Hasil untuk "Systems of building construction. Including fireproof construction, concrete construction"

Sharareh Shirzad, Ehsan Mahyari, Jonathan Culpepper et al.

Jian Fu, Zilin Wang, Xuewei Li et al.

Abstract The incorporation of high-titanium slag may reduce the crack resistance of concrete. To promote the recycling of industrial solid waste while maintaining structural integrity, this study investigates the use of high-titanium slag as a replacement aggregate in concrete, supplemented with polyvinyl alcohol (PVA) fibers to enhance toughness, crack resistance, and flexural and tensile properties. Semicircular bending (SCB) specimens were subjected to loading, and their strain and displacement fields were monitored in the full time domain using digital image correlation (DIC) technology. Multiple indicators were proposed to evaluate the crack resistance provided by the fibers. Scanning electron microscopy (SEM) was employed to observe the micromorphology of the fibers and the cementitious matrix, revealing the mechanisms underlying the enhanced crack resistance. Results demonstrate that with 0.5% vol. PVA fiber addition, the peak load capacity increased by 17.2%, total fracture work improved by 52.6%, and the failure duration extended by 1.30 s. Quantitative DIC analysis revealed that fiber reinforcement reduced maximum strain concentration by 83.8% (from 5.204 to 0.843%) and decreased lateral displacement difference across cracks by 46% (from 0.35 to 0.19 mm). The enhanced performance is applicable within the tested fiber content range (0–0.5% vol.) and is particularly effective for concrete mixtures where high-titanium slag replacement exceeds 50% of total aggregate volume. However, the crack resistance improvement may be constrained by fiber dispersion quality and interfacial bonding strength. This study not only facilitates the high-value utilization of industrial solid waste, but also significantly improves the crack resistance of concrete, offering broader potential for the application of high-titanium slag in construction materials.

Hongbo Liu, Cheng Zhang, Chen Jia et al.

E. Ferrier, C. Le Roy, A. Gagnon et al.

David G. Nagy, Tingke Shen, Hanqi Zhou et al.

Humans flexibly construct internal models to navigate novel situations. To be useful, these internal models must be sufficiently faithful to the environment that resource-limited planning leads to adequate outcomes; equally, they must be tractable to construct in the first place. We argue that analogy plays a central role in these processes, enabling agents to reuse solution-relevant structure from past experiences and amortise the computational costs of both model construction (construal) and planning. Formalising analogies as partial homomorphisms between Markov decision processes, we sketch a framework in which abstract modules, derived from previous construals, serve as composable building blocks for new ones. This modular reuse allows for flexible adaptation of policies and representations across domains with shared structural essence.

Osamu Fukushima, Takaki Matsumoto, Kentaroh Yoshida

We consider the Courant-Hilbert (CH) construction of integrable deformations of a two-dimensional principal chiral model (2D PCM) in the context of the four-dimensional Chern-Simons (4D CS) theory. According to this construction, an integrable deformation of 2D PCM is characterized by a boundary function. As a result, the master formula obtained from the 4D CS theory should be corrected by the trace of the energy-momentum tensor so as to support the CH construction. We present some examples of deformation including the $T\bar{T}$-deformation, the root $T\bar{T}$-deformation, the two-parameter mixed deformation, and a logarithmic deformation. Finally, we discuss some generalizations and potential applications of this CH construction.

Ramesh Gomasa, Visalakshi Talakokula, Sri Kalyana Rama Jyosyula et al.

Mahmoud Sadeghpour, Mohammadreza Baradaran

Aron Berhanu Degefa, Geonyeol Jeon, Sooyung Choi et al.

Abstract Supplementary cementitious materials (SCMs) play an essential role in sustainable construction due to their potential to reduce carbon emissions, promote circular economy principles, and enhance the properties of concrete. However, the inherent diversity of SCMs makes it challenging to predict their degree of reaction (DOR). This study applies machine learning techniques to predict DOR while exploring key parameters affecting it. Five machine learning models are utilized: linear regression, Gaussian process regression (GPR), decision tree regression, support vector machine and extreme gradient boosting, with GPR providing the most accurate and adaptable prediction. The study delves into the impact of various parameters on DOR, revealing their significance. Silica content emerges as the most critical, followed by particle size distribution, specific gravity, and water-to-cement (W/C) ratio. Optimizing DOR requires extending curing time, reducing particle size distribution, and considering optimal silica content and W/C ratio. This research emphasizes the importance of understanding the relationships between parameters and the DOR of SCMs, providing insights to enhance the efficiency of SCMs in cementitious systems through machine learning and data-driven analysis.

Ali Jahami, Camille A. Issa

Qi Kang, Jingxin Bao, Ran Li et al.

Abstract The study discussed the effects of different mineral incorporations and the curing time on the strength of modified magnesium phosphate cement (MPC) mortars through mechanical tests, mathematical model analysis and microstructure characterization. Fly ash (FA), silica fume (SF), and metakaolin (MK), which exhibit excellent durability and bonding properties, were used to modify the MPC. A quantitative relationship was established between the strength of modified MPC mortars and the mineral incorporation and curing time. First, the strength of each mineral-modified MPC mortar cured in air with different mineral incorporations and curing durations was evaluated. The strengths of MPC mortars containing 10% fly ash, 15% silica fume, and 10% metakaolin—which perform best in their incorporations—were compared to analyze the function of the three minerals. To establish the relationship between strength and mineral incorporation and curing time, three mathematical models, linear model, general nonlinear model, and data distribution shape nonlinear model (DDSNM), are commonly used for material property analysis based on statistics. DDSNM best describes the trend of strength change among the three models and the error is small for three minerals. Based on DDSNM, the influence of various minerals on the strength of MPC mortar was quantitatively evaluated by calculating the variable partial derivatives, and verified by scanning electron microscopy and X-ray diffraction. MK performs the best in improving the flexural strength performance of MPC, while SF performs the best in the compressive strength. FA-MPC has low sensitivity to dosage fluctuations and is easy to prepare.

Sukmin Kwon, Sugyu Lee, Hyunuk Kang et al.

Abstract Although concrete materials generally exhibit outstanding mechanical properties, it is susceptible against crack formation. It has been reported that narrow cracks (≤ 150 µm) could be naturally sealed in the cement matrix by externally supplied water-induced hydration. However, the crack width of larger than 150 µm is difficult to be sealed without using additional self-healing admixture. In this study, the self-healing cementitious mortar was successfully developed by using a combination of polyvinyl alcohol (PVA) fiber and superabsorbent polymer (SAP), aiming to heal the wide cracks. Although the mechanical properties were slightly reduced, it shows outstanding self-healing performance by using the dual admixtures. A self-healing rate of 60% was observed in the control sample with an initial crack width of 300 µm, while a self-healing rate of nearly 100% was confirmed with suitable SAP and PVA. In addition, it was confirmed that lower hydration degree of self-healing mortar in early stage contributes to the enhanced self-healing performance of developed composite system by internally supplied water from SAP.

Mahdi Ben Ftima, Emre Yildiz

Abstract This work focuses on the failure mechanisms of concrete hydroelectric facilities affected by alkali–aggregate reaction (AAR). Identification of potential failure mechanisms is based on an original “top-down approach” using an AAR pushover analysis with multi-physics numerical simulation of a representative hydroelectric facility. Different global rehabilitation scenarios based on slot-cutting and grouting techniques are discussed and compared, using different performance metrics. A new quantitative performance metric, specifically developed for the nonlinear sophisticated analysis tool and considering the volumetric cracking caused by AAR is also suggested. Based on comparison results, a combination of grouting after a partial slot-cutting in the neighborhood of the discontinuities, appears to provide the best compromise in terms of stress relief and extent of cracking. New AAR benchmark problems, issued from the top-down approach, are also suggested for the first time in the literature.

Pawel Sikora, Levent Afsar, Sundar Rathnarajan et al.

Abstract The use of alternative and locally available materials is encouraged in the construction industry to improve its sustainability. Desert regions with shortages in freshwater and river sand as fine aggregates in concrete have to search for alternative materials such as seawater, dune sand, and waste glass powder to produce lightweight concretes. The potential negative effects of adding these alternative materials can be reduced by adding nanosilica to the cementitious system at very low quantities. This study evaluates the feasibility of using these alternative materials and nanosilica (NS) in producing lightweight aggregate concretes (LWACs). A systematic study was carried out to understand the synergistic effect of nanosilica and seawater in improving the hydration characteristics of the developed cementitious systems. Also, the effect of these alternative materials on the fresh properties of the cementitious system was assessed by slump flow tests. The evolution of compressive strength at early ages was investigated after 2, 7, and 28 days of moist curing and an improvement in the strength development in concretes with seawater was observed. Furthermore, the integrity of the developed LWACs was analyzed using oven-dry density, thermal conductivity, water porosity and shrinkage measurements. Moreover, the capillary porosity and sorptivity measurements revealed the denser microstructure in the nano-modified seawater lightweight concretes. In the end, the life-cycle assessment study calculated the benefit of alternative materials in terms of carbon footprint and water consumption. As an outcome, a sustainable solution for producing LWACs containing seawater, dune sand or glass powder was proposed.

Sina Lotfollahi, Alireza Jaidari, Parham Bakhtiari et al.

Abstract The main objective of the present research is to investigate the effect of adding wollastonite microfibers and waste tire rubber on the mechanical properties of concrete. For this purpose, two different series of mixtures were considered. Different percentages (5, 10, 15, and 20 percent) of wollastonite microfibers were added to the ordinary concrete and tested in the first series. Then, in the second series, wollastonite microfibers were added to the specimens in the amount of 20% by the weight of cement, and waste tire rubber was replaced with fine aggregate in different percentages (3, 5, 7, and 10 percent by the weight of fine aggregate), and the specimens were tested again. All the specimens were cured at the two ages of 7 and 28 days, and they were tested for the slump, compressive strength, tensile strength, and flexural strength. The results showed that the addition of 20% wollastonite microfibers to the specimens increased the compressive, flexural, and tensile strengths of the concrete at 28 days of age by 16, 87, and 78%, respectively, compared to the control specimen. The outcomes also demonstrated that replacing fine aggregate with tire rubber in samples containing 20% wollastonite microfibers reduces the strength of the samples. The highest reduction is related to the sample containing 20% of waste tire rubber, which has a reduced compressive strength of about 20% compared to the control sample. Furthermore, the results of this research showed that adding wollastonite microfibers to concrete reduces the concrete slump, while the density of the samples increases with the addition of wollastonite. Moreover, the presence of wollastonite microfibers reduces the porosity of concrete, but there is an increase in the number of pores in concrete samples containing waste tire rubber.

Jacob Biamonte

There are several known techniques to construct a Hamiltonian with an expected value that is minimized uniquely by a given quantum state. Common approaches include the parent Hamiltonian construction from matrix product states, building approximate ground state projectors, and, in a common case, developing penalty functions from the generalized Ising model. Here we consider the framework that enables one to engineer exact parent Hamiltonians from commuting polynomials. We derive elementary classification results of quadratic Ising parent Hamiltonians and to generally derive a non-injective parent Hamiltonian construction. We also consider that any $n$-qubit stabilizer state has a commutative parent Hamiltonian with $n+1$ terms and we develop an approach that allows the derivation of parent Hamiltonians by composition of network elements that embed the truth tables of discrete functions into a kernel space. This work presents a unifying framework that captures components of what is known about exact parent Hamiltonians and bridges a few techniques across the domains that are concerned with such constructions.

Saika Wong, Chunmo Zheng, Xing Su et al.

Contract review is an essential step in construction projects to prevent potential losses. However, the current methods for reviewing construction contracts lack effectiveness and reliability, leading to time-consuming and error-prone processes. While large language models (LLMs) have shown promise in revolutionizing natural language processing (NLP) tasks, they struggle with domain-specific knowledge and addressing specialized issues. This paper presents a novel approach that leverages LLMs with construction contract knowledge to emulate the process of contract review by human experts. Our tuning-free approach incorporates construction contract domain knowledge to enhance language models for identifying construction contract risks. The use of a natural language when building the domain knowledge base facilitates practical implementation. We evaluated our method on real construction contracts and achieved solid performance. Additionally, we investigated how large language models employ logical thinking during the task and provide insights and recommendations for future research.

Tae-Hoon Kim

Abstract This paper presents a nonlinear analysis procedure for the seismic performance assessment of deteriorated reinforced concrete bridges using a modified damage index. A finite-element analysis program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), is used to analyze deteriorated two-span simply supported reinforced concrete bridges. The new nonlinear material models for deteriorated reinforced concrete behaviors were proposed, considering corrosion effects as shown in a reduction in reinforcement section and bond strength. A modified damage index aims to quantify the seismic performance level in deteriorated reinforced concrete bridges. Several parameters of two-span simply supported deteriorated reinforced concrete bridge have been studied to determine the seismic performance levels. The newly developed analytical method for assessing the seismic performance of deteriorated reinforced concrete bridges is verified by comparison with the experimental and analytical parameter results.

Aleksey V. Kazakov, Denis V. Poltavets, Svetlana Yu. Khatuntseva et al.

As a result of numerous experiments it was found that often the effectiveness of fire extinguishing seats with high development dynamics is provided by means and methods of extinguishing, which allow for a short time from a safe for the operator distance to supply directly to the combustion zone the necessary amount of extinguishing powder composition optimal for its suppression [1–5]. The pulse feeding method meets this goal to the greatest extent.

Andrea Caforio, F. B. Durak, S. Vaudenay