Behavior of Fibrous Reinforced Concrete Splices

Background: The tangent of the relationship between bond stress and displacement (slip) is called the modulus of displacement and gives the basis for the theory. This theory is used to determine the stress distribution along the spliced reinforcement bars. Objective: This research presents a modification on the theory of the modulus of displacement to determine the stress distribution along the spliced reinforcement bond for fibrous reinforced concrete. Methods: 1- General differential equations are derived for concrete stress, stress in reinforcement bars and bond stress between reinforcement bars and surrounding concrete. 2-The general solutions of these D.E. are determined and Excel data sheets are prepared to apply these solutions and determine the concrete, steel and bond stresses. Results: Excel data sheets are prepared to determine the concrete, steel and bond stresses. The stresses are determined along the bar splice length considering the effect of steel fiber content. Conclusion: The maximum concrete stress is obtained at center x=0 and minimum at . Maximum bond stress obtained at and minimum at the center. The maximum steel stress at and minimum at . The value of (σcmax) increased linearly with increasing of (ρ). The concrete stress increased nonlinearly with (ρ%) and linearly with ( fy) and (fc’). Also increasing of (k) and bar diameter have small effects. The value of bond stress decreased linearly with (Qf) and (ρ%).

Guidelines for Geotechnical Finite-Element Modeling

This paper emphasizes on the required guidelines for establishing a geotechnical finite-element model. The steps that must be taken to construct such a model are explained in a flowchart, and the methodology described therein is illustrated by building a model using commercially available finite-element software. Well-documented experimental test data are used to validate the model results. The effects of the geometry plotting, meshing techniques, and boundary locations are assessed by comparing the model results with the experimental results. To date, various geotechnical constitutive models have been proposed to describe various aspects of actual soil behavior in detail, and the advantages and limitations of five such models are discussed. The model results are subjected to an assessment check. The geotechnical modeler can be decided based on the knowledge base that constitutive models will use as the case.

Assessment of Construction Project Complexity

Objective: Project complexity is a crucial factor in project management that presents auxiliary obstacles to reaching project objectives (cost, time, safety, and quality). This study aims at understanding project complexity and factors affecting project complexity. The overall objective of the study is to determine the nature of complexity and characteristics, identify the important complex factors that influence the complexity of the project, factor weight of the complex factors, and develop a proposed construction complexity index (CCI). Methods: According to the literature review, the Analytic Hierarchy Process (AHP) method is used to measure the affecting factors of project complexity. Results: This paper developed an index to measure complexity based on factor weights called construction complexity index (CCI). The validity of this index was verified by studying 3 cases. The construction complexity index (CCI) proposed here allows measuring the complexity of the projects in Egypt. The results of this paper provide guidelines on how to successfully manage the complexity of the project. Conclusion: Project complexity management relates to the challenge of dealing with technical competence, professional diversity, uncertainties, and unforeseen events in project implementation. Project managers, who are critical to effectiveness or failure, need skills such as adaptation, creativity, and flexibility to meet this challenge. Therefore, this study provides guidelines to help practitioners to develop their capabilities in managing complex projects. Moreover, this paper enables participants to identify factors affecting the complexity of projects and how to calculate this complexity through the complex index. The outcomes of this study can be used by practitioners to develop a complexity assessment and management tool, which would enable industry practitioners to allocate resources effectively on complex construction projects. This research aimed to develop a measure by which the complexity of construction projects in Egypt can be evaluated and establish guidelines on avoiding complexity in projects.

Risk Management Strategies in Construction Organizations

Background: Construction projects are among the riskiest businesses due to the number of factors involved that are difficult to control; hence, the popularity of risk management as part of the decision-making process in construction organizations is increasing. Despite the advancements, there are various risks involved that lead to project failure. Aim: Thus, this study aims to assess the risk management strategies in construction organizations in the Gaza Strip, Palestine. Methods: Seventy questionnaires were distributed after subjecting them to pretesting and pilot study that confirmed the validity and reliability of the questions. The target respondents included engineers and consultants from the construction organizations, Ministry of Works and Housing, and international agencies. The questionnaire was retrieved with a 65.71% response rate. Results: Results indicated that the most popular method of risk factor determination in the Gaza Strip is the “checklist” (RII=84%). For tools/methods of risk analysis, relying on experience in the direct assessment is the most prominent, with an RII of 78%. For the methods of avoiding risk before the project implementation, dependence on experience in the work for preparing and planning was ranked highest (having RII of 81.6%). Finally, follow-up on the implementation to avoid rework, with an RII of 77.6%, was ranked highest among other factors of avoiding risk during the construction projects implementation. Conclusion: This study highlights the key risk management strategies that will be beneficial for the construction industry stakeholders to resolve the unwanted risk failures in the construction industry.

Effect of Waste Clay Brick Powder on Physical and Mechanical Properties of Cement Paste

Background: Investigations on the use of waste clay brick powder in concrete have been extensively conducted, but the analysis of waste clay brick powder effects on cement paste is limited. Materials and Methods: This paper discusses the effects of waste clay brick powder on cement paste. Fragmented clay bricks were grounded in the laboratory using a ball mill and incorporated into cementitious mixes as partial replacement of Ordinary Portland Cement. Workability, consistency, setting time, density and compressive strength properties of paste mixes were investigated to better understand the impact of waste clay brick powder on the cementitious paste. Four cement replacement levels of 2.5%, 5%, 7.5% and 10% were evaluated in comparison with the control paste. The chemical and mineral compositions were evaluated using X-Ray Fluorescence and X-Ray Diffractometer, respectively. The morphology of cement and waste clay brick powder was examined using a scanning electron microscope. Results: The investigation of workability exhibited a reduction of slump attributed to the significant addition of waste clay brick powder into the cementitious mixes, and it was concluded that waste clay brick powder did not significantly influence the density of the mixes. In comparison with the control paste, increased values of consistency and setting time of cement paste containing waste clay brick powder confirmed the information available in the literature. Conclusion: Although waste clay brick powder decreased the compressive strength of cement paste, 5% partial cement replacement with waste clay brick powder was established as an optimum percentage for specimens containing waste clay brick powder following curing periods of 7 and 28 days. Findings of chemical composition, mineral composition and scanning electron microscopy of waste clay brick powder demonstrated that when finely ground, fragmented clay bricks can be used in concrete as a pozzolanic material.

Characterization of the High Swelling Green Clay in the Vicinity of Amman Area

Introduction: Jordan is awarded huge areas in the north and western part of the country in which brown and green clay is dominant. This research focuses on the problems and behaviour of the green clay only. The main problem of the green clay is its high swelling pressure which is the main cause of excessive settlement and wall cracks in buildings, especially during the wet season. Methods: This study aims to investigate the engineering properties and behaviour of the green clay deposits in the Amman area, which will serve as a guide for both geotechnical and structural engineers when preparing the foundation design. Results: Based on the consolidation test, the investigated green clay showed high swelling pressure of 3.11 kg/cm2, liquid limit (LL) of 73%, plasticity index (PI) of 40%, the shrinkage limit (SL) of 12%, and liquidity index (LI) of 0.125. The moisture content at saturation is 35.14%, while the natural moisture content is 28%, dry density is 1407 kg/m3, cohesion (C) is 0.20 kg/cm2 and unconfined compressive strength is 1.05 kg/cm2. The XRD results of the clay size fraction have confirmed the presence of the expansive clay mineral smectite as the essential clay mineral together with kaolinite. Results provide a general understanding of the behaviour and properties of the green clay, and the regression analysis showed good correlations between the liquid limit and initial moisture content with the compression index and also between the initial void ratios with the swelling index. Conclusion: Changes in the volume are due to the unsaturation level of clay when provided with initial water content.

Increasing Value of Façade at Green Hotel Building Based on Value Engineering

Background: Of a total of 180 countries in the world, Indonesia is ranked 116th in the EPI ranking. This paper describes the innovative design of a high-rise hotel building that carries a green building concept. which utilizes the outer wall area of the hotel building as an object in this study. Objective: The main design of this project is the creation of an innovative high-rise hotel building with attention to architectural, structural, and lighting system aspects as well as energy efficiency from direct sunlight, which will be processed into a source of electrical energy. Materials and Methods: Application of analysis through value engineering case studies and application of green building methods, with qualitative methods. This paper focuses on factors related to energy sources and environmental sustainability and calculates life cycle costs concerning case study designs. The goal is to reduce the use of electrical energy sources from PLN which have an impact on nature preservation, by carrying out the concept of environmentally friendly buildings, by utilizing the facade wall area with the application of Photovoltaic. Results: The results obtained a percentage of ≤ 6.21%, with the use of Photovoltaic material as much as 100%. Conclusion: The facades (east and west) generate ± 1,050 KVA of electricity from the Solar Power Plant and reduce the use of electricity from PLN by 991 KVA, out of a total of 2,041 KVA. It can be concluded that the decrease obtained is 47.32%.

Analytical Optimization Model to Locate and Design Runway-Taxiway Junctions

Aims: Air traffic and airport operations are expected to experience significant growth worldwide in the upcoming years. One of the possible approaches to adapt to this demand-led growth in the sector, while guaranteeing optimal levels of airport services and operations safety, is to maximize the capacities of busy airport infrastructures (in particular runways) by evacuating them in the shortest time possible to be ready for hosting next operations. Background: The main research areas in this field range from statistical risk analyses based on the registered accidents databases to simulation analyses modelling the behaviour of the aircraft during landing operations. Objective: The main objective of this study is to determine precisely the optimal distances of runway-taxiway junctions from the runway’s threshold, according to numerous impact parameters such as airport climate pattern, operating aircraft categories, infrastructure type, and capacity, route connections, operating costs, and associated risks. Methods: The authors developed a mathematical model with the goal of simulating the dynamic behaviour of the aircraft during landing and possible consequences introduced by the presence of contaminants over the pavement surface, by calculating their braking distances, and finally to optimize the use of existing infrastructures, specially runway-taxiway junctions, of a commercial airport. In this regard, the interactions between landing gear, pavement, and fluid were carefully analysed. The dynamic pavement skid resistance values in wet pavement conditions were evaluated for optimizing the required landing distances, which are setting the base for optimizing the location of the taxiway junctions. An Italian international airport was selected as the case study to be simulated by the developed model in order to optimize its runway capacity and maximize its rate of operations. Results: In the process, two different scenarios are simulated with the developed model; a modified design of an existing runway and an alternative design solution for constructing a new runway. The developed model offers improvements for both scenarios with respect to the current runway configurations in terms of reduction in mean rolling distances. The simulation of the selected case study shows that the taxiway modification scenario achieves a reduction of 23% in the mean rolling distance for wet and 25% for dry pavement conditions. While, for designing a new runway, greater reductions of 27% for wet and 39% for dry pavement conditions are obtained due to the higher flexibilities and degrees of freedom in designing a runway from the beginning. Conclusion: The developed model can precisely propose new configurations of the runway-taxiway junctions with lower mean rolling distances, which lower the operation costs and fuel consumption, decrease the runway evacuation times and increase the capacity of the airfield. The main advantage of this model is its ability to cover a wider spectrum of boundary conditions with respect to the existing models and its applicability for designing new runways, plus to optimize the configuration of existing infrastructures in order to satisfy the evolution of the industry.

A Comprehensive Analysis Structure for the Design of Masonry Arches

Background: Structural masonry framing has the potential to be an advantageous design technique for new constructions. The realization of this potential requires both design modernizations and accessible analysis methodologies. The focus and understanding of masonry frames have been directed towards the management and preservation of cultural heritage. This has resulted in an assessment approach to the analysis and duality of the term “masonry” to describe both a material and a method of construction. Objectives: The objective of this work is to differentiate masonry as a method and masonry as a material and to use this differentiation to present a comprehensive method-based analysis structure for masonry arches that is formulated around the need to control and optimize the system. Methods: This work presents an analysis approach that defines and utilizes kinematic equilibrium to establish determinant systems. This is achieved through the inclusion of a loading variable to a defined mechanical condition of the arch. The solution to the equilibrium equation sets is evaluated for admissibility through the examination of the thrust line and arch geometry. The simplified analysis is formulated into a simple software structure, a first-order assessment strategy, a characterization technique to link experiment and theory, and carried to dynamic modeling. Results: The results of the approach are the foundation and blueprint for a comprehensive, efficient, and adaptable structural analysis platform designed for the structural analysis of masonry frames. Conclusion: The developed analysis approach and supporting applications cover the base requirements for promoting the application of masonry frames for new constructions.

Determination of Creep Behavior of Concrete Beams Made with Rice Husk Ash

Background: Creep in concrete is a long-term deformation under sustained loading. It is influenced by many factors, including constituent materials, environmental conditions, among others. Whenever there is an alteration in the convectional concrete preparation process, the creep characteristics need to be realistically assessed. In the present construction, rice husk ash has been used for partial replacement of cement in concrete production. This is because its properties of both tensile and compressive strength in concrete have been tested and found comparable with plain concrete. However, durability characteristics such as creep, which take place in the long run, have not been realistically assessed. Therefore, it is important to study the creep of rice husk ash concrete, which will further help in the development of a creep prediction model for such concrete for use by design engineers. Objectives: Rice husk ash was used as supplementary cementitious material in concrete, and the creep behavior was studied with the aim of producing a creep prediction model for this concrete. Methods: The cement was replaced with 10% of rice husk ash in concrete with a design strength of 30MPA. Reinforced concrete beams were cast and loaded for flexural creep 35 days after casting. The loading level was 25% of the beam’s strength at the time of loading. The creep observation was done for 60 days. The rice husk used was obtained locally from Mwea irrigation scheme in Kenya. The experiments were carried out in our school laboratory at Jomo Kenyatta university of Agriculture and Technology. Results: The creep strain data of rice husk ash concrete beams was obtained with the highest value of 620 micro strain for 60 days. The results were used to develop a creep prediction model for this concrete. Conclusion: A creep prediction model for rice husk ash concrete has been developed, which can be adopted by engineers for class 30 of concrete containing rice husk ash at a 10% replacement level.