Modern Civil Engineering Research Articles

Enhancing operational performance assessment of structures with seismic response modification devices: The role of observability and symmetry analysis under limited sensor deployment

AbstractTo manage structural responses under various external forces, the increasing incorporation of seismic isolation and supplementary damping systems in modern civil engineering necessitates post‐installation performance assessments. The challenge of accurately inferring system information from these complex dynamical structures, especially with limited sensor deployment, could be significant. From the perspective of solving inverse problems, this challenge hinges on constructing an input‐output mapping that assures unique solutions, achievable through theoretical observability or symmetry analysis. We introduce a unified algorithm framework designed to accommodate various definitions of Lie derivatives, specifically for observability and symmetry analysis in dynamic systems with affine, non‐affine, and unknown inputs—capabilities not fully achieved in previous studies. We demonstrate its application across typical dynamic scenarios, including both linear and nonlinear examples. We also present a numerical example featuring complex isolation systems with limited sensor layouts, illustrating how uniform convergence can be achieved in estimating all system states when an observable input‐output mapping is utilized. Furthermore, an experimental example employing shaking table tests showcases the potential complications that arise when an unobservable input‐output mapping is used.

A lightweight concrete composite material with improved EMI shielding by using a chiral particle array

This paper proposes a structure for concrete composite materials for electromagnetic interference shielding applications. It comprises an array of helical-shaped conductive particles as chiral additives. Unlike the previous studies using large quantities of conductive additives, this study provides a lightweight concrete composite due to the utilization of a small number of additives with a high level of shielding effectiveness in a wide frequency range. The heart of the proposed structure lies in leveraging the evanescent wave propagation in a circular waveguide, resulting in considerable shielding effectiveness. Under particular conditions, the helical particles can imitate a below-cutoff cylindrical waveguide and its dominant mode surface current on the helical wire. This phenomenon significantly attenuates the transmitted power from the array of helical particles in its resonance frequency range. Besides presenting the composition that exploits the magnetoelectric properties of the particles, this paper compares it with a traditional concrete composite, including randomly distributed sinusoidal steel rods. This second approach is examined using both experimental measurement and full-wave simulation methods. The results of this study indicate that the appropriate geometry of the conductive additives, in this case, chiral particles, and their arrangement in a regular array rather than a random distribution can enhance the efficiency of the conductive additives. This idea paves the way for more robust, efficient, and lightweight concrete composite materials, thanks to the recent advances in modern civil engineering manufacturing methods.

Exploring a cellulose-immobilized bacteria for self-healing concrete via microbe-induced calcium carbonate precipitation

Concrete is widely used in modern civil engineering due to its high compressive strength, abundance of raw materials, and simple production process. However, its brittleness makes it vulnerable to environmental factors, leading to cracks that impact its durability. Microbial-induced carbonate precipitation (MICP) technology has emerged as a promising solution, offering environmental benefits, real-time repair capabilities, and reduced manual intervention. This study focuses on enhancing the efficiency of calcium sources by identifying a strain with calcium ion adsorption abilities and pairing it with a mineralizing bacterium rich in urease production. Microorganisms were immobilized in a microcapsule using a cellulose-based material to explore the potential of cellulosic gel as a bacterial carrier. The gel was prepared through a sol-gel transformation process, incorporating a porogen to create a porous structure. Microcapsules with a particle size of 2.5–3.0 mm were successfully produced, enhancing their mechanical strength by 88.29 %. Examination of the microscopic structure of the cellulosic gel demonstrated its strong immobilization capacity for bacterial spores. The self-repairing effect of the gel on cracks was particularly effective under water curing conditions at 30–40 °C. After 28 days, cracks up to 0.3 mm wide were repaired, with a repair rate exceeding 90 % for cracks 0.1–0.2 mm wide.

A deep transfer learning-based algorithm for concrete surface defect detection

The integrity and safety of concrete structures are crucial in modern civil engineering. Traditional image-defect detection methods are significantly affected by light and noise. Methods based on deep learning, particularly convolutional neural networks (CNNs), offer new solutions for automated defect detection. This paper introduces a concrete surface defect detection algorithm based on deep transfer learning. Our model utilizes the ResNet50 architecture as its backbone and incorporates Atrous Spatial Pyramid Pooling (ASPP) to adapt to the diversity of defects and enhance recognition accuracy. In addition, the use of a self-attention mechanism effectively enhances the model’s focus on and analysis of key defect areas, improving its ability to perceive and select features for defects of various sizes, aiding precise localization and classification under complex conditions. Image preprocessing techniques such as resizing, conversion to grayscale, histogram equalization, and noise addition further enhance the robustness of the model in diverse real-world scenarios. On the publicly available COncrete DEfect BRidge IMage Dataset, our model achieved a mean average precision (mAP@0.5) of 0.90, showing a 3.4% improvement over the current best baseline method. Through transfer learning, it reached 0.92 on our custom dataset, significantly outperforming existing methods. These results demonstrate the effectiveness and superiority of the proposed model for detecting concrete defects. Additionally, we evaluated the impact of different architectures on model performance. Compared to traditional models using the VGG16 as the backbone, the ResNet50 architecture used in this study reduces parameter count by 5.41 times while improving performance by 6.1%.

Pelatihan dan Sosialisasi Penggunaan Aplikasi Perhitungan Struktur Gedung (SAP2000)

The advancement of modern civil engineering, software designed to facilitate and expedite the structural analysis calculation process, especially for seismic analysis, is also becoming increasingly sophisticated. The presence of this software greatly facilitates civil engineers in conducting analyses. Conducting seismic analysis for tall buildings using hand calculations not only consumes a significant amount of time and effort but also increases the risk of calculation errors due to human error. Training and Socialization on the Use of Building Structure Calculation Applications (SAP2000) were conducted offline in the Computer Laboratory Room of the MRK Civil Engineering Department, Faculty of Engineering, Syiah Kuala University. In general, the training and socialization materials on the use of building structure calculation applications, included an Introduction to Application Features, Modeling Steps, Continuous Beam Modeling Tutorial, 2D Frame Modeling Tutorial, and 3D Frame Modeling Tutorial. Based on the monitoring during the training, the participants showed great enthusiasm. They highly appreciated this activity as it provided them with the opportunity to learn about building structure calculations, and there were requests for further training sessions. After the completion of the activity, the participants were asked to fill out a questionnaire regarding the effects of using the application. One of the questions asked was about the participants' understanding after the training, where 100% of the participants reported an improvement in understanding due to the training activities.

Structural and Economical Analysis of Cable-Stayed Bridges

Abstract: Cable-stayed bridges have emerged as prominent structures in modern civil engineering, renowned for their aesthetic appeal, structural efficiency, and economic viability. This review paper provides a comprehensive analysis of the structural and economic aspects of cable-stayed bridges. It encompasses a thorough examination of various design considerations, construction techniques, material selection, and economic factors influencing the feasibility and performance of cable-stayed bridges. Through the synthesis of existing literature and case studies, this paper aims to offer insights into the key factors driving the design, construction, and economic evaluation of cable-stayed bridges, thereby aiding engineers, planners, and decision-makers in making informed choices in bridge infrastructure development projects.

Application of High-performance Concrete in Civil Engineering

With the continuous improvement of modern civil engineering performance requirements on building materials, high-performance concrete (High-Performance Concrete, HPC) has become one of the key materials. This paper discusses the application of HPC in various civil engineering, and its innovative impact. HPC has played a key role in many major engineering projects for its extraordinary durability, high intensity and excellent working nature. First, the paper introduces the basic composition and performance characteristics of HPC, including its compressive strength, durability and rheological properties. The optimized formulation of HPC reduces the use of cement, and cement production is one of the major sources of carbon emissions. By using fly ash, silicon ash and other industrial by-products to replace part of the cement components, HPC not only improves its environmental friendliness, but also enhances the comprehensive performance of the material. Finally, the paper prospects the potential development of HPC in future civil engineering. With technological advances and increasing demand for environmentally friendly building materials, the improvement and application of HPC will continue to expand.

Influence of Dilution on the Mechanical Properties and Microstructure of Polyurethane-Cement Based Composite Surface Coating.

Polyurethane-cement composite are widely used in modern civil engineering, and the method of adding diluent is often used to adjust the construction process to adapt to the engineering environment. Studies have shown that the addition of diluent impacts the performance of polyurethane-cement based composite surface coatings, but there have been few reports on the influence of diluent content on the mechanical properties and microstructure of the coatings. To address this, polyurethane coatings with different diluent contents were prepared, and positron annihilation lifetime spectroscopy was used to test the microstructure of the coatings. The tensile strength and elongation at rupture were tested using a universal material testing machine, and the fracture interface morphology of each coating was observed by scanning electron microscopy. Finally, the correlation between the microstructure parameters and the mechanical properties of the coating was analyzed using grey relation theory. The results demonstrated that with the increase in diluent content, (i) the average radius of the free volume hole (R) and the free volume fraction (FV) of the coating both showed a trend of first decreasing and then increasing. The value of R was between 3.04 and 3.24 Å, and the value of FV was between 2.08 and 2.84%. (ii) The tensile strength of the coating increased first and then decreased, while the elongation at rupture decreased first and then increased. Among them, the value of tensile strength was between 3.23 and 4.02 MPa, and the value of elongation at fracture was between 49.34 and 63.04%. In addition, the free volume in polymers plays a crucial role in facilitating the migration of molecular chain segments and is closely related to the macroscopic mechanical properties of polymers. A correlation analysis showed that the R value of the coating had the greatest influence on its tensile strength, while FV showed a higher correlation with the elongation at rupture.

The provenance of the stones in the Menga dolmen reveals one of the greatest engineering feats of the Neolithic

The technical and intellectual capabilities of past societies are reflected in the monuments they were able to build. Tracking the provenance of the stones utilised to build prehistoric megalithic monuments, through geological studies, is of utmost interest for interpreting ancient architectures as well as to contribute to their protection. According to the scarce information available, most stones used in European prehistoric megaliths originate from locations near the construction sites, which would have made transport easier. The Menga dolmen (Antequera, Malaga, Spain), listed in UNESCO World Heritage since July 2016, was designed and built with stones weighting up to nearly 150 tons, thus becoming the most colossal stone monument built in its time in Europe (c. 3800–3600 BC). Our study (based on high-resolution geological mapping as well as petrographic and stratigraphic analyses) reveals key geological and archaeological evidence to establish the precise provenance of the massive stones used in the construction of this monument. These stones are mostly calcarenites, a poorly cemented detrital sedimentary rock comparable to those known as 'soft stones' in modern civil engineering. They were quarried from a rocky outcrop located at a distance of approximately 1 km. In this study, it can be inferred the use of soft stone in Menga reveals the human application of new wood and stone technologies enabling the construction of a monument of unprecedented magnitude and complexity.

Flexural Behaviour of Skinned Beams with Different Shapes of Steel Mesh Confinements

- Jacketing is a popular technique in modern civil engineering for strengthening and modifying structures. It is used to increase bearing load capacity or to restore structural design integrity after the structural design has been altered or after a structural member has failed. This method is typically utilized for horizontal surfaces such as the bottom and sides of beams and vertical surfaces such as walls and columns. This study investigates the flexural performance of high-strength concrete beams reinforced with steel wire mesh in various forms, such as hexagonal steel wire mesh, square wire mesh, and diamond wire mesh, using the concept of dual-layer concrete. At First, three sets of 450 x 50 x 50 mm beams were cast, and three different mesh configurations were confined around the beam and filled with concrete to form 500 x100 x 100 mm beams. The flexural behaviour of these beams was carefully examined under load controlling machine (UTM). The study found that adding steel wire meshes to beams as confinement enhances their total flexural strength and the behaviour of the beams failure mechanism when subjected to two-point stress. The Flexural strength has been increased by an amount of 10%, 23% and 35% respectively for hexagonal, square and diamond meshes. However, the specimen restricted with diamond mesh wrapped around the inner core performs more effectively than the specimen with Square and hexagonal wrapped around the core in terms of Stress-strain curves and Young’s Modulus.

Ahead of His Time: Leonardo da Vinci’s Contributions to Engineering

Leonardo da Vinci, a polymath of the High Renaissance, is renowned for his contributions to the arts, most well-known being the "Mona Lisa" and "The Last Supper". However, Leonardo’s genius extended far beyond the realm of art, penetrating the fields of science and engineering, which were in their infancy during his lifetime. This paper delves into the lesser-known aspects of da Vinci's genius, focusing on his innovative ideas and designs that were far ahead of his era. It explores the breadth and depth of his engineering concepts, from the design of flying machines to the development of hydraulic systems. The paper reveals that da Vinci's engineering sketches and notes, often dismissed as fanciful during his time, have proven to be scientifically accurate and technologically feasible. His designs for machines such as the helicopter, parachute, and armored vehicle, though not realized in his lifetime, have significantly influenced modern engineering. Furthermore, his understanding of water dynamics has contributed to the development of modern hydraulic and civil engineering. This paper argues that da Vinci's engineering contributions, though not as widely recognized as his artistic works, are a testament to his unparalleled foresight and innovative spirit.

Seeking the Optimisation of Public Infrastructure Procurement with NEC4 ECC: A Peruvian Case Study

The modern civil engineering and construction sector requires collaborative work environments, learning and trust among all parties involved, qualities that are absent in the Peruvian reality. This study, which is based on an extensive literature review, investigates this challenge. The study reflects upon (i) the current situation of public works procurement in Peru and (ii) the New Engineering Contract (NEC), which has recently been implemented in Peruvian Special Public Infrastructure Projects. Comparisons are presented between the characteristics, documentation and roles of these two systems, with the purpose of understanding and representing the advantages, disadvantages and possibilities of integrating the good contractual management practices of the NEC4 Engineering and Construction Contract into the traditional Peruvian State Contracting Law (Ley de Contrataciones del Estado: LCE). The research is validated through the case study of a high-impact road infrastructure project in the city of Arequipa, Peru, which revealed five main deficiencies from Peruvian procurement processes which hinder good contractual management and, also, facilitated an initial assessment of the challenges and improvement opportunities in public infrastructure procurement. Thus, a contribution is made to closing the knowledge gap regarding the implementation of the NEC4 ECC in public sector works.

Crack Localization and Detection in Small-Scale Reinforced Concrete Beams With Smart Technology

Reinforced concrete structures form the backbone of modern civil engineering, yet the emergence of cracks poses a significant challenge to their long-term integrity. The integration of smart sensors and data analytics further augments precision by enabling real-time data collection and analysis, allowing for early intervention. Continuous monitoring, facilitated by remote sensing and wireless communication, ensures a dynamic understanding of crack propagation. To validate the proposed approach, an experimental campaign was conducted using reinforced concrete beams. Three point bending tests were conducted on two small-scale reinforced concrete beams. Different configurations of SEC arrays were used on the two specimens to assess the capacity and limitation of the proposed approach. Results show that the sensing skin was capable of detecting and localizing cracks that formed in both specimens.

Advancing civil infrastructure assessment through robotic fleets

Modern civil engineering structures, instrumented with Internet-of-Things-enabled smart sensors and actuators, are considered cyber-physical systems that integrate physical processes with computational and communication elements. This short communication aims to portray a milestone in the field of monitoring and inspection of civil infrastructure, collaboratively conducted by autonomous, robotic devices orchestrated in robotic fleets. It is expected that robot-based civil infrastructure assessment will revolutionize structural maintenance of the deteriorating building stock, which is increasingly exacerbated by the effects of climate change and develops into a major societal challenge.

Propose of sustainable engineering in a place for a social support for needy population

Leisure areas in cities are squares, urbanized green areas, museums, outdoor gyms, convention centers, multi-sports facilities, clubs, malls, theaters, cinemas, bars. Some areas that are not considered for leisure, but that play an important social role are the social assistance places where the needy population receives various types of assistance. Regarding these places, it is reasonable to ask whether they could be treated as leisure areas, associating them with green areas, gardens, outdoor gyms for a more humanized service. A descriptive/investigative research was carried out and the methods were field survey and bibliographical survey to base the hypothesis and reach the objective. The space used was a Religious Center that serves a needy population in a neighborhood of Alfenas − MG every day of the week. A plan was drawn up to make the environment more humane with alternatives to provide leisure and comfort for the population. The project proposal is feasible in accordance with the objectives of this work, but, in financial terms, other works could aim to budget and reduce the costs for its implementation, since the effectiveness of the theoretical data placed here fits within an Architecture project and Modern Civil Engineering.

The added mass of a closed-type cushion in uniform flow

Ethylene-Tetra-Fluoro-Ethylene (ETFE) cushions are popularly used in modern civil engineering structures. When a cushion vibrates in uniform flow, the surrounding fluid will be driven to move along with it. The inertia of fluid then produces an action on the cushion, which is known as the effect of added mass. This effect is usually very significant due to the light weight of these cushions. This paper proposes a new method to estimate the added mass on a close-type ETFE cushion vibrating in uniform flow with an improved accuracy compared with methods in the literature. The aerodynamic force is assumed to consist of pressures from uniform flow and potential flow induced by perturbation of the vibrating cushion. An analytical expression for the added mass on the cushion is then proposed based on the Laplace equation and Bernoulli equation, in which the velocity of the potential fluid above the vibrating cushion is assumed to vary along the z-direction in the form of a quartic function, and the non-uniform distribution of the added mass over the enveloping membrane is also considered. The proposed method is verified by comparing the dynamic responses of the cushion considering the added mass from the Computational Structural Dynamics (CSD) module of ADINA with those in the literature and those obtained from the fluid–structure interaction (FSI) analysis. The effects of different influencing factors on the accuracy of the method, e.g., side length of the cushion, initial inner pressure, wind velocity and wind direction angle, are further studied. Results show that: (a) the proposed method to estimate the added mass is more accurate than those in the literature with results closer to those from the FSI analysis; (b) an increase in the side length of the cushion will lead to a more non-uniform distribution of the added mass; (c) the side length of the cushion and wind velocity have a slight effect on the accuracy of the proposed method with the maximum error within 5%; and (d) an increase in the initial inner pressure can improve the accuracy of the proposed method while the wind direction angle seems to have little influence.

Study of the Compressive Properties of Heavy Calcium Carbonate-Reinforced Epoxy Composite Spheres (HC-R-EMS) Composite Lightweight Concrete.

Lightweight concrete is one of the effective means to solve the problems of structural component weight, energy efficiency, and fire safety in modern civil engineering. Heavy calcium carbonate-reinforced epoxy composite spheres (HC-R-EMS) were prepared by the ball milling method, and HC-R-EMS, cement, and hollow glass microspheres (HGMS) were mixed into the mold by the molding method to prepare composite lightweight concrete. The relationship between the HC-R-EMS volumetric fraction, the initial inner diameter of the HC-R-EMS, the number of layers of HC-R-EMS, the HGMS volume ratio, the basalt fiber length and content, and the multi-phase composite lightweight concrete density and compressive strength was studied. The experimental results show that the density of the lightweight concrete ranges between 0.953-1.679 g/cm3 and the compressive strength ranges between 1.59-17.26 MPa, where the volume fraction of HC-R-EMS is 90%, the initial internal diameter is 8-9 mm, and the number of layers of HC-R-EMS is three. The lightweight concrete can meet the requirements of high strength (12.67 MPa) and low density (0.953 g/cm3). In addition, the addition of basalt fiber (BF) can effectively improve the compressive strength of the material without changing the density of the material. From a micro-level perspective, HC-R-EMS is closely combined with the cement matrix, which is conducive to increasing the compressive strength of concrete. Basalt fibers connect the matrix into a network, improving the maximum limit force of the concrete.

On the existing test dataset of isotropic cylindrical metal shells under axial compression and the design of modern metal civil engineering shells

In the structural engineering limit state design philosophy of the Eurocodes, a target reliability is achieved by using partial safety factors on both the loading and the resistance that are, in principle, to be calibrated based on test data. The partial factor that is currently used for the buckling limit state of metal shells has been adopted from the knowledge base on other structural elements and has been retained for reasons of historical continuity and to maintain a close relationship between all Eurocode steel design standards. However, the mechanics of the behaviour of thin-walled metal shells gives strong reasons to believe that the partial factors for buckling should be dependent on the shell geometrical form, slenderness, load case and quality of fabrication for the target reliability to be consistently achieved. None of these are currently considered in defining the partial factor for resistance.The most ubiquitous thin-walled metal shell structures are imperfection-sensitive cylinders under uniform axial compression. A dataset of many hundreds of these test results has thus been accumulated over many decades, though it is of variable quality and sparsely documented. This paper shows that this dataset is an entirely inappropriate basis on which to calibrate the safety level of full-scale metal civil engineering shells. Indeed, the professional community should face the uncomfortable reckoning that an experimental test dataset suitable for the reliable calibration of the safety level of design relationships for full-scale metal civil engineering shells may likely never come into existance, and that the bolder approach of extensive computational simulation must instead be embraced.

Mechanistic understanding of precast UHPC segmental beams with external tendons and epoxy joints subject to combined bending and shear

Precast ultra-high-performance concrete (UHPC) segmental bridges (PUSBs) have become a competitive bridge type in modern civil engineering. To establish a thorough mechanistic understanding of PUSBs, seven specimens were fabricated and experimentally investigated. These specimens were designed to have different longitudinal reinforcements, construction methods, joint types, shear span-to-depth ratios (λ), stirrup ratios, and numbers of shear keys. Two failure modes were observed in the tests: flexural failure with crushing of the UHPC at the joints, and shear failure with shear tension sliding and concrete spalling of the web. Additionally, it was found that although the ultimate capacity, stiffness, and cracking load of the segmental beams were slightly lower than those of the monolithic beams, the segmental beams tended to exhibit better ductility and deformation capacity. As λ increased, the ultimate capacity and stiffness of the segmental beams decreased, whereas the growth rates of the deflection and tendon stress increased. Moreover, the stirrups showed a positive effect on the cracking control ability and shear strength of the beams. The three-keyed specimen exhibited better structural behavior than the single-keyed specimen. Finally, calculation methods were proposed to predict the cracking strength and ultimate capacity of PUSBs.

Influence of surfactant on foam generation and stabilization in cement slurry

Modern civil engineering and industrial buildings use foamed cement because of its low heat conductivity and light weight.Despite their high performance, foamed cement products manufactured solely from cement might be prohibitively expensive for commercial entities. Thus, chemically foaming cement is important. This paper compiles and reviewsthe foamed cement preparation, mostly used physical and chemical foaming processes. Physical foaming creates foamed cement by mixing foam into a slurry. Physical foaming methods are inefficient and energy-intensive. Chemical foaming involves adding a foaming ingredient to cement slurry. Foaming agents like surfactants react to create bubbles that expand the slurry. Surfactants in the liquid solution promote a bubble by spontaneously cicatrizing holes caused by external perturbations. These chemicals stabilize foams and bubbles for minutes to hours. Oil and gas well cementing uses Self-generated nitrogen foam cement (SNFC) with a high-efficiency foam stabilizer. Three surfactants produced cement pastes with and without MWCNT. A viscosity-modifying agent (VMA) in an aqueous cement paste dispersion can change its rheology. Sodium dodecyl sulfate (SDS) and CaCl2 increase nanosilica (NS) fluidity for pumping cement-based grout. FSCGM is used for coal mine infill grouting. Foamed sulfoaluminate cement-based grouting material (FSCGM) makes firefighting CO2 foam. Cement-hollow glass microballoon syntactic foams have greater compressive strength than neat cement at equal densities. Polydentatephosphonate-modified polymers and ester-type polycarboxylate superplasticizers create many cement mortar bubbles (PCE-1). Calcium ions stabilize polymer bubbles. Aqueous epoxy resin is added to cement slurries to reduce plastic viscosity and boost heat conductivity to make high-porosity cement foams (HPCF). Foamed cement bubble stability is highest at particle wetting angle π/2. SDS in silica suspension adjusts this angle. Ti-extraction blast furnace slag (TEBFS) foam with 20–40% sulfoaluminate cement (SAC) makes foamed cement.