CivilEng, Volume 4, Issue 1 (March 2023) – 20 articles

The mathematical study known as queueing theory has recently become a major point of interest for many government agencies and private companies for increasing efficiency. One such application is vehicle queueing at an international port-of-entry (POE). When queueing, fumes from idling vehicles negatively affect the overall health and well-being of the community, especially the U.S. Customs and Border Protection (CBP) agents that work at the POEs. As such, there is a need to analyze and optimize the border crossing queuing operations to minimize wait times and number of vehicles in the queue and, thus, reduce the vehicle emissions. For this research, the U.S.–Mexico POE located at The Gateway International Bridge in Brownsville, Texas, is used as a case study. Due to data privacy concerns, the hourly wait times for vehicles arriving at the border had to be extracted manually each day using a live wait time tracker online. The data extraction was performed for the month of March 2022. Using these wait times, a queueing simulation software, SIMIO, was used to develop an interactive simulation model and calibrate the service rates. The output from the SIMIO model was then used to develop an artificial neural network (ANN) to predict hourly particulate matter content with an R² of 0.402. From the ANN, a predictive equation has been developed, which may be used by CBP to make operational decisions and improve the overall efficiency of this POE. Thus, lowering the average wait times and the emissions from idling vehicles in the queue. Full article

Tensile strength is a crucial property for the function, safety and durability of all concrete structures. The general procedure to assess the tensile properties of concrete from existing structures is to perform indirect tests and predict the tensile strength based on established empirical relationships. In this study, the direct tensile strength of concrete was investigated using cylindrical specimens. The aim of the study was to propose, test and evaluate a general method for direct tensile tests of concrete from existing structures. A total of 16 specimens were tested under deformation-controlled tensile-loading until failure. The concrete samples were prepared with 10 or 15 mm grooves at mid-height to obtain cracking in the groove region, where the crack-opening sensors were installed. The load and corresponding deformation were recorded continuously during the test to obtain the load–crack-width relationship of the concrete. The tests showed that the method can be used to assess the tensile properties of concrete from existing structures. The study provides important insights regarding the assessment of direct tensile strength of concrete and the results can be used to improve the structural health monitoring of existing structures and thereby ensure their safety and durability. Full article

This paper is aimed at serving the needs of structural engineering researchers who are seeking accelerograms that realistically represent the time histories of earthquake ground in support of their own investigations. Every record is identified with a specific earthquake scenario defined by the magnitude–distance combination and site conditions; the intensity of the presented records is consistent with ultimate limit state design requirements for important structures in an intraplate region. Presented in this article are accelerograms that were generated on the soil surface of two example class C_e sites and two example class D_e sites based on site response analyses of the respective soil column models utilizing bedrock excitations as derived from the conditional mean spectrum (CMS) methodology. The CMS that were developed on rock sites were based on matching with the code spectrum model stipulated by the Australian standard for seismic actions for class B_e sites at reference periods of 0.2, 0.5, 1 and 2 s for return periods ranging from 500 to 2500 years. The reference to Australian regulatory documents does not preclude the adoption of the presented materials for engineering applications outside Australia. To reduce modeling uncertainties, the simulation of the soil surface ground motion is specific to the site of interest and is based on information provided by the borelogs. The site-specific simulation of the strong motion is separate to the CMS-based accelerogram selection–scaling for obtaining the bedrock accelerograms (utilizing strong motion data provided by the PEER). The decoupling of the two processes is a departure from the use of the code site response spectrum models and has the merit of reducing modeling uncertainties and achieving more realistic representation of the seismic actions. Full article

Reinforced concrete (RC) core walls are commonly used to provide buildings with lateral and torsional resistance against the actions of wind and earthquakes. In low-to-moderate seismic regions, it is not unusual to find a single peripheral core wall that alone should resist these actions, where the torsional (rotational) twist cannot be neglected. It has previously been difficult to have confidence in simulating the axial-flexure-torsion behavior of these RC core walls, primarily due to: (i) some types of modelling approaches being unable to appropriately account for the shear-flexural action, as well as torsional response; and (ii) the scarcity of experimental data, particularly for walls under torsional loads, which would be required to validate such models. In this research, beam-truss models (BTMs), which correspond to an interesting compromise between detailed modelling and practical applications, were used to simulate the in-plane and diagonal flexural response of RC U-shaped walls. Furthermore, the global torque-rotation results from a recent experimental wall test provided the evidence to further validate this powerful modelling technique. A case study building, comprising an RC U-shaped core wall structure with varying eccentricity values, was evaluated for an earthquake event with a 2475-year return period in the city of Melbourne, Australia, using the capacity spectrum method. Nonlinear static pushover analyses showed that, depending on the magnitude of torsion, the in-plane flexural strength and displacement capacity can be significantly reduced. The results from this research emphasize the importance of including torsional actions in the design and assessment of reinforced concrete buildings. Full article

This paper aims to show the application of site-specific response spectra in the analysis of buildings that are supported by lightly reinforced precast concrete walls. Previous surveys on load-bearing precast reinforced concrete walls in multi-storey buildings in low-to-moderate seismic regions have found that many existing precast walls are lightly reinforced with a connection reinforcement ratio less than the wall reinforcement ratio. When these precast walls are subjected to reversed cyclic loads, the lateral response is typically controlled by rocking and the ultimate performance is governed by the ruptures of connection dowels. This paper uses moment–curvature analyses in combination with plastic hinge analyses to evaluate the force–displacement capacity of planar lightly reinforced load-bearing precast walls. The seismic performance of a building supported by these lightly reinforced precast walls can then be assessed by superimposing the capacity curve and the inelastic site-specific response spectra developed for the building site. The proposed analytical approach is illustrated through a case study building. By comparing a lightly reinforced precast wall with a comparable limited ductile reinforced concrete wall, it is also found that, although these two walls exhibit similar force capacities, the ultimate displacement capacity of the lightly reinforced precast wall is significantly lower. This finding highlights the potential seismic vulnerability of lightly reinforced precast walls in some existing buildings. Full article

This paper aims at giving structural designers guidance on how to transform seismic demand on a building structure from two-dimensional (2D) to three-dimensional (3D) in an expedient manner, taking into account amplification of the torsional actions. This paper is to be read in conjunction with either paper #3 or #4. Torsional amplification of the drift demand in a building is of major concern in the structural design for countering seismic actions on the building. Code-based seismic design procedures based on elastic analyses may understate torsional actions in a plan of asymmetric building. This is because the inability of elastic analyses to capture the abrupt increase in the torsional action as the limit of yield of the supporting structural walls is surpassed. Nonlinear dynamic analysis can provide accurate assessment of torsional actions in a building which has been excited to respond in the inelastic range. However, a 3D whole building analysis of a multi-storey building can be costly and challenging, and hence not suited to day-to-day structural design. To simplify the analysis and reduce the scale of the computation, closed-form expressions are introduced in this paper for estimation of the ${\mathsf{\Delta }}_{3D}/{\mathsf{\Delta }}_{2D}$ drift demand ratio for elastic conditions when buildings are subjected to moderate-intensity ground shaking. The drift demand of the 3D model can be estimated as a product of the 2D drift demand and the ${\mathsf{\Delta }}_{3D}/{\mathsf{\Delta }}_{2D}$ drift demand ratio. In dealing with higher-intensity ground shaking causing yielding to occur, a macroscopic modelling methodology may be employed. The estimated ${\mathsf{\Delta }}_{3D}/{\mathsf{\Delta }}_{2D}$ drift demand ratio of an equivalent single-storey building is combined with separate analysis for determination of the 2D drift demand. The deflection profile of the multi-storey prototype taking into account 3D effects, including torsional actions, is hence obtained. The accuracy of the presented methodologies has been verified by case studies in which drift estimates generated by the proposed calculation procedure were compared against results from whole building analyses, employing a well-established computer software. Full article

The penetration of ions plays an important role in the durability of concrete structures. This study aims to establish the feasibility of using dental X-ray equipment to measure the concentration and penetration of iodide within cementitious systems. This technique is known as checking ion penetration (CHIP). This test uses iodide as a tracer because it has a high electron density, and so it can be observed with X-ray imaging as it penetrates the concrete. Concentration profiles from CHIP are used to calculate the apparent diffusion coefficient (D_ac). These results are similar to measurements from bulk chloride ponding tests. The D_ac is used to predict the service life or evaluate the quality of an as-built concrete structure or concrete mixture. Because of the wide availability of dental equipment, CHIP shows promise to be used as a method to measure the in-place quality control of the concrete. Full article

The construction industry holds the worst safety record compared to other industrial sectors, and approximately 88% of accidents result in worker injury. Meanwhile, after the development and wide application of deep learning in recent years, image processing has greatly improved the accuracy of human motion detection. However, owing to equipment limitations, it is difficult to effectively improve depth-related problems. Wearable devices have also become popular recently, but because construction workers generally work outdoors, the variable environment makes the application of wearable devices more difficult. Therefore, reducing the burden on workers while stabilizing the detection accuracy is also an issue that needs to be considered. In this paper, an integrated sensor fusion method is proposed for the hazard prevention of construction workers. First, a new approach, called selective depth inspection (SDI), was proposed. This approach adds preprocessing and imaging assistance to the ordinary depth map optimization, thereby significantly improving the calculation efficiency and accuracy. Second, a multi-sensor-based motion recognition system for construction sites was proposed, which combines different kinds of signals to analyze and correct the movement of workers on the site, to improve the detection accuracy and efficiency of the specific body motions at construction sites. Full article

The durability of concrete structures is essential for reliable infrastructure. Although many deterioration models are available, they are rarely applied in situ. For existing structures in need of repair or durability assessment, this is also the case for Building Information Modeling (BIM). However, both BIM and durability modeling hold great potential to both minimize expended resources and maximize the reliability of structures. At the Institute for Building Materials Research (ibac) at RWTH Aachen University, a novel approach to the calibration of deterioration models using Bayesian inference iteratively in a BIM model enriched with machine-readable diagnosis data to achieve a predictive decision support tool is being developed. This paper demonstrates the digital workflow, validates the proposed approach, and expresses the added value for the planning of repair measures. Full article

One of the most common pavement distresses in flexible pavement is rutting, which is mainly caused by heavy wheel load and various other factors. The prediction of rutting depth is important for safe travel and the long-term performance of pavements. Factors that are considered in this paper for the prediction of rut depth are Temperature, Equivalent Single Axle Load, Resilient modulus, and Thickness of hot mixed asphalt. The input data for all factors are collected from the Long-Term Pavement Performance Information Management System for the state of Texas. Regression analysis is performed for dependent and independent variables to obtain the empirical relationship. In various fields of civil engineering, artificial neural networks have recently been utilized to model the qualities and behavior of materials and to determine the complicated relationship between various properties. An Artificial Neural Network is used to develop a predictive model to predict the rutting depth. A total number of 70 observations were considered for the predictive model. A mathematical relation is developed and verified between rut depth and variable input data. Full article

During the first filling, the reservoir is gradually raised in multiple stages. At each stage, the filling is paused to allow adequate time for monitoring and evaluating the performance of the dam and its foundation. The analysis of the monitored behavior and assessment of security conditions is performed by comparing the values measured by the monitoring system installed in the dam with the values predicted by numerical models representing the structural behavior, the material properties, and the loads. This article addresses the main aspects related to the safety control of concrete arch dams during the first filling of the reservoir. Special attention is given to the nonlinear behavior induced by the opening/closing of the contraction joints. An example of numerical simulation of the behavior of an arch dam during the first filling of the reservoir is also presented. The validation of the computed temperatures, the induced displacements and the induced stresses was performed by comparison with the values measured with the monitoring system installed in the dam. Full article

This paper is aimed at giving structural designers guidance on how to make use of elastic site-specific response spectra for the dynamic modal analysis of a structure in support of its structural design. The use of response spectra in support of the pushover analysis of an RC building forming part of the non-linear static analysis procedure (that can be used to predict seismic demand without relying on the code-stipulated default R factor) is also presented. Seismic analysis of structures based on the use of site-specific response spectra can help to achieve a more optimised, and cost-effective, structural design compared to the conventional approach employing a response spectrum model stipulated by the code for different site classes. Currently, the methodology is only adopted in major projects in which enough resources are available to engage experts who are skilled in operating the procedure; thus, the use of site-specific response spectra in structural engineering practice is still limited despite the merits of the procedure. Deriving a site-specific response spectrum requires a database of representative ground motion records to be developed. Extra analytical tasks to be undertaken include the processing of bore log data, site response analyses, and selection/scaling of bedrock accelerograms for input into site response analyses. Guidelines for implementing this design methodology are currently lacking. To promote the wide adoption of site-specific seismic design, this article presents the procedure for developing the required site-specific design spectra, as well as guidelines for applying these spectra for seismic design based on analyses of linear, or nonlinear, models of the building. Non-linear analysis can be accomplished by dealing with macroscopic models as illustrated in a case study. Full article

This study presents finite element analysis of double split tee (DST) connections with high-strength steel bolts and coupled split tee sections, to evaluate various cyclic response parameters and elements. The investigation included quantifying connection behavior and hysteretic response, damage indexes, and failure modes. Over 40 specimens were simulated in ABAQUS under cyclic loading, including shape memory alloy (SMA)-built specimens. In the post-analysis phase, the T-stub thickness, the T-stub yield strength, the bolt preload and bolt number, and the stiffener type and stiffener material for the most significant parts of the DST connection were calculated. Simulation results showed that a lower ultimate moment yielded fewer needed stem bolts. The energy dissipation (ED) capacity increased as the horizontal distance between the stem bolts decreased. Additionally, increasing the strength of the bolt and T-stub by 15% resulted in a 3.86% increase in residual displacement (RD) for the bolt and a 1.73% decrease in residual displacement for the T-stub. T-stub stiffeners enhanced ED capacity by 31.7%. SMA materials were vulnerable to mode 1 failure when used in T-stubs, bolts, or stiffeners. However, the use of SMA increased the rate of energy dissipation. Adding stiffeners to the T-stubs altered the failure indexes and improved the pattern of failure modes. In addition, stiffeners decreased the rupture and pressure indexes. As a result, the failure index of a T-stub shifted from brittle failure to ductile failure. Full article

The application of Accelerated Bridge Construction methods (ABC) to build, renovate and rehabilitate aging bridges is most likely to reduce the economic and social impacts of projects. This is especially relevant in countries with severe winter climates, where bridge construction is typically interrupted during the winter period. The objective of this study is to present the state of the art related to elements, systems, connections and materials used for bridge superstructures in ABC projects and to highlight their adaptability to cold or northern climate countries. The literature review and presentation of results are based on the gathering of Prefabricated/Precast Bridge Elements and Systems (PBES) used for ABC projects in North America and which are also used in many countries around the world. Following this inventory, and after grouping the PBES, connections and materials, the authors were able to identify the possibility of adapting the ABC method for countries with cold and northern climates. Products that can be used down to −6 °C for connections are presented, and future research orientations are proposed. Full article

The present research deals with the cyclic and standard pull-out resistance of deformed steel bars embedded in lightweight and normal concrete. This paper is a continuation of a previous paper, where the experimental results are detailed. In the present paper, the experimental results are set against the formulas and the diagrams provided by the Eurocode standard and the Model Code 1990, and then a comparative discussion is performed. In the case of cyclic loading, the damage defined by the Palmgren–Miner hypothesis, as well based on the recommendations of various national annexes of Eurocode and the Model Code, is calculated. A multiplier corresponding to the maximum load is calculated, which indicates by how much the applied load should be multiplied to obtain a damage value equal to 1. Full article

This study discusses the torsional capacity of recycled coarse aggregate (RCA) reinforced concrete beams under pure torsion based on the experimental findings available in the literature. The experimental data on RCA specimens were collected and compared with the conventional concrete specimens with key variables, such as compressive strength and longitudinal and transverse reinforcement ratios, as those variables affect the torsional capacity of reinforced concrete beams. Overall, the database consisted of experimental results from 30 RCA specimens and 256 natural coarse aggregate (NCA) specimens. The result shows that specimens with a 100 % replacement ratio have the lowest strength. In addition, as the structural mechanism of torsion is similar to the shear mechanism in reinforced concrete beams, a comparative analysis was performed with RCA specimens subjected to shear force. It was concluded that the RCA has a similar effect in strength reduction for the specimens subjected to torsion or shear with a 100% replacement ratio. However, further study and experimental evidence are required to confirm the applicability of the recycled aggregate to produce and design the structural members. Full article

Nowadays, due to environmental changes, the condition of buildings can be in danger. In order to protect the performance of existing buildings, it is important to investigate the seismic behaviour of building structure subjected to earthquake excitation. In addition, it is important to study the advanced level of ductile design recommended by current codes. In the immediate future, lateral load resistance needs to be evaluated precisely. For the purpose of analyzing the seismic responses of reinforced concrete (RC) buildings in this project, 6- and 12-story frames of representative buildings are modeled in this research paper. The response spectrum analysis is deployed for a multi-degree-of-freedom system exposed to seismic waves (earthquake) in the City of Vancouver. Hence, the seismic nature of Vancouver City is emulated by the resulting response spectra using ground motion records (GMR). Ultimately, for concluding the average displacement as well as the base shear of the structures, a time-history analysis is investigated. In this regard, the SAP2000 and ETABS software are utilized for analyzing seismic performances. In addition, a comparison is presented between previous studies that used the IDARC2D software and the proposed results that used the ETABS software. It is found that the applied cases are not overlapping the limit of the NBCC 2015 Code. Consequently, after investigation, it is evident that the 3D software is much more accurate than the 2D software. Full article

This study models concrete as a multi-phase system that comprises the mortar, coarse aggregates, and interfacial transition zones (ITZs). The diffusivity and the volumetric fraction of these phases are considered to propose a three-phase diffusion–reaction model to simulate the external sulphate attack. Furthermore, the parametric analysis alongside the sensitivity analysis is carried out to quantify the effect of these phases on the expansive cracking in concrete when exposed to a sulphate-rich environment. The results show that mortar dominates the sulphate ingress and the ensuing distress, while the ITZ is found to be least significant. Due to its significantly low permeability, the coarse aggregate may act as a “deceleration strip” or a “dam”, which in turn obstructs the sulphate penetration. More importantly, this effect is further noted to evolve with a decrease in the diffusivity and a rise in the volumetric fraction of coarse aggregates. As for ITZ, its volume fraction may play a more dominant role than its diffusivity on sulphate attack in concrete. Full article

This study presents analysis of two types of experimental test related to the crack propagation in concrete specimens subjected to high-sustained loading levels and quasi-static loadings. The concept of the equivalent crack length is introduced to perform this analysis. Even though this analysis is partial, it shows the influence of loading rate conditions on the crack process rate. This result shows that, in the domains of low and very low loading rates, the concrete mechanical characteristics linked to the cracking process (for example, tensile strength, post-cracking behaviour, etc.) are dependent on the loading rates applied to the specimens for determining them. Full article