Tulio Coelho, Sofia Maria Carrato Diniz and Francisco Rodrigues
To evaluate the temperature-dependency of the Young’s and shear moduli of concrete after exposure to moderately elevated temperatures using the non-destructive impulse excitation…
Abstract
Purpose
To evaluate the temperature-dependency of the Young’s and shear moduli of concrete after exposure to moderately elevated temperatures using the non-destructive impulse excitation technique (IET).
Design/methodology/approach
The study involved heating the concrete up to 225 °C and measuring the dynamic Young’s and shear moduli using the non-destructive technique of impulse excitation, which measures the natural vibration frequency from a mechanical impulse received by an acoustic sensor. The effects of temperature on the dynamic Young’s and shear moduli were analysed and the importance of the spatial variability of the measured values was also verified.
Findings
The study found that even moderately elevated temperatures (below 225 °C) resulted in a significant permanent reduction in the Young’s modulus of concrete (reduction in the range of 23%–36% for the maximum temperature considered in this research) as well as a modest and permanent reduction in the shear modulus of around 6%. It was also observed that spatial variability of the mechanical properties of concrete plays an important role in the measured values; higher dispersion of the results was found for the values of the Young’s and shear moduli of concrete measured along the height of the beam. The non-destructive test method used in this study was found to be extremely useful in the investigation of heat-related damage in concrete structures for its ease of use, low time consumption and accuracy. The results were consistent with the published literature.
Originality/value
This study provides important insights into the temperature-dependent behaviour of the dynamic Young’s and shear moduli of concrete and highlights the significance of proper consideration of the spatial variability of the measured values. The use of a non-destructive test method for continuous acoustic testing during heating and cooling proved to be effective, and the findings contribute to the fields of materials science and civil engineering in understanding the effects of elevated temperatures on concrete properties. The findings confirm that IET can be easily used to gather important information in the condition assessment and rehabilitation of concrete structures after a fire event. Further studies to foster the application of this technique to real structures are suggested.
Details
Keywords
Tulio Coelho, Sofia Diniz, Francisco Rodrigues and Ruben Van Coile
This paper aims to investigate the state of the art for the reliability evaluation of reinforced concrete beams in a fire situation. Special emphasis is placed on addressing which…
Abstract
Purpose
This paper aims to investigate the state of the art for the reliability evaluation of reinforced concrete beams in a fire situation. Special emphasis is placed on addressing which parameters were considered probabilistically or deterministically, the prescribed probabilistic models for the assumed stochastic variables, the treatment of the heat transfer mechanism, the quantification of the structural fire performance and the assumed target reliability levels.
Design/methodology/approach
Research papers were identified through a search on the Web of Science, Google Scholar and detailed searches within the journals Journal of Structural Fire Engineering, Fire Technology and Fire Safety Journal, supplemented with references known by the authors.
Findings
Considering the state-of-the-art review, gaps in the literature are identified related to (1) the probabilistic evaluation of shear capacity for standard fires and parametric fires, and bending capacity for parametric fires, (2) the absence of reference fragility curves for immediate design application/code calibration and (3) the specification of target safety levels for reliability-based design.
Originality/value
The lack of research papers gathering studies on the reliability of reinforced concrete beams in fire situation makes it difficult to further develop research in the area. The value of this work lies precisely in the collection of the basic information, making it possible to identify gaps to be addressed in future research and the suggestion of a research framework.
Details
Keywords
Enzo Frazzon, Guilherme Luz Tortorella, Ricardo Dávalos, Tulio Holtz and Leandro Coelho
This paper aims to analyze a conceptual framework of supplier-manufacturer relationship in a lean supply chain environment, which considers two different configurations for the…
Abstract
Purpose
This paper aims to analyze a conceptual framework of supplier-manufacturer relationship in a lean supply chain environment, which considers two different configurations for the integration of information and material flows, aiming to better understand the applicability of such kind of approach to realistic cases.
Design/methodology/approach
Two different configurations for the integration of transport and material flows will be comparatively simulated and tested, aiming to better understand scientific implications and the applicability of such kind of approach to realistic cases in terms of performance of delivery service level and lead time.
Findings
The findings indicate that the conceptual model provides a framework to define threshold values of production variability to support the decision-making process regarding finished goods lean strategy. Furthermore, as the conceptual model considers as inputs the process variability of both supplier and customer’s production rates, it allows for the verification of the influence of supplier’s efficiency in the inventory sizing adopted in each case.
Originality/value
This study contributes to the body of literature on lean supply chain by proposing a simulation-based model that analyzes two different theoretical scenarios enabling the assessment of trade-offs among delivery service level, inventory strategy and production stability. This analysis provides theoretical arguments that may be extrapolated to real case situations, and considered other sources of instability that can impact the performance.
Details
Keywords
Victor Silva Corrêa, Maciel M. Queiroz and Helena Belintani Shigaki
This paper investigates if and how entrepreneurs' social capital influences their individual entrepreneurial orientation attributes (innovativeness, proactiveness, and…
Abstract
Purpose
This paper investigates if and how entrepreneurs' social capital influences their individual entrepreneurial orientation attributes (innovativeness, proactiveness, and risk-taking).
Design/methodology/approach
The research method adopted is an exploratory multiple case study. The case chosen is that of an emerging and under-examined entrepreneur, the religious entrepreneur. The study investigates 20 pastors responsible for small enterprise-churches in Brazil.
Findings
Social capital influences individual entrepreneurial orientation, being characterized by a relative paradox. The networks must be dense enough to stimulate entrepreneurs' individual entrepreneurial orientation but not be so dense as to harm innovativeness, proactivity and risk-taking. Further, data show that individual entrepreneurial orientation influences social capital.
Research limitations/implications
One limitation relates to the semi-structured interviews' restricted use. A second limitation is associated with the recognition of churches only as productive enterprises.
Practical implications
This article suggests the significance of incorporating both themes in entrepreneurial education and training programs. It also stresses the appropriateness of religious entrepreneurship as an empirical research field for business scholars.
Originality/value
The contributions are fivefold. First, the authors build exploratory theoretical propositions on the influence of social capital on individual entrepreneurial orientation. Second, they highlight the significance of dense networks for individual entrepreneurial orientation, expanding the literature that supports the relevance of cohesive networks solely to the construct's organizational dimension. Third, the authors suggest that a relative paradox may characterize individual entrepreneurial orientation. Fourth, the authors suggest the existence of recursion between both constructs. Finally, this study is one of the first to examine social capital and individual entrepreneurial orientation, considering innovativeness, proactivity, and risk-taking, which represents a neglected field in benchmarking studies.