can predict thread relevant failure modes, i.e. thread failure, shank tension failure, and pull-out. For bearing, shear, tension, and pull-out failure, load-deformation behaviour and failure predictions of the two-scale method correspond with the detailed system model and Eurocode predictions. Related to combined load cases, for a variety of experiments a good correlation has been found between experimental and simulation results, however, pull-out simulations were shown to be inconsistent.

More research is needed before the two-scale method can be used under all conditions. This relates to the failure criteria for pull-out, combined load cases, and temperature loads.

The two-scale method bridges the existing very detailed small-scale screw models with present global-scale structural models, that in the best case only use springs. It shows to be insightful, for it contains a functional separation of scales, revealing their relationships, and it is computationally efficient as it allows for distributed computing. Furthermore, local small-scale non-convergence (e.g. a screw failing) can be handled without convergence problems in the global-scale structural model.

This study aims to characterize the properties of natural cellulose fiber from the pseudo-stems of the curcuma zedoaria plant.

The fiber was extracted using the biological retting process (cold-water retting). The intrinsic fiber properties obtained were used to evaluate the possibility of using fiber for textile applications.

The average length of a curcuma zedoaria fiber was 34.77 cm with a fineness value of 6.72 Tex. A bundle of curcuma zedoaria fibers was comprised of many elementary fibers. Curcuma zedoaria had an irregular cross-section, with the lumen having a varied oval shape. Curcuma zedoaria fibers had tenacity and elongation value of 3.32 gf/denier and 6.95%, respectively. Curcuma zedoaria fibers had a coefficient of friction value of 0.46. Curcuma zedoaria fibers belong to a hygroscopic fiber type with a moisture regain value of 10.29%.

Extraction and Characterization of Curcuma zedoaria Pseudo-stems Fibers for Textile Application.

This content analysis of 62 local news stories from seven US locations published between March 1 and June 30, 2020, reveals how the migration of seasonal residents and short-term renters into leisure and nature-focused amenity-rich settings during the COVID-19 pandemic changed the social meaning of home for year-round and seasonal or part-time residents. Four themes emerge relating to (a) local economies; (b) health and safety; (c) local government; and (d) insiders and outsiders. These themes are connected to each other in the larger explanatory story of second home real estate morality projects, defined as dilemmas, deliberations, and conflicting considerations made by individual and group stakeholders in the evaluation of acquisition, use, meaning, and dispossession of properties meant for residential use beyond the primary residence. Findings reveal that moral considerations of deservedness and citizenship among local residents and short-term residents are framed as deep and incompatible concerns surrounding economic stability and public health. This COVID-19-induced moral framing of the interplay between economic, health, and social concerns is situated in a cultural-relational analysis of marketplaces, using Viviana Zelizer’s (2005) “connected lives” approach to understanding how everyday economic interactions among and within families and neighborhoods are imbued with social and cultural meaning even in a time of crisis.

This paper aims to produce sustainable sport-hijab or veiling using cotton and bamboo as renewable and eco-material blending with polyester. Due to the unique characteristics of the knitting fabrics, the research focused on constructing the proposed samples using a circular knitting technique with a French terry structure, to achieve comfort, ease of care, good appearance and sustainability in different climatic conditions.

The researchers formed three different knitted samples using yarn count 30/1Ne for cotton and bamboo and 70 dens for polyester yarn, using the same blending ratio of 50:50% (cotton/polyester, bamboo/ polyester and cotton/ bamboo). They tested several mechanical and physical properties (weight, thickness, air permeability, water permeability, electrostatic charges, ultraviolet protection factor, stiffness, pilling resistance and bursting strength).

Using different tools, the researchers statistically analyzed the influence of variables on sample properties, including a Chart line, ANOVA test at p-value = 0.05 and the least significant differences values to identify the effect significantly as well as demonstrate the interaction among the samples at each tested property. Finally, radar chart areas to clarify the preferable sample performance.

The findings declared that blending materials used significantly affected most properties of the produced samples, except for the water permeability and an electrostatic charge. Furthermore, the findings pointed out that blending (cotton or bamboo/polyester) is more efficient and desirable than blending (cotton/ bamboo). Additionally, based on radar charts analysis, the cotton/polyester knitted outperforms other blended materials samples in producing sport-hijab or veiling fabric.