CivilEng, Volume 3, Issue 3 (September 2022) – 15 articles

Previous work has shown that floor slabs make up most of the material mass of building structures and are typically made of reinforced concrete. Considering the associated resource consumption and greenhouse gas emissions, new approaches are needed in order to reduce the built environment’s impact on the ongoing climate crisis. Various studies have demonstrated that adaptive building structures offer a potential solution for reducing material resource consumption and associated emissions. Adaptive structures have the ability to improve load-bearing performance by specifically reacting to external loads. This work applies the concept of adaptive structures to reinforced concrete slabs through the integration of fluidic actuators into the cross-section. The optimal integration of actuators in reinforced concrete slabs is a challenging interdisciplinary design problem that involves many parameters. In this work, actuation influence matrices are extended to slabs and used as an analysis and evaluation tool for deriving actuation concepts for adaptive slabs with integrated fluidic actuators. To define requirements for the actuator concept, a new procedure for the selection of actuation modes, actuator placement and the computation of actuation forces is developed. This method can also be employed to compute the required number of active elements for a given load case. The new method is highlighted in a case study of a 2 m × 2 m floor. Full article

Bridges often have complicated geometries in complex terrain where they can be exposed to high wind loading. Current practice in designing for wind can be conservative. The drive for more lean construction motivates the study of computational modelling as an alternative to traditional methods of determining these wind loads. This paper compares wind forces determined using Eurocode 1 Part 4 with those determined by CFD modelling for a given bridge geometry, taking variations in altitude, location, wind speed and wind direction into account. Results indicate that the exposure factors used in Eurocode 1 Part 4 inflate the net wind force values. It was also found that the directional factor is conservative for wind forces on bridge decks but ineffective for wind forces on bridge piers in the x-direction. Furthermore, the Reynolds-Averaged Navier–Stokes equations (CFD) appear to produce smaller values of net wind force than Bernoulli’s equation (Eurocode). Bernoulli’s equation can only be applied to an ideal fluid, and Reynolds-Averaged Navier–Stokes equations can be applied to any viscous fluid—a further concern with the current practice. Full article

The discussion of project success has expanded beyond project management and success criteria. The main cause of the failure to evaluate project performance in construction projects is the absence of a shared definition and a common set of criteria for project success. The aim of this paper is to develop a framework which includes certain success criteria to assess construction projects and allows for the calculation of a Project Success Score (PSS). The Rapid Impact Assessment Matrix (RIAM) approach is adopted and modified appropriately, providing a framework that combines primary and secondary success criteria to compute a comprehensive Project Success Score (PSS). Seventeen (17) success criteria are included in the framework, and their corresponding thresholds are formulated to determine the limits of failure of a project. The final PSS consists of five distinct classes, which range from the level of absolute success (PSS in the range of 9361 to 13,500) to the level of absolute failure (13 to 384). Finally, a web application that simulates the PSS framework is developed. The web application was tested by an end-user, in order to assess its applicability and ease of use, and the facilitation of the whole computation process of PSS was ensured. This paper provides a rational framework through which construction projects can be rapidly assessed, with the aim of highlighting the potential unsuccessful criteria in each project and increasing the probability of more effective project outcomes. Full article

The adverse environmental impacts of building materials can be achieved by reducing the amount of cement in cementitious composites, specifically when incorporating wastes as partial replacement for Portland cement. In this work, we substitute cement with shell by-products while keeping useful specific properties. Scallop shells are good candidates to replace part of the Portland cement as they contain calcium and are available in abundance. We present an experimental and numerical study on the mechanics, hygrothermal behavior, and life cycle analysis of scallop shell concrete. In the fresh state, the replacement of cement by up to 10 wt.% of scallop shells does not significantly affect mortar properties. The results indicate that including 10% shells represents a decrease of up to 40% in the environmental impact, depending on the category of impact considered. Furthermore, the addition of Scallop shells makes the material more porous, leading to the facilitation of moisture transfer. Full article

Lignosulfonate-based admixtures (LS) obtained from sulfite pulping processes were the first dispersants added as a water-reducer to concrete. Less effective than the latest superplasticizers, the low cost and low environmental footprint of LS continue to allow these materials to compete in the building and construction market. In addition to the dispersion effect, LS is known to retard cement hydration. The aim of this paper is to characterize the effect of LS on the hydration and rheology of cement paste. The effect of the time at which the LS is added, either by immediate addition or after ten minutes of hydration, has been investigated. It appears that the immediate addition of LS is less effective than the delayed addition when it comes to dispersion of cement, likely due to the initial ettringite formation. Full article

The main objective of this study was to investigate the characteristic properties of lignin-modified bitumen with different lignin contents. The first step was the characterization of the physicochemical and thermal properties of the kraft lignin powder along with the determination of its microstructure. This was achieved by carrying out an elemental analysis, Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA)/Derivative Thermogravimetry (DTG), Fourier Transformation Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS) and Confocal Microscopy. After the latter tests, three (3) blends with different lignin contents (5%, 10% and 15% by weight of bitumen) were produced. Characteristic properties such as penetration, softening point, elastic recovery, force ductility, dynamic viscosity and storage stability were determined for the reference bitumen and the three lignin blends. The main conclusion was that kraft lignin powder hardens the conventional bitumen. Specifically, the addition of 15% lignin to the bitumen hardened the blend to such a degree that the bitumen changed category from 50/70 to 35/50 with respect to EN 12591. Full article

In structural sizing optimization problems, the number of design variables typically used is relatively small. The aim of this work is to facilitate the use of large numbers of design variables in such problems, in order to enrich the set of available design options and offer the potential of achieving lower-cost optimal designs. For this purpose, the concept of cascading is employed, which allows an optimization problem to be tackled in a number of successive autonomous optimization stages. In this context, several design variable configurations are constructed, in order to utilize a different configuration at each cascade sizing optimization stage. Each new cascade stage is coupled with the previous one by initializing the new stage using the finally attained optimum design of the previous one. The first optimization stages of the cascade procedure make use of the coarsest configurations with small numbers of design variables and serve the purpose of basic design space exploration. The last stages exploit finer configurations with larger numbers of design variables and aim at fine-tuning the achieved optimal solution. The effectiveness of this sizing optimization approach is assessed using real-world aerospace and civil engineering design problems. Based on the numerical results reported herein, the proposed cascade optimization approach proves to be an effective tool for handling large numbers of design variables and the corresponding extensive design spaces in the framework of structural sizing optimization applications. Full article

The study investigates through hygrothermal modelling the effect of different boundary conditions and varying measured vapour diffusion resistivity values on the hygrothermal performance of five pliable membranes. Previously, this research quantified the variable water vapour diffusion resistivity properties of five different pliable building membranes. The membranes were assessed under varying humidity conditions using the gravimetric wet and dry cup test method. The varying humidity conditions better represent the boundary conditions experienced by materials in the building envelope. The pliable membranes include two permeable, two impermeable, and one variable products, which are commonly used to provide air and vapour control layers in the construction of framed external wall systems. This article focusses on the transient hygrothermal modelling of each of these membranes as a component of a typical timber-framed, clay brick veneer external wall system. The simulations were completed for three different climate types, namely, hot and humid, temperate, and cool-temperate with snow, and with a northern and western orientation. The results from hygrothermal and bio-hygrothermal simulations highlighted different responses subject to climate type and orientation. These results show that there are significant differences in simulated moisture and mould growth risk between the results of pliable membranes with single vapour resistance factor value and pliable membranes with multipoint vapour resistance factor values. Full article

The hazardous nature of the construction environment and current incident statistics indicate a pressing need for safety performance improvement. One potential approach is the strategic analysis of leading indicators for measuring safety performance as opposed to using only lagging indicators, which has protractedly been the norm. This study presents a systematic safety performance measurement framework and statistical modeling processes for analyzing safety incident data for accident prediction and prevention on construction sites. Using safety incident data obtained from a construction corporation that implements proactive safety management programs, statistical modeling processes are utilized to identify variables with high correlations of events and incidents that pose dangers to the safety and health of workers on construction sites. The findings of the study generated insights into the different types and impacts of incident causal factors and precursors on injuries and accidents on construction sites. One of the key contributions of this study is the promotion of proactive methods for improving safety performance on construction sites. The framework and statistical models developed in this study can be used to collect and analyze safety data to provide trends in safety performance, set improvement targets, and provide continuous feedback to enhance safety performance on construction sites. Full article

This paper describes the fundamental evaluation of a self-sensing concrete column using recycled steel residuals (RSR) as functional fill and the testing of the column under slow-rate cyclic loading. The RSR modified concrete has the advantage of sustainably using the otherwise waste material from steel fabrication process. Two columns (one without and one with 2% of RSR by volume) were fabricated in the lab and load-tested in cyclic axial compression. The columns are connected to an alternating current power source and have three electrode sets each for electric property measurements. The results indicate that the 2% specimen can accurately detect the loading and unloading processes using electric-based measurements to calculate resistivity. Based on the test results, empirical linear equations are derived to correlate the mechanical and electrical behaviors. Full article

In the UK, High Speed Rail 2, (London to the ‘North’) is surrounded by a number of questions regarding construction technologies which can minimise the impact of the route. The rail industry in the UK has vast experience based with ballasted track, but this is not necessarily the most appropriate choice for new high speed rail construction when crossing problematic soils. This paper aims to investigate the use of different track types (ballasted and ballastless) and the influence they will have on the underlying soil in areas predominated by non-engineered mudrock backfills, relics of the UK’s mining heritage. Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. Structural performance of the railway track strongly depends on the level of stress that is transmitted to the ground and this must be reduced to an acceptable level to minimise deterioration in the mudrock if they are to be utilised effectively. The main objective for this paper is to investigate the impact of the initial stress conditions and dynamic stress on the permanent deformation of mudrock under different physical conditions. Triaxial testing is used to estimate the stiffness characteristics of the mudrock. The results show that the resilient modulus increases with a decrease in the stress amplitude. In addition, ballasted track shows a higher suitability for use in design in terms of the stiffness generated within the mudrock. Full article

Cross laminated timber (CLT) is becoming increasingly popular in timber construction due to its versatility. However, its structural anistropy requires the application of particular concepts and design methods. The article on hand presents the results of a worldwide survey conducted among engineers working with this product. Thus, it presents the current state of knowledge and practice on CLT construction: an overview of the experience of engineers working with CLT design, the commonly used verification methods, and the implementation of the material properties and different required assumptions in the software. An outlook to design problems in complex design situations relevant for multi-storey buildings and potential research fields is indicated additionally. The general picture is quite heterogeneous, with little consensus on the assumptions, design methods or applied tools. A wide repertoire of different approaches based on a large range of literature is found in practice. This is in part the result of the current lack of standardisation and currently incomplete regulations. Future efforts should focus on these two aspects to increase the applicability of CLT globally and strengthen its competitiveness. Full article

This study investigates the field performance of Warm Mix Asphalt (WMA) road overlays containing various amounts of RAP and binder. Rutting, the International Roughness Index (IRI), and transverse, longitudinal and alligator cracking are the key parameters considered here. Our research is based on a Specific Pavement Study-10 experiment (SPS-10) conducted in nine states of North America (eight in the USA and one in Canada) that included 31 road sections in dry and wet regions. Road overlays were evaluated 1 and 4 years after their placement in terms of anti-cracking behavior and were compared with the pre-treatment status of the road. The best rutting resistance occurred at 15% and 12% RAP in dry and wet regions, respectively. For IRI, 30% and 0.0% RAP were the best for dry and wet regions as well. The maximum longitudinal crack recovery rates were found at site 3 (BA01, Arizona; dry region) and site 26 (AA65, Missouri; wet region), with RAP contents of 20% and 36%, respectively. In addition, alligator cracking did not occur post-overlay, so optimal RAP and binder contents cannot be suggested. The greatest improvements were found at site 15 (AA01, Washington state; dry) and site 30 (AA63, Oklahoma; wet). The response surface method (RSM) was also developed to explore the optimal models for RAP and selection of binder contents to minimize the rutting, IRI, and transverse and longitudinal crack lengths. Full article

Pile foundation is an effective technique to support buildings in the presence of soft soil and seismic areas. More recently, the rigid inclusions system has also been utilized for founding buildings. Both systems increase the bearing capacity of the soil and allow reducing the total and differential settlements in the structure. However, the study of these systems in a complete and accurate way implies the consideration of the soil–structure interaction (SSI). In order to investigate the impact of different pile toe conditions (including the placement on hard soil, an anchorage and floating piles) in the response of mid-rise buildings, numerical models with a 5-storey frame building founded on the inclusions system (soil–inclusion–platform–structure) are analyzed and compared with the pile system (soil–pile–structure). Fully coupled finite difference numerical models were developed using Flac 3D. The influence of the dynamic characteristics of the structure was considered analyzing buildings with different heights (3 storeys to 7 storeys). The linear elastic perfectly plastic model with a Mohr–Coulomb failure criterion is used to represent the behavior of the soil. Values of the maximum lateral displacements, of the inter-storey drifts and of the shear forces distribution in the buildings, as well as the rocking of the foundation, are presented. Concerning the foundations, efforts and displacements are compared for the different systems. The results show that the type of support condition influences the seismic response of the building and the efforts and displacements in the rigid elements, depending on the foundation system. The efforts at the toe level in the rigid elements are highly influenced by the support conditions, but there is only a slight influence from the head connection. Full article

Polypropylene fiber reinforced concrete (PFRC) is becoming more popular for structural purposes due to its durability, electrical resistivity, and mechanical properties. In this study, the influence of polypropylene fiber on the mechanical properties and ultrasonic pulse velocity (UPV) of fiber reinforced concrete (FRC) were determined. Six different fiber volume fractions of polypropylene were considered in the experimental investigation with varying water–cement ratios and curing conditions. Non-destructive testing methods were utilized to determine the UPV of the PFRC. Available equations in literature for predicting the RFC’s compressive strength based on UPV values were selected. However, the computed values did not show good agreement with the compressive strengths obtained from the compression testing machine. It was confirmed that polypropylene fibers alter the propagation of UPV, and as a result, the existing equations do not accurately predict the compressive strength for PFRC. Therefore, a practical equation is proposed to accurately evaluate the compressive strength of PFRC with regard to UPV. Full article