Transverse Shear Stiffness of Bolted Cold-Formed Steel Storage Rack Upright Frames with Channel Bracing Members

Accurately evaluating the transverse shear stiffness of cold-formed steel storage rack upright frames is crucial to calculate the frame elastic buckling load, perform earthquake design and serviceability checks. This is especially essential for high-bay racks, which are subjected to large second-order effects, and racks supporting the building enclosure, which are exposed to transverse wind loads. The shear behaviour of these frames is poorly understood and experimental testing is usually required to measure their stiffness. Previous studies have shown that Finite Element Analyses (FEA), solely using beam elements, fail to reproduce experimental test results and may overestimate the transverse shear stiffness by a factor up to 25. In this paper, a commercially used upright frame, with either bolted lip-to-lip or back-to-back channel section bracing members, has been modelled using shell elements. The model is verified against available experimental data and found to accurately predict the experimental shear stiffness with an average error of 7%. Based on the verified FE model, the factors contributing to the frame shear deformation are quantified. The different frame deformations imposed by the test set-ups in the European (EN15512) and Australian (AS4084) standards are both considered. The effects of the bracing lay-out, the bolt bending, local deformations of the uprights and bracing members at the connections on the performance of the upright frames are quantified and discussed

The notion of becoming in mass-housic complexes; the case of mortafa housing, mashhad, Iran

Places are not frozen in time, both mass-housing complexes and their urban contexts are in the state of constant becoming, they begin to change from the very moment they are completed. These changes happen gradually, due to various forces, and at different levels. Based on the Deleuzian ontology of, becoming-in-the-world, the theory of place as assemblage, explores a dynamic conception of place, which is in the state of constant becoming. Place is therefore considered as a three-folded assemblage, which is individually experienced, socially constructed and spatially structured. The present paper aims to explore the process of becoming in the case of an Iranian mass-housing complex known as Mortafa Housing. The process by which this high-rise and luxurious suburban complex, which was the symbol of modernity and urban development, has lost its socio-physical characteristics and has been transformed into an aged residence for low-income, single mothers and seniors. The deployed methodology has been developed based on Dovey's triangular methodology of phenomenology, discourse analysis and spatial analysis. Therefore, the paper starts with a theoretical review of the three related theories on place; Phenomenology of place, Global sense of place and Place as assemblage. The contribution of the study to the limited existing literature grounding the theory of place as assemblage, is to focus on the notion of becoming, itself, rather than take it for-granted. Furthermore, the paper attempts to develop Dovey's triangular methodology in order to understand how the process of becoming can be analyzed in the lifetime of a case. The case study analysis explores the ways in which individuals experience the process of becoming internally, how the hidden socio-political forces affect the process externally and how these introverted and extroverted forces affect the spatial construction of the complex. It also explains how the deployed methodology can pave the way for further research on the assemblage notion of place. The paper demonstrates that it is possible to merge the methodologies, which have theoretically different or even paradoxical approaches toward place, and reveal a holistic assessment about the becoming notion of place. The mapping of the case study clarifies that the processes of becoming are ongoing in a paradoxical way between the Mortafa housing complex and its context. It can, therefore, be predicted that the complex will soon be faced with a decisional dead-end

Biaxial Bending of Cold-Formed Steel Storage Rack Uprights – Part II: Design Methods

This paper uses the results from the parametric studies reported in the companion paper to verify the accuracy of different forms of published direct strength method (DSM) equations. They consist of the classical DSM equations and considering the inelastic reserve capacity into these equations, with and without an extended range of the cross-sectional slenderness. The verifications are made for local and distortional buckling modes. Results show that for all investigated buckling modes, the DSM results in better predictions when the inelastic reserve capacity is considered. The appropriate form of the DSM to predict the biaxial capacity of unperforated cold-formed steel storage rack uprights is discussed

Biaxial Bending of Cold-Formed Steel Storage Rack Uprights – Part I: Parametric Studies and Response

This paper first introduces an advanced finite element model to determine the biaxial bending capacity of cold-formed steel storage rack upright sections. The model is found to accurately predict published experimental results with an average predicted to experimental capacity ratio of 1.02. Second, the validated model is used to run parametric studies and analyse the biaxial response of slender, semi-compact and compact unperforated storage rack upright cross-sections. Analyses are run for local and distortional buckling failure modes only. Ten and four different cross-sectional shapes are analysed for local and distortional buckling, respectively, and nine biaxial bending configurations are considered per cross-section and buckling mode. Results show that a nonlinear interactive relationship typically governs the biaxial bending of the studied uprights. This relationship is discussed in some details and analysed for the different failure modes and cross-sectional slenderness

Barriers to the adoption of new safety technologies in construction: a developing country context

The adoption rate of new technologies is still relatively low in the construction industry, particularly for mitigating occupational safety and health (OSH) risks, which is traditionally a largely labor-intensive activity in developing countries, occupying ill-afforded non-productive management resources. However, understanding why this is the case is a relatively unresearched area in developing countries such as Malaysia. In aiming to help redress this situation, this study explored the major barriers involved, firstly by a detailed literature review to identify the main barriers hampering the adoption of new technologies for safety science and management in construction. Then, a questionnaire survey of Malaysian construction practitioners was used to prioritize these barriers. A factor analysis further identified six major dimensions underlying the barriers, relating to the lack of OSH regulations and legislation, technological limitations, lack of genuine organizational commitment, prohibitive costs, poor safety culture within the construction industry, and privacy and data security concerns. Taken together, the findings provide a valuable reference to assist industry practitioners and researchers regarding the critical barriers to the adoption of new technologies for construction safety management in Malaysia and other similar developing countries, and bridge the identified knowledge gap concerning the dimensionality of the barriers

Research into Satisfaction with Industrial Heritage Renewal Based on the SEM-IPA Model: A Case Study of the Dongguan Jianyuzhou Park

The objective of this study was to establish a satisfaction evaluation model of industrial heritage renewal by evaluating the performance of old industrial buildings after renewal, then judging the adaptability and accuracy of the transformation strategy and putting forward targeted improvement suggestions. The data were collected through a questionnaire survey and analyzed by the statistical package for social science (SPSS) software using a structural equation model (SEM) and importance–performance analysis (IPA). The results show that (1) history, culture, and placeness have the largest average satisfaction and a positive and significant impact on overall satisfaction; (2) the building regeneration effect has a significant impact on overall satisfaction; and (3) social influence, external environmental perception, and economic benefits have no significant effect on overall satisfaction, indicating the need to strengthen public participation for further research into environmental creation, market-based operation, and land conservation. This case study reflects the distinctive features of internationalization and localization, and provides an indication of local practice in China for world urban renewal and architectural heritage theories

On Infiltration and Infiltration Characteristic Times

In his seminal paper on the solution of the infiltration equation, Philip (1969), https://doi-org.proxy.library.uu.nl/10.1016/b978-1-4831-9936-8.50010-6 proposed a gravity time, tgrav, to estimate practical convergence time and the time domain validity of his infinite time series expansion, TSE, for describing the transient state. The parameter tgrav refers to a point in time where infiltration is dominated equally by capillarity and gravity as derived from the first two (dominant) terms of the TSE. Evidence suggests that applicability of the truncated two-term equation of Philip has a time limit requiring higher-order TSE terms to better describe the infiltration process for times exceeding that limit. Since the conceptual definition of tgrav is valid regardless of the infiltration model used, we opted to reformulate tgrav using the analytic implicit model proposed by Parlange et al. (1982), https://doi-org.proxy.library.uu.nl/10.1097/00010694-198206000-00001 valid for all times and related TSE. Our derived gravity times ensure a given accuracy of the approximations describing transient states, while also providing insight about the times needed to reach steady state. In addition to the roles of soil sorptivity (S) and the saturated (Ks) and initial (Ki) hydraulic conductivities, we explored the effects of a soil specific shape parameter β, involved in Parlange's model and related to the type of soil, on the behavior of tgrav. We show that the reformulated tgrav (notably urn:x-wiley:00431397:media:wrcr26009:wrcr26009-math-0001 where F(β) is a β-dependent function) is about three times larger than the classical tgrav given by urn:x-wiley:00431397:media:wrcr26009:wrcr26009-math-0002. The differences between the classical tgrav,Philip and the reformulated tgrav increase for fine-textured soils, attributed to the time needed to attain steady-state infiltration and thus i + infiltration for inferring soil hydraulic properties. Results show that the proposed tgrav is a better indicator of time domain validity than tgrav,Philip. For the attainment of steady-state infiltration, the reformulated tgrav is suitable for coarse-textured soils. Still neither the reformulated tgrav nor the classical tgrav,Philip are suitable for fine-textured soils for which tgrav is too conservative and tgrav,Philip too short. Using tgrav will improve predictions of the soil hydraulic parameters (particularly Ks) from infiltration data compared to tgrav,Philip

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION September

Abstract: Performance-based earthquake engineering is a recent focus of research that has resulted in widely developed design methodologies due to its ability to realistically simulate structural response characteristics. Precise prediction of seismic demands is a key component of performance-based design methodologies. This paper presents a seismic demand evaluation of reinforced concrete moment frames with medium ductility. The accuracy of utilizing simplifi ed nonlinear static analysis is assessed by comparison against the results of time history analysis on a number of frames. Displacement profi les, drift demand and maximum plastic rotation were computed to assess seismic demands. Estimated seismic demands were compared to acceptance criteria in FEMA 356. The results indicate that these frames have suffi cient capacity to resist interstory drifts that are greater than the limit value

Semi-active fuzzy control for seismic response reduction of building frames using variable orifice dampers subjected to near-fault earthquakes

In this paper, a fuzzy-rule-based semi-active control of building frames using semi-active variable orifice dampers (VODs) is presented. Additionally, the consequences of well-known characteristics of near-fault ground motions, forward directivity and fling step, on the seismic response control is investigated. The membership functions and fuzzy rules of the fuzzy controller were optimized by genetic algorithm. To illustrate the efficiency of the proposed fuzzy controller strategy in application and effects of near-fault ground motions, numerical simulation for a 10-story building frame equipped with VODs is presented. The VODs are installed in all storeys to prevent damage to the structure from severe earthquakes. The controlled response of the frame was compared with results obtained by controlling the frame by the classical clipped-optimal control method based on linear quadratic regulator theory. Results revealed that the fuzzy logic controller is capable of improving the structural responses and VODs are promising for reducing seismic responses during near-fault earthquakes. </jats:p