Publications

Con el fin de confirmar la utilización de una fibra de acero para reforzar un hormigón, se puso en práctica un método consistente en un test de resistencia al impacto, sencillo, práctico y económico. Los resultados obtenidos indicaron que existe una relación logarítmica entre la tenacidad a flexión (E^..^.) y la energía (Ej) de impacto para estos hormigones. En la realización de este estudio se tuvieron en cuenta tres factores diferentes en lo concerniente a las fibras, con extremo en forma de gancho, con relación longitud/diámetro (mm/mm): 30/0,50:60/0,80y 50/0,60. Las fibras se añadieron al cemento en cuatro porcentajes en volumen diferentes: 0,5, 1,0, 1,5 y 2,0 %. A la vista de los resultados obtenidos, puede decirse que las fibras mejoran, tanto la resistencia al impacto, como la flexión en el hormigón, habiéndose establecido, asimismo, una buena correlación entre la energía de resistencia a flexión y la energía de impacto.

No abstract is provided for this article.

An experimental study was conducted to predict the flexural strength of corroded full-scale reinforced concrete (RC) beams. Two different concrete strength levels at two different steel ratios were tested for different corrosion levels ranging from 0 to 17%. An accelerated corrosion aging method was applied to corrode the reinforcing bars embedded in concrete. The actual corrosion levels were obtained by breaking the concrete and extracting the reinforcing bars. A practical model was developed for the prediction of the flexural strength of corroded RC beams. The developed model predicted the experimentally obtained flexural strength of corroded beams found in the literature well. The results revealed that the structural behavior of corroded RC beams requires consideration of the corrosion levels at both the tensile bars and the stirrups (which are more exposed to corrosion because of their use as outer reinforcing bars) and have significant effects on the flexural strength of corroded RC beams.

The effect of silica fume on the properties of synthetic fiber-reinforced concrete was assessed. Two fiber types were used: fibrillated polypropylene fibers and polyethylene-terphalate polyester fibers. Various fiber volume fractions were examined. Fiber volumes ranged from 0 to 0.6%, and fiber length was 12 mm (1/2 in.). Silica fume was used as partial replacement of portland cement on an equal-mass basis at 0, 5, 10, and 25%. The fresh mixtures were tested for slump, inverted slump cone time, and air content. The hardened concrete material was tested for compressive and flexural behaviors as well as impact resistance. Rapid chloride permeability was also measured. The purpose of the experimental investigation was to assess the suitability of synthetic-fiber silica-fume concrete for application in bridge-deck overlays and other applications for which the mechanical properties and permeability are important. The results indicate that silica fume is useful in improving the effectiveness of fiber reinforcement of concrete and reducing its permeability.

No abstract is provided for this article.

The main disadvantage of high-strength concrete is its highly brittle behavior and this can beovercome by adding fibers to the concrete. This would also improve some other mechanical properties of high-strength concrete such as tensile strength and compressive strength. These properties are not very well established for high-strength steel-fiber reinforced concrete (HSFRC) yet. In this study the influence of silica fume on the properties of HSFRC were investigated by using silica fume of two different percentages and three different hooked-end fibers namely, 30/0.50, 60/0.80 and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different volume percentages of 0.5, 1.0 and 2.0 by volume of concrete. The results indicated that there is a linear function between splitting tensile strength (F splt) and volume percentage of fibers (V f) [i.e. F plt = A(V f) + B, where A and B are correlation coefficients] as well as between splitting tensile strength (F splt) and compressive strength (F c) of plain series A concrete [i.e. F splt = C (√F c) + D, where C and D are correlation coefficients]. These relations can describe the development of splitting tensile strength of HSFRC containing no silica fume, 5% silica fume and 10% silica fume by weight of cement. On the other hand, although silica fume has an effect on compressive strength, volume percentage and aspect ratio of steel fibers has little effect.

Prevention through Design (PtD) and Design for Safety (DfS) are now being considered in relation to occupational health and safety and building design. A recent collection of studies suggests that certain decisions made by designers during the design process are at the root of many risks. A study was undertaken to relate falls from height to the conventional design process for reinforced concrete buildings. This was achieved by dividing the building design process into stages. During the design phase, input was gathered from architects and engineers working in the sector. Accident types were identified based on studies of occupational accident investigation reports from the Ministry of Labor. Of the 15 types of fall from height accidents studied, 12 were attributed to design decisions. Of these, 6 different accident types were associated with 5 or more design decisions, while 2 of these were associated with 3 or 4 design decisions. The remaining 4 types were linked to only 1 design decision.

The effects of aggregate type and size are important parameters in the formation of interfacial transition zone (ITZ) structure and subsequently in the failure process of concrete. The influence of surface, rigidity and size of aggregates and water/cement (w/c) ratio of the matrix on bond strength at the ITZ and the interrelationship between the bond and the matrix in the failure process of concrete under uniaxial compression were studied. For this purpose a series of experiments were designed and carried out on mortars (with two different w/c ratios) containing single spherical steel aggregates. The ITZ properties and the failure process of concrete were investigated by means of tensile and compressive strength, and stress–volumetric strain measurements. It was observed that the effect of aggregate properties (high modulus of elasticity, smooth surface texture and size) on the weakness of ITZ and the failure process of concrete are of paramount importance for low w/c ratio composites. The effect of reduced bond properties was reflected in lowered critical stress levels for the low w/c ratio composites with larger aggregates.

The construction industry has continuously changed its work processes, methods, techniques and associated hazards. In addition, the way in which work is carried out on construction sites varies from project to project. As a result, it is difficult to prevent workplace accidents. What is worrying is that the majority of hazardous situations that arise as a result of decisions made during the design phase are not identified until construction begins. According to studies carried out around the world, some of the hazardous situations in construction are due to decisions made during the design process. The aim of this study was to minimise the hazards that arise from design decisions and cause occupational accidents. To this end, a system has been developed that operates in a BIM environment used by designers during the design phase. Thus, if a designer makes a decision that could cause a hazard, he/she would be warned by the BIM software. Therefore, in terms of occupational health and safety, safer buildings should be designed. This study uses multi-storey building projects and a system that detects and alerts on design decisions that cause fall accidents. The study concluded that most of the hazards that cause falls can be identified at the design stage. Consequently, the majority of these hazards can be eliminated through alternative design recommendations.

For the Jordanian government, meeting the growing demand for goods and services on its own is very difficult, leading to the increased dependence on other sectors of society. This research is aimed at understanding the critical success factors of local public-private partnership projects, identifying the most vital risk factors affecting projects, and establishing a quantitative model for risk assessment. The model can assist public-private partnership contributors by transforming the basic risk assessment principles into a more facilitated and systematic arithmetical based approach. The results showed that the risk factors with the highest ranks (respectively) are transfer phase, organizational risks, financing phase, project management risks, and feasibility study phase. The research is ultimately aimed at developing a framework for the risk evaluation of public-private partnerships within the construction industry in Jordan.

No abstract is provided for this article.

Value of a product, such as a component of a building, reflects on owner's desire to retain and obtain the product, and this introduces subjective aspects to the value. The value of a constructed facility depends on how much the design details of its components agree with the value system of the client. Traditionally, selection of design details is performed by the designers with little consultation with the client. A successful selection of components of construction needs a knowledge of design alternatives, components' criteria and utilities and agreement with the value system of the client. Therefore, determination of value of a constructed facility lends itself to a knowledge based application. This paper presents a knowledge based system called VOBE for the determination of the value of the envelope of a residential building based on the client's value system. To the user VOBE presents design alternative details for each component of the envelope and with the input/confirmation of his/her value system it reports the costs and values of the components of the building envelope.

This research is aimed at evaluating two different scenarios, firstly, appraising the impacts of employing the concepts of Total Quality Management (TQM) to the construction projects in Saudi Arabia. The results of the study were obtained through utilization of a descriptive analytical approach, where 300 questionnaires were distributed to engineering firms and companies with a response rate of 200 questionnaires, hence achieving the study sample for this research. The data gathered was analyzed by applying the Statistical Package for Social Science (SPSS) program and calculating the Relative importance index (RII) and the mean values. From the research conducted, the outcomes showed that the management’s ability to commit using TQM while applying BIM obtained a relative importance of (0.717), while the relative importance for the management’s ability to commit using TQM without the application of BIM is (0.552). The results showed that construction projects in Saudi Arabia still sustain setbacks from applying TQM concepts and suffer from the lack of administrative, scientific and technical applications. In a second scenario, a hybridized support vector regression (SVR) Harris-hawks optimization (HHO) (i.e., SVR-HHO) were used to predict the TQM. The performance accuracy of the models was checked through three different evaluation metrics namely; mean square error (MSE), correlation co-efficient (CC) and Nash-Sutcliffe efficiency (NSE). the hybridized emerging SVR-HHO outperformed the other two data driven approaches in both the training and testing stages based on the employed evaluation metrics. Overall, the obtained results showed that both the machine learning and metaheuristic approaches were capable of predicting TQM.

Effects of coarse aggregate size and water/cement (w/c) ratio of the matrix on the formation of interfacial transition zone (ITZ) and subsequently on the failure process of concrete under uniaxial compression were studied. For this purpose, a series of experiments were designed and carried out on mortars with two different w/c ratios containing single spherical steel aggregates of different sizes. The ITZ properties and the failure process of concrete were investigated through tensile strength tests both before and after compressive preloading, stress–axial strain, stress–volumetric strain and stress–lateral strain measurements. It was observed that ITZ becomes critical for larger aggregates and lower w/c ratio mortar matrices. The negative effect of smooth surface texture of the aggregate and the large difference between aggregate and matrix moduli of elasticity on the properties of ITZ is of paramount importance for low w/c ratio composites. The effect of reduced bond properties of ITZ relative to its matrix was reflected in the lower critical stress levels for the low w/c ratio composites with larger aggregates.

This review paper synthesizes the existing literature on the integration of smart cameras within digital quality management systems (QMS) for the construction industry. It provides an overarching perspective on how digital QMS, enhanced by smart camera technology, addresses key challenges in construction quality, safety, and efficiency. The paper begins by exploring the general benefits of digital QMS in construction, emphasizing the role of smart cameras in automating process monitoring and issue detection. It then categorizes the literature on various types of smart cameras and their broad capabilities, such as image recognition and real-time analysis, in the context of construction. The review highlights the prevalent themes in the application of smart cameras in construction, such as site safety monitoring and progress assessment, drawing on common findings from existing studies. Further, it identifies the main challenges highlighted in the literature, including cost implications, privacy concerns, and the need for technical expertise. The paper underscores the gaps in current research, particularly in the integration of smart cameras with other emerging technologies like drones and wearable devices. It concludes by emphasizing the need for continued research and development to enhance the effectiveness and usability of smart cameras in digital QMS for construction, suggesting areas for future investigation.

Mega transport infrastructure projects (MTIP) which inherent uncertainty and complexity, are in practice all overall the world. These projects concerning their nature show political sensitivity and involve diverse group of stakeholders with conflicting interests. In such situations, decision-making becomes extremely difficult, as the necessary knowledge base for making adequate decisions is lacking due to both uncertainty and conflict of interests. This study aims to identify the stakeholders and their interests, analysing stakeholders' relationships, assessing stakeholders' influences, and practicing stakeholder engagement (SE) in MTIP. In SE there are diverse approaches like operational, practical, and conceptual which will be reviewed in the literature. A model of framework will be proposed to provide new perspectives for identifying the precise interrelationships between the SEs, facilitate the complex processes and guide senior management in meeting project objectives. The proposed framework will also provide an effective SE approach to accommodate stakeholder analysis in MTIP for the planning, decision making and implementation of the project, so as to establish clear project priorities.

This article utilizes gene expression programming (GEP) technique to develop a prediction model in order to automate estimating the construction cost of water and sewer replacement/rehabilitation projects. A database gathered for developing the model was established on the basis of data related to 210 actual water and sewer projects obtained from the City of San Diego, California, USA. To verify the predictability of the GEP model, it was examined to estimate the cost of the projects that were not included in the modelling process. Sensitivity analysis technique and professional experiences were employed to determine the contributions of the qualitative factors and quantifiable parameters affecting the cost estimate. The proposed model with correlation coefficient of 0.8467 is adequately capable of estimating the cost of water and sewer replacement/rehabilitation projects. The GEP-based design equation can easily be used for predesign purposes to help allocate budgets and available limited resources effectively.