The increasing demands of this modern infrastructure require greater structural performance and long-term sustainability while being cost-effective. For a long time, the quest for such construction materials required durable, intelligent, and cost-effective construction materials. The traditional cementitious materials are very common; however, they have some innate drawbacks: they crack rather easily, cannot self-heal, and lack some damage-monitoring mechanisms for its real-time assessment. Current solutions for structural health monitoring involve extrinsic sensors and wiring that are invasive and costly and do not provide integrated self-healing and damage detection predictivity. This research introduces the work on multi-functional carbon nanotube (CNT) infused smart cement capable of presenting enhanced mechanical performances, in situ damage sensing, and autonomous self-healing capabilities. Key methods used include: 1) chemical functionalization of CNT for better dispersion, bonding, and conductivity, which improves mechanical strength by 30% and electrical conductivity 10-fold; 2) CNT catalyzing microencapsulated self-healing system: more than 85% crack closure efficiency for cracks up to 0.5 mm; 3) three-dimensional printing with CNT infused cement, enabling the creation of complex geometries with embedded sensors, porosity control, and 20% greater structural integrity; 4) wireless damage monitoring using CNT-based antennas for crack detection below 0.1 mm and signal transmission over 50 m; and 5) artificial intelligence (AI)-enhanced predictive maintenance, achieving a prediction accuracy of 95%–98% in crack propagation and reducing maintenance costs by 30%. This novel integration of functionalized CNT, self-healing agents, wireless sensing, and AI-driven analytics simultaneously strengthens structural integrity while permitting sustainable, non-invasive, and scalable monitoring. What these results indicate is enhanced performance, cost-effectiveness, and longevity, making the technology transformative for the next generations of construction materials.
Concrete is among the most utilized and essential construction materials in terms of strengthening the structure. The use of natural aggregates can be reduced by using crumb rubber aggregates (RA) as a substitute. The use of RA will reduce the expense on aggregate and help in creating a sustainable environment. Nanoparticles improve the microscopic structure of concrete by filling pores present in cement paste thus reducing the cement usage in the mix. Employing nano titanium dioxide (NT) in rubber concrete (RC) helps to improve its properties. The findings showed that RA significantly alters the characteristics of the concrete; at a 15% level of fine aggregate (FA) replacement, the workability and density of the concrete mixes dropped by up to 26.53% and 5%, respectively. Concrete’s compressive, tensile, and flexural strengths decreased by 16.1%, 5.52%, and 3.1%, respectively, as a result of adding RA. However, these negative effects were successfully offset by the addition of NT. Even while workability declined, density grew. The research shows that the use of NT in RC composites enhances corrosion resistance and durability, reduces porosity, and improves permeability. The research also suggests that NT helps to smoothen pores and microcracks in concrete, resulting in enhanced resistance to elements such as water and air. This study employs analysis of variance to evaluate the mechanical and durability characteristics of rubberized concrete composites. Microstructural investigation employing field emission scanning electron microscopy examines the interfacial transition zone, hydration products, and pore structure, offering insights into the influence of NT on concrete matrix. This study offers thorough, significant information on the application of NT nanoparticles as a green and efficient additive to enhance concrete performance, and it also presents potential for additional studies in this area of study.
Quasi-static experiments and analytical investigations of ultra-high-strength bars (UHSB) reinforced walls with two shear span ratios of 1.5 and 2.2, were conducted. The hysteretic responses of test walls in terms of damage evolution, load–displacement curves, curvature profiles, reinforcement strain, and residual drift ratio were explored. Experimental results indicated that all test walls exhibited drift-hardening behavior. Specimens achieved a maximum residual drift ratio of 0.27% before 2% drift ratio, satisfying the limit value of 0.5%. The calculation of hysteresis curves calculation of the test walls was conducted considering the weak bond behavior of UHSB and verified by the experimental results.
The protection of historical artifacts that hold great significance in the fields of art, architecture, history, and culture ensures the preservation of cultural heritage and safeguards the shared past of humanity. Proper material selection and appropriate application methods are crucial for maintaining the aesthetic and structural integrity of historical structures and ensuring their transmission to future generations. Understanding the composition and properties of these materials is essential for making the right material choices in restoration processes. This study aims to provide a detailed evaluation of analytical methods used in the characterization of historical building materials and to synthesize the existing findings in the literature in a coherent manner. At the same time, it aims to provide a guide for researchers in the field in choosing the methodology by revealing the strengths and limitations of these techniques. Thus, it will contribute to the establishment of a data-based basis for future scientific studies. In this context, the objectives of the methods used to determine the properties of historical building materials, the processes of sampling and preparing materials for testing, the characteristics of the devices used in the tests, as well as the obtained analysis results and evaluations were reviewed.
The precast segmental column (PSC) plays a vital role in both the design of new bridges and the rehabilitation of existing ones. Previous studies of PSCs have primarily focused on their individual seismic behavior. However, research on the seismic performance of entire bridges supported by PSCs, particularly those incorporating soil−structure interaction (SSI), remains limited. Moreover, the amplification of earthquake waves as they propagate along the pile foundation to the surface, coupled with the coherency loss between earthquake motions at varying supports, may further impact the seismic responses of such bridges. This study systematically assesses the seismic performance of a PSC bridge (PSCB) supported by pile foundations considering the effects of SSI and depth-varying multi-support ground motions. Moreover, a benchmark bridge with the traditional monolithic column is also analyzed for comparison. The seismic fragility of bridges is calculated based on nonlinear time history analyses and joint probability density functions for both peak and residual responses. Parameter studies are conducted to reveal the influences of SSI, non-uniform excitation, and depth-varying earthquake loads on seismic performance assessments. This paper offers valuable insights for the reliable analysis of seismic response and fragility and the safety design of PSCB systems.
In engineering systems, uncertainties in input parameters can significantly influence the output responses. This paper proposes a model distance-based approach to perform global sensitivity analysis for quantifying the influence of input uncertainties on multiple responses in an engineering system. The sensitivity indices are determined by comparing a reference model that incorporates all system uncertainties, with an altered model, where specific uncertainties are constrained. The proposed framework employs probability distance measures such as Hellinger distance, Kullback–Leibler divergence, and l2 norm which are based on joint probability density functions. The study also demonstrates the equivalence between the l2 norm-based approach and Sobol’s analysis in multivariate sensitivity context. The proposed methodology effectively manages correlated random variables, accommodates both Gaussian and non-Gaussian distributions, and allows for the grouping of input variables. Illustrative examples consist of static analysis of a truss system and dynamic analysis of a frame subjected to seismic excitation. The sensitivity indices are estimated using brute-force Monte Carlo simulations. The relative ranking of these sensitivity indices can be utilized to identify the most and least significant variables contributing to the response uncertainty. The numerical results show a consistent ranking of input variables across different probability measures, indicating the robustness of proposed framework.
The vibration analysis of Kirchhoff plates requires robust mass lumping schemes to guarantee numerical stability and accuracy. However, existing methods fail to generate symmetric and positive definite mass matrices when handling rotational degrees of freedom, leading to compromised performance in both time and frequency domains analyses. This study proposes a manifold-based mass lumping scheme that systematically resolves the inertia matrix formulas for rotational/torsional degrees of freedom. By reinterpreting the finite element mesh as a mathematical cover composed of overlapping patches, Hermitian interpolations for plate deflection are derived using partition of unity principles. The manifold-based mass matrix is constructed by integrating the virtual work of inertia forces over these patches, ensuring symmetry and positive definiteness. Numerical benchmarks demonstrate that the manifold-based mass lumping scheme performance can be comparable or better than the consistent mass scheme and other existing mass lumping schemes. This work establishes a unified theory for mass lumping in fourth order plate dynamics, proving that the widely used row-sum method is a special case of the manifold-based framework. The scheme resolves long-standing limitations in rotational/torsional inertia conservation and provides a foundation for extending rigorous mass lumping to 3D shell and nonlinear dynamic analyses.
Currently, the reinforcement design of shield tunnel secondary linings mainly depends on engineering experience, with a lack of clear guidance from relevant codes and literature. Relying only on experience during construction can cause structural flaws and safety hazards. This study, based on the Guangzhou–Shenzhen–Hong Kong Shiziyang Tunnel project, uses model tests to study shield tunnel double-layer lining structures. It compares and analyzes the mechanical features and interaction mechanisms of reinforced and unreinforced secondary linings. Results show that in such structures, segmental linings bear the main load, and secondary linings offer extra support and adjust deformation. Reinforcement in secondary linings affects the constraint on segmental linings. Reinforcement enhances overall performance significantly. Although it has little impact on ultimate bearing capacity, it prolongs the load-bearing process. Specifically, it increases the ultimate bearing capacity of segmental and secondary linings by 21.2% and 26.1%, respectively. For 10-m-diameter shield tunnels, secondary lining reinforcement design should be adopted when the equivalent overburden thickness at the tunnel crown exceeds three times the tunnel diameter.
Evaluation of concrete structures in nuclear power plants (NPPs) under long-term irradiation exposure is important to ensure a safe and reliable operation of NPPs during extended service life from 40 to 80 years. In this study, a comprehensive multiscale framework of theoretical models was developed to predict the deformation and degradation of mechanical properties of concrete materials subject to long-term neutron irradiation. The generalized self-consistent model and the Mori–Tanaka model were used to characterize the mechanical properties of concrete with multiple phases and multiple scale internal structures. The overall expansion and degradation of mechanical properties of concrete resulted from neutron irradiation as well as elevated temperature were estimated using a composite damage mechanics approach. The neutron radiation-induced degradation, volumetric expansion of aggregates, thermal strains, and shrinkage of cement paste were considered in the comprehensive model. The model can be used as a predictive tool for the effect of long-term neutron irradiation on concrete used in NPPs.