Incorporating inflation rate in construction projects cost: Forecasting model.

Over time, the change in the inflation rate causes cost overruns by deviating the prices of goods and services in construction projects that require practitioners to make budgeting revisions. Hence, this study aims to develop a construction rates forecasting model that can incorporate the changing impact of the inflation rate on construction rates and predict the prices in a particular year, which can be adjusted when developing the Bill of Quantities. Following the time series analysis standards, a mathematical model was developed using MATLAB for forecasting. Construction rates, building prices, labour wages and machinery rates were forecasted from 2020 to 2025 based on the data collected from 2013 to 2019. Akaike information criterion was used to validate the self-developed construction rate forecasting model. It was revealed that the model yielded better results when the construction rates were compared with the autoregressive integrated moving average time series model results. The rates forecasting model may be used for any construction project where rates are affected by the inflation effect.

Characteristics-Based Framework of Effective Automated Monitoring Parameters in Construction Projects.

The construction industry is moving toward digitalization, and technologies support various construction processes. In the automated construction progress monitoring domain, several modern progress measurement techniques have been introduced. However, a hesitant attitude has been observed toward its adoption. Researchers have highlighted lack of theoretical understanding of effectual implementation is one of the significant reasons. This study aims to analyze general technological parameters related to automated monitoring technologies and devise a theoretical-based conceptual framework explaining the aspects affecting the adequate operation of automated monitoring. The study has been executed by following a systematic inline process for the identification of effective parameters, which include a structured literature review, semi-structured interviews, pilot survey, questionnaire survey, and structural equation modeling (SEM)-based mathematical model. A refined conceptual framework has been devised with 21 effective parameters under five significant categories, i.e., "Target Object," "Technical," "External Interference," "Occlusions," and "Sensing." A knowledge framework has been established by adopting the SEM technique, which is designed on the characteristics-based theme. This conceptual framework provides the theoretical base for practitioners toward the conceptual understanding of automated monitoring processes related to technological parameters that affect the outcomes. This study is unique as it focused on the general criteria or parameters that affect the performance or outcomes of the digital monitoring process and is easily understandable by the user or operator.

Safety management implementation drivers for construction projects: a structural equation modelling approach.

The construction industry is one of the hazardous fields due to its exceptional environment. Therefore, this work aimed to assess the essential drivers needed for employing safety management in the Palestinian construction industry. The drivers for safety management were recognized from earlier literature, where the questionnaires were dispersed to professionals from construction projects. The exploratory factor analysis (EFA) technique was then performed to contextually adjust the identified drivers. The results showed that safety management drivers could be categorized into three constructs: management, awareness and policy. In addition, partial least squares structural equation modelling (PLS-SEM) was performed to generate the safety management driver's model. The results indicated that management drivers were vital drivers for adopting safety management. The study's findings would act as a reference for construction stakeholders to decrease danger and enhance the construction project's success via implementing safety management drivers.

Modelling and Optimization for Mortar Compressive Strength Incorporating Heat-Treated Fly Oil Shale Ash as an Effective Supplementary Cementitious Material Using Response Surface Methodology.

Fly oil shale ash (FOSA) is a waste material known for its pozzolanic activity. This study intends to investigate the optimum thermal treatment conditions to use FOSA efficiently as a cement replacement material. FOSA samples were burned in an electric oven for 2, 4, and 6 h at temperatures ranging from 550 °C to 1000 °C with 150 °C intervals. A total of 333 specimens out of 37 different mixes were prepared and tested with cement replacement ratios between 10% and 30%. The investigated properties included the mineralogical characteristics, chemical elemental analysis, compressive strength, and strength activity index for mortar samples. The findings show that the content of SiO2 + Al2O3 + Fe2O3 was less than 70% in all samples. The strength activity index of the raw FOSA at 56 days exceeded 75%. Among all specimens, the calcined samples for 2 h demonstrated the highest pozzolanic activity and compressive strength with a 75% strength activity index. The model developed by RSM is suitable for the interpretation of FOSA in the cementitious matrix with high degrees of correlation above 85%. The optimal compressive strength was achieved at a 30% replacement level, a temperature of 700 °C for 2 h, and after 56 days of curing.

Occupational health and safety practice in infrastructure projects.

Objectives. This research intends to investigate the responsibilities of the parties engaged in the implementation phase of the infrastructure projects in occupational health and safety, i.e., the consultant and contractor. Methods. A questionnaire was developed through the selection and modification of the responsibilities from the literature review. Results. The statistical analysis results show that the consultants and contractors both ranked the item 'The owner requires the contractor to implement the occupational safety standards within the bid' first in the owner responsibilities, having 0.67 relative importance index (RII). In the responsibilities of the consultant, the first ranked item was 'The consultant has a role in adopting occupational safety plans and contingency plans', having 0.66 RII. In the responsibilities of the contractor, the first ranked item was 'The contractor shall provide the insurance cover for all project crews', having 0.71 RII. In the responsibilities of the workers, the first ranked item was 'Workers know the handling of tools and equipment within the project', having 0.59 RII. Conclusion. Overall, there was general agreement between consultants and contractors to classify and arrange items because both face the same conditions and have the same working environment.

Health and safety improvement in construction projects: a lean construction approach.

Objectives. Lean construction techniques have been considered an effective approach and strategy to reduce accidents in construction projects. This article aims to investigate the application of the lean construction principle and its impact on occupational health and safety. Methods. To achieve the aim, an analytical descriptive method was used. The data were collected through a questionnaire, with 70 respondents who were chosen using a random stratified sample method. The questionnaire evaluated the perception of contractors and consultants about the important lean construction factors and their impact on construction project safety. Results. There is an agreement that the application of lean construction techniques can be impeded by challenges like lack of lean construction knowledge, complexity, misconception about lean construction and difficulties in changing employees. Conclusions. The study identified strategies that could be used to address these challenges that will improve the safety of construction projects. These include enlightenment on benefits of the lean practice, publication of improvements realized from lean practice, training, workers' involvement and empowerment, persistence, robust planning and gradual implementation.

Artificial Neural Network (ANN) and Finite Element (FEM) Models for GFRP-Reinforced Concrete Columns under Axial Compression.

In reinforced concrete structures, the fiber-reinforced polymer (FRP) as reinforcing rebars have been widely used. The use of GFRP (glass fiber-reinforced polymer) bars to solve the steel reinforcement corrosion problem in various concrete structures is now well documented in many research studies. Hollow concrete-core columns (HCCs) are used to make a lightweight structure and reduce its cost. However, the use of FRP bars in HCCs has not yet gained an adequate level of confidence due to the lack of laboratory tests and standard design guidelines. Therefore, the present paper numerically and empirically explores the axial compressive behavior of GFRP-reinforced hollow concrete-core columns (HCCs). A total of 60 HCCs were simulated in the current version of Finite Element Analysis (FEA) ABAQUS. The reference finite element model (FEM) was built for a wide range of test variables of HCCs based on 17 specimens experimentally tested by the same group of researchers. All columns of 250 mm outer diameter, 0, 40, 45, 65, 90, 120 mm circular inner-hole diameter, and a height of 1000 mm were built and simulated. The effects of other parameters cover unconfined concrete strength from 21.2 to 44 MPa, the internal confinement (center to center spiral spacing = 50, 100, and 150 mm), and the amount of longitudinal GFRP bars (ρv = 1.78-4.02%). The complex column response was defined by the concrete damaged plastic model (CDPM) and the behavior of the GFRP reinforcement was modeled as a linear-elastic behavior up to failure. The proposed FEM showed an excellent agreement with the tested load-strain responses. Based on the database obtained from the ABAQUS and the laboratory test, different empirical formulas and artificial neural network (ANN) models were further proposed for predicting the softening and hardening behavior of GFRP-RC HCCs.

Axial Compressive Strength Models of Eccentrically-Loaded Rectangular Reinforced Concrete Columns Confined with FRP.

The majority of experimental and analytical studies on fiber-reinforced polymer (FRP) confined concrete has largely concentrated on plain (unreinforced) small-scale concrete columns, on which the efficiency of strengthening is much higher compared with large-scale columns. Although reinforced concrete (RC) columns subjected to combined axial compression and flexural loads (i.e., eccentric compression) are the most common structural elements used in practice, research on eccentrically-loaded FRP-confined rectangular RC columns has been much more limited. More specifically, the limited research has generally been concerned with small-scale RC columns, and hence, the proposed eccentric-loading stress-strain models were mainly based on the existing concentric-loading models of FRP-confined concrete columns of small scale. In the light of such demand to date, this paper is aimed at developing a mathematical model to better predict the strength of FRP-confined rectangular RC columns. The strain distribution of FRP around the circumference of the rectangular sections was investigated to propose equations for the actual rupture strain of FRP wrapped in the horizontal and vertical directions. The model was accomplished using 230 results of 155 tested specimens compiled from 19 studies available in the technical literature. The test database covers an unconfined concrete strength ranging between 9.9 and 73.1 MPa, and section's dimension ranging from 100-300 mm and 125-435 mm for the short and long sides, respectively. Other test parameters, such as aspect ratio, corner radius, internal hoop steel reinforcement, FRP wrapping layout, and number of FRP wraps were all considered in the model. The performance of the model shows a very good correlation with the test results.

Utilization of Crumb Rubber and High-Volume Fly Ash in Concrete for Environmental Sustainability: RSM-Based Modeling and Optimization.

Waste tire and fly ash (FA) are two waste materials whose disposal and rapid rate of accumulation are among the pressing sources of concern and threat to the environment. Although much research exists on the use of these materials in cementitious composites, very little literature is available on the effectiveness of combining them in high volumes for concrete production. This work aimed to utilize crumb rubber (CR) from waste tires as a partial replacement of fine aggregate at 15%, 22.25%, and 30% by volume, and high-volume fly ash (HVFA) replacement of cement at 50%, 60%, and 70% (by weight of cementitious materials) to produce high-volume fly ash-crumb rubber concrete (HVFA-CRC). Using the central composite design (CCD) option of the response surface methodology (RSM), 13 mixes were produced with different combinations and levels of the CR and FA (the input factors) on which the responses of interest (compressive, flexural, and tensile strengths) were experimentally investigated. Furthermore, the composite influence of CR and HVFA on the workability of the concrete was assessed using the slump test. The results showed a decline in the mechanical properties with increasing replacement levels of the CR and HVFA. However, up to 22.25% and 60% of CR and HVFA replacements, respectively, produced a structural HVFA-CRC with a compressive strength of more than 20 MPa at 28 days. Response predictive models were developed and validated using ANOVA at a 95% confidence level. The models had high R2 values ranging from 95.26 to 97.74%. Multi-objective optimization was performed and validated with less than 5% error between the predicted and experimental responses.

Thickness Optimization of Thin-Film Tandem Organic Solar Cell.

The polymer solar cells also known as organic solar cells (OSCs) have drawn attention due to their cynosure in industrial manufacturing because of their promising properties such as low weight, highly flexible, and low-cost production. However, low η restricts the utilization of OSCs for potential applications such as low-cost energy harvesting devices. In this paper, OSCs structure based on a triple-junction tandem scheme is reported with three different absorber materials to enhance the absorption of photons which in turn improves the η, as well as its correlating performance parameters. The investigated structure gives the higher value of η = 14.33% with Jsc = 16.87 (mA/m2), Voc = 1.0 (V), and FF = 84.97% by utilizing a stack of three different absorber layers with different band energies. The proposed structure was tested under 1.5 (AM) with 1 sun (W/m2). The impact of the top, middle, and bottom subcells' thickness on η was analyzed with a terse to find the optimum thickness for three subcells to extract high η. The optimized structure was then tested with different electrode combinations, and the highest η was recorded with FTO/Ag. Moreover, the effect of upsurge temperature was also demonstrated on the investigated schematic, and it was observed that the upsurge temperature affects the photovoltaic (PV) parameters of the optimized cell and η decreases from 14.33% to 11.40% when the temperature of the device rises from 300 to 400 K.

Barriers of Occupational Safety Implementation in Infrastructure Projects: Gaza Strip Case.

Infrastructure projects are the foundation for essential public services and have an influential position in societal development. Although the role of infrastructure projects is substantial, they can involve complexities and safety issues that lead to an unsafe environment, and which impacts the project key stakeholders. Therefore, this study aimed to evaluate the barriers to implementing occupational safety in infrastructure projects in the Gaza Strip, which cause serious threats and reduce project performance. To evaluate the barriers, 39 items were highlighted and modified as per the construction context and environment, and which later were distributed in the form of a questionnaire, to get feedback from consultants and contractors. The analysis shows that in the safety policy barriers group, consultants and contractors both ranked the item "a contractor committed to an occupational safety program is not rewarded" first. In the management barriers group, consultants and contractors both ranked the item "safety engineer does not have significant powers, such as stopping work when needed" in the first place. In the behavior and culture barriers group, consultants and contractors both ranked the item "workers who are not committed to occupational safety are not excluded" in the first place. Overall, both consultants and contractors shared the same viewpoint in classifying the barriers in the working environment. The outcome of this study is beneficial for Palestinian construction industry policymakers, so they can monitor the highlighted barriers in on-going infrastructure projects and can modify the safety guidelines accordingly.