Shear Strength of Reinforced Concrete Squat Walls

Squat shear walls are widely used in various structures to resist earthquake loads. However, the relevant design expressions found in building codes and literature do not incorporate the influence of all crucial parameters and provide inconsistent peak shear strength estimations. This study adopts the artificial neural network (ANN) to predict the peak shear strength of squat walls using an extensive database that includes the results of 487 walls with wide-ranging test parameters. The ANN models consider the effect of concrete strength, the wall aspect ratio, vertical and horizontal reinforcements, vertical reinforcement of boundary elements, and axial load ratio. These accurately predicted the available test results. They implemented it to carry out parametric and sensitivity analysis to investigate the effect of the main parameters on the peak strength and to give information about the factors that contribute most to the shear response. In addition, a softened strut and tie method is proposed, considering the variables that substantially influence the shear strength. A nonlinear regression analysis is employed to determine the coefficients of the proposed model using the available database. The performance of the proposed model is measured using the existing models, which results in the best favorable agreement with the test results. Doi: 10.28991/CEJ-2023-09-02-03 Full Text: PD

An Enhanced Source Location Privacy based on Data Dissemination in Wireless Sensor Networks (DeLP)

open access articleWireless Sensor Network is a network of large number of nodes with limited power and computational capabilities. It has the potential of event monitoring in unattended locations where there is a chance of unauthorized access. The work that is presented here identifies and addresses the problem of eavesdropping in the exposed environment of the sensor network, which makes it easy for the adversary to trace the packets to find the originator source node, hence compromising the contextual privacy. Our scheme provides an enhanced three-level security system for source location privacy. The base station is at the center of square grid of four quadrants and it is surrounded by a ring of flooding nodes, which act as a first step in confusing the adversary. The fake node is deployed in the opposite quadrant of actual source and start reporting base station. The selection of phantom node using our algorithm in another quadrant provides the third level of confusion. The results show that Dissemination in Wireless Sensor Networks (DeLP) has reduced the energy utilization by 50% percent, increased the safety period by 26%, while providing a six times more packet delivery ratio along with a further 15% decrease in the packet delivery delay as compared to the tree-based scheme. It also provides 334% more safety period than the phantom routing, while it lags behind in other parameters due to the simplicity of phantom scheme. This work illustrates the privacy protection of the source node and the designed procedure may be useful in designing more robust algorithms for location privac

Alternative Strut and Tie Model for Reinforced Concrete Deep Beams

This paper presents a simple strut and tie model to calculate the shear strength of reinforced concrete deep beams. The proposed model assumes that the shear strength is the algebraic sum of three strength components: concrete diagonal strut, vertical stirrups, and horizontal web reinforcements. The contribution of each strength components was calibrated with the test results of 305 deep beams compiled from previous studies with wide range of geometrical and material properties. The predictions of the proposed model were compared with those of the current codes of practice (ACI-318-14 and ASHTOO 2014) and those of existing model in the literature. Comparisons revealed that the proposed model provided better predictions than other models. The mean of predicted strength to test of the proposed model, the ACI-318-14 model, the ASHTOO 2014 model were 0.98, 0.79, and 0.75, respectively. The corresponding standard deviations were 0.17, 0.28, and 0.49, respectively

Improving the Safety Culture and Climate of Smaller Construction Firms: A Necessary Addition to the OSH Intervention Model

The unsatisfactory safety performance of smaller construction firms has been identified as a challenge that requires further investigation and intervention. There are few studies, if any, that investigate the safety culture and climate of smaller construction firms. This study represents a much needed attempt to clarify the obstacles that prevent smaller construction firms from creating a satisfactory level of safety culture and climate. The study aims to propose a framework that is better suited for smaller construction firms based on literature. To validate the proposed framework, a questionnaire was designed and administered. The findings support the proposed framework and deliver an objective defining criterion that classifies smaller construction firms into small firms and micro firms. Among other factors, the findings suggest that smaller construction firms often lack systematic safety operations due to the absence of safety personnel. Accordingly, a revised occupational safety and health (OSH) model for smaller construction firms has been developed based on the model previously developed by the National Institute of Occupational Safety and Health (NIOSH). It is expected that this study will improve safety intervention programs for smaller construction firms and the safety performance of the construction industry

Coherence Resonance in Optical Feedback Chaos: Hiding Frequency in Chaos Communication

In this chapter, an experimentally and numerically conducted investigation of the existence of high chaotic spiking in the dynamics of semiconductor lasers with AC-coupled optical feedback, the bifurcation diagram by feedback strength attenuation and the bias current as a control parameter was done. A semiconductor laser subjected to an external optical feedback can present a big change of dynamic behaviors, such as periodic and quasi-periodic oscillations, chaos, coherence collapse, and low-frequency fluctuations (LFF’s) that degrade the laser characteristics. The chaotic instability is experimentally investigated on feedback strength as a control parameter, and the resulted dynamic is monostability. Finally, we indicated that the observed chaotic dynamic is a good candidate to hide information in order to investigate the resonance phenomena, which is important for chaos to encrypt data in optical communication, where data disappear when modulated in a chaos carrier. The aim of this chapter is to investigate the encryption area in the chaotic system when the applied frequency is 1–500 MHz, for satisfying the secure communication

Occupational safety basics understanding in oil and gas industry: An evaluation

In project management, risk is a surprise that might be resulted in a good, or bad, impact on a project. However, people tend to consider it a threat. This study is an evaluation work to the understanding of the risk management and safety culture of the construction sector in oil and gas industry in Iraq. A survey questionnaire was prepared, tested, distributed to a sample of engineers, from several engineering specialties, who are working on different levels in the mentioned sector. A high percent of the respondents are safety engineers, and some have a higher university degree, e.g. MS an Ph.D. The collected data then analyzed using different statistical approaches. The results show that there is a good understanding of the safety in general among engineers. However, risk management and planning tools are not understood effectively among the respondents. Moreover, having a higher degree or specializing in different majors have no impact on perceptional understanding of the safety and risk. This study is one of the first steps in studying the occupational safety in Iraq construction and oil and gas industries. Since Iraq is considered for rebuilding after different wars, international firms are in need to understand how safety is managed and to what level it is applied. From this perspective, this study is one of studies that help achieving the firms’ goal regarding safety

Novel quinazolinone derivatives: Synthesis and Antimicrobial Activity

Abstract: This work involves to synthesis novel organic compounds and studies their pharmacological. Approach: The title compound quinazolinone derivatives were prepared by reacting 3 amino of 3-amino-2-methylquinazolin-4(3H)-one (first) with various aldehydes and ketones, and second coupling through diazonium salts with resorcinol or with ethylacetoacetate then cyclized with hydrazine. The starting material 3-amino-2-methylquinazolin-4(3H)-one was synthesized by reacting hydrazine with 2-methyl-4H-benzo[d

Are Construction Managers from Mars and Workers from Venus? Exploring Differences in Construction Safety Perception of Two Key Field Stakeholders

Persisting high rates of worksite accidents and injuries in construction projects indicate the urge to investigate the root causes and revisit safety practices in this industry. Consonance in perceptions and safety approaches has been identified as a fundamental factor in boosting projects’ safety. Discrepancies between how different elements of construction safety are perceived and handled by the key stakeholders, namely managers and workers, could be detrimental to worksite safety. This research studied how, if at all, the perception of four key construction safety components, including 33 sets of pairwise questions, is different in the lens of managers from workers. To explore safety perceptions, 133 construction professionals in the United States participated in the study and expressed their perceptions toward their own and counterparts’ (1) safety knowledge, (2) safety culture and commitment, (3) safety performance, and (4) safety support and communication. The results indicated that massive gaps in safety perceptions do exist between the construction managers and workers (26 out of 33 areas), and the magnitude varies for different safety elements. In all four categories, both managers and workers perceived a superior safety position for themselves and inferior for their counterparts. Further investigations revealed that the common ground between managers and workers is their consensus on proper communication and safety training as the key solutions to address such discrepancies. Construction safety professionals and practitioners can benefit from the results of this study to establish and implement strategies to foster communication and provide more effective safety training to bridge the existing gaps in the perception of safety by managers and workers