Self-compacting concrete (SCC) is known as a high-performance concrete that molds by its weight and without the need for vibration or impact and easily crosses the small spaces between the rebars. ...Various additives have been used in recent research to construct the self-compacting concrete in order to achieve higher strengths and improved performances. Because of the utilization of self-compacting concrete in bulk concreting like dams, silos, and tanks, the optimized use for reducing the final costs of the project is important and essential. A fundamental question in improving the fiber self-compacting concrete behavior is that what is the optimum amount of fiber addition for low fiber concentrations. In this research, the effect of the addition of fiber with concentrations lower than 1,000 gr (100, 250, 500, and 1,000 gr) on the self-compacting concrete behavior with different fiber lengths have been studied. This research examined the effect of the quantity and length of recycled plastic fiber on the compressive strength and tensile resistance of self-compacting concrete. Slump flow experiment L box and sieve and compressive and tensile strength experiment were done on samples. In this study, 13 plans of concrete mixing were surveyed with ratio of water to cement 0.4. One plan without fiber was chosen as a reference sample and 12 self-compacting concrete with plastic Fibers were made in the laboratory with dimensions of 1, 2, 3 cm with their amounts equal 100, 250, 500 and 1,000 g/m
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. Laboratory results showed that increasing the amount and length of fibers led to decreased flowability and passability plus increased detachment in samples. By increasing plastic fibers, compressive strength increased by 8.4% and tensile resistance increased by 4.22%. Their elevation depends on fibers amount. Fiber length did not affect the compressive strength and tensile resistance very much. The increase was such that the tensile strength increased by about 100% and 200% as the length increased from 1 to 2 cm and 1 to 3 cm, respectively. The 1 cm plastic fiber length could be selected as the optimum length for increasing the compressive strength by considering the efficiency.
Steel structures with khorjini beam–column connections, used to be a popular construction practice in Iran. This paper presents a new rigid khorjini connection with reduced beam sections (RBS) for ...earthquake-resistant steel structures. In rigid khorjini connection, two beams pass next to the column faces without interruption and are connected to the column by vertical plates. In this research, Rigid khorjini connections with Reduced beam sections were investigated. RBS method has some disadvantages such as web local buckling and lateral torsional buckling. Therefore, to prevent these weaknesses and improve the performance of khorjini connections with reduced beam sections, web stiffeners were employed. Four different specimens were constructed and tested using IPE 140 profiles for beams: one without an RBS (KHORJINI), one with reduced beam section (KRBS), and two with RBS and web stiffeners (KRBS-HVS and KRBS-DS). Through these experimental tests, it was revealed that all specimens sustained the interstory drift angle greater than 0.06 rad without any significant loss of strength, which indicates that the Rigid khorjini connection with reduced beam sections for IPE140 profiles can perform acceptably under the conditions of AISC regulations and the use of Diagonal and Horizontal-Vertical stiffeners increased the energy dissipation and plastic rotation capacity of connections.
Purpose
To reduce financial and human losses, managing risks associated with earthquakes is essential in practice. However, in using common risk management methods, experts are often faced with ...ambiguities that can create profound challenges for risk management. Therefore, it is necessary to develop a logical and straightforward risk assessment model to provide scientific and accurate answers to complex problems. This study aims to recommend an innovative combined method based on the probability-impact (P-I) approach and intuitionistic fuzzy set theory to identify and prioritize the essential earthquake risks associated with worn-out urban fabrics in the context of Iran.
Design/methodology/approach
The opinions of 15 experts in the fields of civil engineering and urban construction were gathered during brainstorming sessions. These brainstorming sessions were conducted to determine the probability of risks and the effect of identified risks. After calculating the severity of risks using the P-I approach and converting them to intuitionistic fuzzy sets, the risks were measured and prioritized based on their individual scores.
Findings
The study results indicated that risk of damage due to buildings’ age and flooding risk had the highest and lowest priorities in causes of financial damage, respectively. Furthermore, the risk of damage due to building quality (demolition) and building age was the most important. The risk of flooding and damage to communication networks has the lowest importance among causes of fatalities in worn-out urban fabrics.
Originality/value
The study findings and recommendations can be served as a policy and consultative instrument for the relevant stakeholders in the area of urban management.
Background:
The process of temporary accommodation after an earthquake is one of the most important issues in crisis management.
Objective:
This research study attempts to identify and prioritize the ...key risks inherent with the post-earthquake temporary accommodation process in Sanandaj, Iran using the Fuzzy Delphi method.
Methods:
To achieve this goal, first, we examined the previous research on the issue of temporary accommodation after earthquakes and other disasters worldwide in order to determine the current important challenges. Then, the opinions of crisis management experts in 11 areas and 94 questions in the form of Fuzzy Delphi survey questionnaire with Five-point Likert measurement scale were used to rank these challenges. The Delphi panel participants, who responded to the Fuzzy Delphi questionnaire, consisted of 18 experts related to crisis management in executive organizations of Kurdistan province.
Result:
After performing the steps of the fuzzy Delphi method, a basket of important risks in the temporary accommodation process were identified qualitatively and quantitatively, and were prioritized in order of relevance and significance. The results showed that climatic challenges have the highest potential of post-earthquake temporary accommodation risk in the region among of the 11 major risk areas under examination.
Conclusion:
The study’s findings and recommendations can serve as a policy instrument and consultative toolkit for relevant stakeholders.
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