Abstract This paper aims to propose a method of evaluating seismic damage on reinforced concrete moment frame structures with nonlinear finite element (FE) model updating. The proposed model simulates the nonlinear behavior of structures with Modified Ibarra–Medina–Krawinkler (MIMK) model and searches the parameters of the MIMK model with FE model updating. To reflect nonlinear local seismic behavior into the model updating, local structural response as well as global structural response are considered in the objective functions. To minimize two objective functions that are discrepancies of local strain and global displacement response between model and acquired data, multi-objective optimization algorithm is employed. To select the optimal solution among multiple solutions derived from model updating, an equation including a weight factor is proposed. The response of the updated model, which corresponds to the optimal solution selected by the equation including a weight factor, is validated by comparing it with the measured response, and the damage is evaluated using the hinge propagation and drift ratio of the updated model. In addition, the effectiveness of the proposed model is validated by using the high-intensity earthquakes that have not been used in the model updating procedure through nonlinear seismic response prediction and damage state identification.
Systems of building construction. Including fireproof construction, concrete construction
Abstract To achieve the dual goals of construction waste reutilization and carbon dioxide emission reduction, this study proposes a reinforced treatment method for recycled aggregates based on composite mineralization and further improves the secondary mineralization technique for fully recycled aggregate concrete (FRAC) to enhance its mechanical and durability properties. A chemical modification process using Ca(OH)₂ combined with composite mineralization was introduced to analyze its effects on both the macroscopic performance and microstructure of recycled aggregates. The optimized mineralized aggregates were then used to prepare FRAC, and the compressive strength after secondary mineralization was tested. In addition, a carbonation depth prediction model was established based on Fick’s first law to assess the carbonation behavior of FRAC. The results indicate that: (1) the optimal modification scheme for recycled concrete aggregates is 12 h composite mineralization using 0.3% Ca(OH)₂ solution, which reduces water absorption and crushing index by 15.68% and 19.15%, respectively. (2) A significant positive correlation exists between aggregate apparent density and CO₂ uptake (R2 = 0.965). (3) When recycled and mineralized aggregates are mixed in a 1:1 ratio in composite mineralized FRAC, the compressive strength after 7 day curing with secondary mineralization is comparable to that of natural concrete after 28 day standard curing. (4) The carbonation depth prediction model demonstrates a good fit (R2 > 0.85 in all cases), with prediction errors below 5%.These findings demonstrate that the synergistic effect of Ca(OH)₂-based composite mineralization and secondary mineralization can significantly improve the quality of recycled aggregates and their performance in concrete, offering strong potential for practical engineering applications.
Systems of building construction. Including fireproof construction, concrete construction
We construct a four-dimensional conformal amplitude whose four-point structure matches the Virasoro-Shapiro form familiar from string theory. The construction uses only general principles of conformal field theory - radial quantization, scale invariance, and analyticity - and does not rely on worldsheet geometry or string degrees of freedom. The resulting object is a kinematical, first quantized amplitude defined by symmetry and consistency, providing a four-dimensional realization of stringlike analytic structure and a concrete target for amplitude bootstrap approaches.
Abstract Reinforced concrete (RC) beams with vertical openings are becoming more frequent in new construction to transport numerous services, particularly in structures with restricted height and size. A significant lack of studies was observed to investigate the influence of a vertical opening in the shear zone on the RC beams' behavior and performance. This research investigated experimentally the performance of RC beams with vertical openings at the shear zone, whether these beams were cast with self-compacting concrete (SCC) or rubberized concrete (RUC). In addition, the purpose of this work is to compare the influence of steel fiber (SF) on the performance of vertically perforated SCC beams with its influence on the performance of vertically perforated RUC beams. The impact of the number of vertical openings and the SF ratio used in beam specimens on the beam behavior, including compressive and tensile strengths, crack patterns and modes of failure, maximum deflection, stiffness, loading capacity, and ductility, was evaluated in the current paper. The experimental findings demonstrated that the existence of vertical openings at the shear zone of SCC and RUC beams resulted in a decrease in stiffness with ratios ranging from 10.43 to 66.98%, maximum loading capacity with ratios ranging from 10.66 to 37.73%, and ductility index with ratios ranging from 2.14 to 21.53% compared to the solid beams. It also has a tangible impact on raising the maximum mid-span deflection at the ultimate load, ranging from 2.03 to 81.64%. Moreover, when the number of vertical openings increased, the cracks increased at the shear span in which the openings were located. In general, adding SF to the SCC mixture showed a more significant effect on enhancing the tensile and compressive strengths, stiffness, and ultimate load compared to that in the case of the RUC. For example, the stiffness and ultimate load of the solid SCC beam with a SF ratio of 1% increased by 164.58% and 70.19%, respectively, compared to the solid SCC beam without SF, while those of the solid RUC beam with the same ratio of SF increased by 69.91% and 61.85%, respectively.
Systems of building construction. Including fireproof construction, concrete construction
Nayanatara Gamage, Chamila Gunasekara, David W. Law
et al.
Abstract Carpet waste degrades slowly, posing an environmental burden. Incorporating this waste as fibre reinforcement in concrete helps to reduce accumulation and improve the properties of concrete. However, varying fibre characteristics and their interaction in blends are not well established. Hence, understanding hybrid fibre effects is crucial for construction adoption. This study evaluates the mechanical performance, shrinkage, microstructure, pore structure, and interfacial characteristics of hybrid carpet fibre-reinforced concrete. Four fibres, nylon, polypropylene (PP), polytrimethylene terephthalate (PTT), and polyester were analysed using grey relation analysis in six hybrid combinations with three mix ratios at a 0.3% volume fraction. At 28 days, flexural and splitting tensile strengths increased by 4–11% and 8–26%, respectively. All mixtures exhibited reduced shrinkage compared to the control. The nylon/PP 2:1 mix showed the best overall performance. Microstructural analysis revealed pore refinement, reduced porosity, and improved fibre–matrix bonding influenced by fibre hydrophilicity or hydrophobicity. Nanoindentation indicated hydrophilic fibres minimized the interfacial transition zone thickness. The findings indicate fibre combinations exhibit additive effects. This suggests performance can be predicted for blended fibre mixes, potentially allowing the design of mixes using fibre combinations to compensate for poorer performing fibres, enabling their reuse and avoiding landfill disposal.
Systems of building construction. Including fireproof construction, concrete construction
Finding and properly segmenting cracks in images of concrete is a challenging task. Cracks are thin and rough and being air filled do yield a very weak contrast in 3D images obtained by computed tomography. Enhancing and segmenting dark lower-dimensional structures is already demanding. The heterogeneous concrete matrix and the size of the images further increase the complexity. ML methods have proven to solve difficult segmentation problems when trained on enough and well annotated data. However, so far, there is not much 3D image data of cracks available at all, let alone annotated. Interactive annotation is error-prone as humans can easily tell cats from dogs or roads without from roads with cars but have a hard time deciding whether a thin and dark structure seen in a 2D slice continues in the next one. Training networks by synthetic, simulated images is an elegant way out, bears however its own challenges. In this contribution, we describe how to generate semi-synthetic image data to train CNN like the well known 3D U-Net or random forests for segmenting cracks in 3D images of concrete. The thickness of real cracks varies widely, both, within one crack as well as from crack to crack in the same sample. The segmentation method should therefore be invariant with respect to scale changes. We introduce the so-called RieszNet, designed for exactly this purpose. Finally, we discuss how to generalize the ML crack segmentation methods to other concrete types.
The hypergraph product (HGP) construction of quantum error-correcting codes (QECC) offers a general and explicit method for building a QECC from two classical codes, thereby paving the way for the discovery of good quantum low-density parity-check codes. In this letter, we propose a general and explicit construction recipe for QECCs from a total of D classical codes for arbitrary D. Following this recipe guarantees the obtainment of a QECC within the stabilizer formalism and nearly exhausts all possible constructions. As examples, we demonstrate that our construction recovers the HGP construction when D = 2 and leads to four distinct types of constructions for D = 3, including a previously studied case as one of them. When the input classical codes are repetition codes, our D = 3 constructions unify various three-dimensional lattice models into a single framework, encompassing the three-dimensional toric code model, a fracton model, and two other intriguing models not previously investigated. Among these, two types of constructions exhibit a trade-off between code distance and code dimension for a fixed number of qubits by adjusting the lengths of the different classical codes, and the optimal choice can simultaneously achieve relatively large values for both code distance and code dimension. Our general construction protocol provides another perspective for enriching the structure of QECCs and enables the exploration of richer possibilities for good codes.
Abstract To address the environmental issues arising from the growing scarcity of natural fine aggregates (NFA) and landfilling of waste glass, research is being conducted globally to utilize waste glass as a sustainable fine aggregate. However, contradictory results have been obtained regarding the effect of the type of waste glass and the physical properties of waste glass fine aggregate (GFA) on concrete, making it challenging to promote the use of GFA in concrete. Therefore, to promote the use of GFA in concrete, it is necessary to examine it under field conditions, such as mass-production processes or real-scale concrete applications. This study introduced a mass-production process for GFA, and the effect of mass-produced GFA on mortar was evaluated. The fine aggregate properties (particle aspect ratio, crushing rate, and solubility) of the GFA and the effects of color, content, and particle size on the mortar properties (compressive strength, flexural strength, and ASR expansion behavior) were analyzed, along with the results reported in previous studies. Consequently, the high aspect ratio and microcracks in the particles of mass-produced GFA led to an increase in the strength reduction and ASR expansion of the mortar. These effects appear to be particularly severe for transparent GFA. Overall, this study proposed the content of GFA within 20% or the replacement of fine particles (< 500 μm) in NFA as a condition for sustainable fine aggregate.
Systems of building construction. Including fireproof construction, concrete construction
The article is devoted to the study of the issues of legal regulation of the procedure and forms of interaction between the investigator and the expert at the stage of checking crime report related to the fire. Based on the analysis of the peculiarities of the forensic characteristics of these crimes, as well as on the novel of the criminal procedure legislation, the conclusion is formulated on the need to introduce changes to the criminal procedure legislation aimed at consolidating the evidentiary value of the preliminary expert conclusion.
Systems of building construction. Including fireproof construction, concrete construction
Alexander A. Abashkin, Boris B. Kolchev, Irek R. Khasanov
The article discusses the features of arrangement of smoke protection systems in double-track subway tunnels. The calculation method for the smoke ventilation system parameters is presented, taking into account the factor of longitudinal slope, the heat release power of the fire source, as well as the tunnel characteristics. There are proposed the various schemes of supply and exhaust smoke ventilation systems in double-track tunnels of the Moscow Metro.
Systems of building construction. Including fireproof construction, concrete construction
In the present paper, we give a complete description of the group of holomorphic automorphisms of the Cox construction of a simplicial fan equivariant with respect to a large enough connected complex Lie subgroup of the large torus acting on the Cox construction. We then apply this description to find the groups of holomorphic automorphisms of rational moment-angle manifolds, including Calabi--Eckmann manifolds and Hopf manifolds. We also calculate the groups of equivariant automorphisms of complete simplicial toric varieties. This paper is the first in a series of two papers dedicated to studying the automorphism groups of toric stacks with applications to complex geometry.
The classical theory of plane projective geometry is examined constructively, using both synthetic and analytic methods. The topics include Desargues's Theorem, harmonic conjugates, projectivities, involutions, conics, Pascal's Theorem, poles and polars. The axioms used for the synthetic treatment are constructive versions of the traditional axioms. The analytic construction is used to verify the consistency of the axioms; it is based on the usual model in three-dimensional Euclidean space, using only constructive properties of the real numbers. The methods of strict constructivism, following principles put forward by Errett Bishop, reveal the hidden constructive content of a portion of classical geometry. A number of open problems remain for future studies.
Ridwan Taiwo, Idris Temitope Bello, Sulemana Fatoama Abdulai
et al.
The construction industry is a vital sector of the global economy, but it faces many productivity challenges in various processes, such as design, planning, procurement, inspection, and maintenance. Generative artificial intelligence (AI), which can create novel and realistic data or content, such as text, image, video, or code, based on some input or prior knowledge, offers innovative and disruptive solutions to address these challenges. However, there is a gap in the literature on the current state, opportunities, and challenges of generative AI in the construction industry. This study aims to fill this gap by providing a state-of-the-art analysis of generative AI in construction, with three objectives: (1) to review and categorize the existing and emerging generative AI opportunities and challenges in the construction industry; (2) to propose a framework for construction firms to build customized generative AI solutions using their own data, comprising steps such as data collection, dataset curation, training custom large language model (LLM), model evaluation, and deployment; and (3) to demonstrate the framework via a case study of developing a generative model for querying contract documents. The results show that retrieval augmented generation (RAG) improves the baseline LLM by 5.2, 9.4, and 4.8% in terms of quality, relevance, and reproducibility. This study provides academics and construction professionals with a comprehensive analysis and practical framework to guide the adoption of generative AI techniques to enhance productivity, quality, safety, and sustainability across the construction industry.