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Flexural behavior of textile reinforced mortar-autoclaved lightweight aerated concrete composite panels

Frontiers of structural and Civil engineering 2024年第5期18卷 776-787页

作者： Liying GUO Mingke DENG Wei ZHANG Tong LI Yangxi ZHANG Mengyu CAO Xian HU Department of Civil Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Key Lab of Structural Engineering and Earthquake Resistance Ministry of Education(XAUAT)Xi’an 710055China Scene engineering design institute Xi’an 710016China Dahua Group Shang hai 200062China

To improve the deficiencies of prefabricated autoclaved lightweight aerated concrete(ALC)panel such as susceptibility to cracking and low load-bearing capacity,a textile-reinforced mortar-autoclaved lightweight aerated concrete(TRM-ALC)composite panel was developed in this *** group of reference ALC panels and five groups of TRM-ALC panels were fabricated and subjected to four-point flexural *** was applied on the tensile side of the ALC panels to create *** variable parameters were the plies of textile(one or two),type of textile(basalt or carbon),and whether the matrix(without textile)was applied on the compression side of *** results showed that a bonding only 8-mm-thick TRM layer on the surface of the ALC panel could increase the cracking load by 180%−520%.The flexural capacity of the TRM-ALC panel increased as the number of textile layers *** reinforcement of the matrix on the compressive side could further enhance the stiffness and ultimate loadbearing capacity of the TRM-ALC *** panels with basalt textile failed in flexural mode,with the rupture of fabric *** with carbon textile failed in shear mode due to the ultra-high tensile strength of *** addition,analytical models related to the different failure modes were presented to estimate the ultimate load-carrying capacity of the TRM-ALC panels.

关键词： prefabricated autoclaved lightweight aerated concrete panel textile-reinforced mortar cracking load flexural capacity stiffness

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Snap-interlock module system: Exploring an alternative architectural construction method

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International Journal of Space Structures 2023年第2期38卷 129-140页

作者： Song, Jin Young Vrana, Dan Heo, Seoyoung He, Xiangdong Shim, Jongmin Department of Architecture University at Buffalo BuffaloNY United States Department of Civil Structural and Environmental Engineering University at Buffalo BuffaloNY United States

Responding to the rise of temporary architecture motivated by fast changing cultural and societal interests, construction methods must be adapted to meet the needs of reconfigurable systems. The prototype of Snap-Interlock Module System (SIMS) proposed in this study aims to integrate the simplicity of dry stacking as a primitive construction method through a coordinated joint system in order to increase material efficiency and structural integrity. This study explores a method of stacking blocks using unique interconnecting mechanisms without bonding agents to allow for reconfigurability. The considered unit of SIMS is configured to have four legs with integrated hooks on both top and bottom, allowing each block to snap into four adjacent blocks on either end. The centerpiece is designed such that each block can individually possess geometric versatility toward organic growth of the whole system. Larger assemblies of SIMS blocks can create full-scale structures without the use of bolting, welding, or other bonding agents. Finite element analysis demonstrates that the explored interlocking motion falls into the elastic range of the considered steel and confirms that structural integrity can be secured at the building scale as well. In order to test the proof-of-concept, 1:3 scaled Polylactic Acid (PLA) blocks are 3D printed and assembled into a 2.5 m tall portal frame, leading to a full-scale structural model executed with six full-scale steel blocks. The assembly and disassembly of both prototype structures are easily executed by a single individual. Despite the limitations of the chosen fabrication methods and material choices, the study promises diverse applications in the changing urban context and contributes to the broader sustainability of our built environment via an alternative and reconfigurable construction method. © The Author(s) 2023.

关键词： structural integrity

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Proof-of-Concept of a Bayesian Updating Approach for Corrosion Degrees on the Basis of Crack Measurements 20th

Proof-of-Concept of a Bayesian Updating Approach for Corrosi...

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20th fib Symposium on ReConStruct: Resilient Concrete Structures, 2024

作者： Martens, Constantijn Botte, Wouter Caspeele, Robby Verstrynge, Els Materials and Construction group Civil Engineering Department KU Leuven Belgium Department of Structural Engineering and Building Materials Faculty of Engineering and Architecture UGent Belgium

ISBN: (纸本)9782940643257

A common problem with existing reinforced concrete (RC) structures is the occurrence of early signs of deterioration, sometimes even leading to collapse before reaching their design service life. The alarming issue of reinforcement corrosion and related concrete deterioration leads to significant reductions in structural safety and very high repair costs. Consequently, determining the corrosion degree of structural RC elements is a crucial step in the damage assessment process. The condition assessment of RC structures is often based on visual inspections, accompanied by tapping and crack mapping. Crack width measurements hence serve as an important damage parameter. Nevertheless, a quantitative approach to use these measurements in order to estimate the corrosion degree accounting for all relevant uncertainties is still missing. In this contribution crack width measurements are used to update the corrosion degree and the associated uncertainties by means of Bayesian updating. The posterior distribution of the corrosion degree is computed adopting Markov Chain Monte Carlo sampling and existing (semi-)empirical models, taking due consideration of the model and measurement errors. Finally, also spatial variability of the corrosion degree is accounted for by means of random field modelling. The experimental data for this research are obtained from an accelerated corrosion test program on RC specimens, in which beams are corroded uniformly by using an accelerated corrosion setup with an impressed current and a 5% NaCl solution. The posterior distribution of the corrosion degree enables a better estimation of the RC element's failure probability and remaining service life, contributing to a comprehensive understanding of its structural health. © fédération internationale du béton (fib).

关键词： Markov chains

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Reconstruction and rehabilitation of the Grand Al-Nouri Mosque dated to the twelfth century: a case of study

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Journal of engineering and Applied Science 2023年第1期70卷 108页

作者： Aboelhassan, Mohamed Gamal Tarabia, Ahmed Mokhtar Hassan, Sherif Farag Department of Civil Engineering Higher Institute of Engineering and Technology King Marriott Alexandria Egypt Department of Structural Engineering Faculty of Engineering Alexandria University Alexandria Egypt Department of Architecture Faculty of Fine Arts Alexandria University Alexandria Egypt

This paper aims to present the structural design and the rehabilitation process as well as the site assessment of the reconstruction and rehabilitation of the twelfth-century Grand Al-Nouri Mosque in Al-Nouri Complex, which is a part of the project Revive the Spirit of Mosul in Iraq. UNESCO launched the project Revive the Spirit of Mosul in February 2018 in order to reconstruct the old city after the destruction and looting from the wars with ISIS (Daesh) in 2017. Al-Nouri Complex includes the Great Al-Nouri Mosque and the 45-m-high Al-Hadba Minaret, which are the iconic historic landmarks of the old city of Mosul on the western side of the Tigris River, and it was built by Nur Al-Din Zengi during the twelfth century. Al-Nouri Mosque was reconstructed in 1942 using the original 40 octagonal Moslawi marble columns, and alabaster arches, the mihrab brought from the Ummayad Mosque in Mosul dates back to 956 AD, masonry stones, and a reinforced concrete roof. In this paper, the structural performance of Al-Nouri Mosque has been investigated through site observations, experimental tests, and structural analyses. Due to the several destructive earthquakes recorded around Mosul, a 3D finite element model of the whole mosque using a commercial finite element program has been developed considering the actual material properties and the effect of wind and seismic actions. Generally, the output results of the structural analysis models showed that the obtained compressive stress values did not exceed the compressive strength values defined for the original footing stones and Moslawi marble. Also, the recommended rehabilitation methodology was proposed to enhance the structural characteristics of the dome, the original Moslawi marble columns, and the old stone footings under the marble columns. © 2023, Faculty of engineering, Cairo University.

关键词： Compressive strength

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How to incorporate climate change projections in the probabilistic assessment of civil structures

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Heron 2022年第2期67卷 97-120页

作者： Özer, I.E. Meinen, N.E. Steenbergen, R.D.J.M. TNO Department of Structural Reliability Delft Netherlands Faculty of Engineering University of Southern Denmark Odense Denmark Ghent University Faculty of Engineering and Architecture Department of Structural Engineering Ghent Belgium

Civil structures such as buildings, bridges, and flood defences, need to be designed to withstand extreme climatic actions during their entire design lifetime. Due to climate change, more extreme conditions are expected for those events that are relevant to civil structures (e.g. an increase in sea level or precipitation). Projecting the future climate is however an extremely challenging task which is highly subjected to uncertainties. This study investigates how these uncertainties can be included in the probabilistic design and assessment of civil structures. This is done by evaluating the uncertainties in global (IPCC, AR5) and regional (KNMI’14, the Netherlands) climate change projections. We identified that there is currently a discrepancy between the expectations of structural engineers with respect to uncertainty quantification on the one hand, and the limitations of climate science on the other hand. This leads to the following engineering challenges on (1) how to include or quantify uncertainties related to the climate change scenarios;(2) how to translate the available information about modelling uncertainties in climate models into the required quantitative information for traditional risk and reliability assessments;and (3) how to employ the provided climate change projections for the 30-year mean-values for the estimation of the required 50, 1000, or even 10.000 year extreme values. We discussed how these challenges lead to pragmatic modelling choices of engineers, and how this potentially leads to reduced structural safety. However, we believe that with a close collaboration between climate experts and engineers, many of these challenges can be addressed within the current limitations of science. © 2022 Delft University of Technology. All rights reserved.

关键词： Climate change

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Chloride diffusion in concrete with carbonated recycled coarse aggregates under biaxial compression

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Frontiers of structural and Civil engineering 2023年第4期17卷 637-648页

作者： Jingwei YING Weibeng WANG Jianzhuang XIAO Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education Guangxi UniversityNanning 530004China College of Civil Engineering and Architecture Guangxi UniversityNanning 530004China Guangxi Key Laboratory of Disaster Prevention and Engineering Safety Guangxi UniversityNanning 530004China Department of Structural Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

Chloride attack on concrete structures is affected by the complex stress state inside concrete,and the effect of recycled aggregates renders this process more *** the chloride resistance of recycled concrete in a complex environment via carbonization facilitates the popularization and application of recycled concrete and alleviates the greenhouse *** this study,the chloride ion diffusion and deformation properties of recycled concrete after carbonization are investigated using a chloride salt load-coupling *** results obtained demonstrate that the chloride ion diffusivity of recycled concrete first decreases and then increases as the compressive load increases,which is consistent with the behavior of concrete,in that it first undergoes compressive deformation,followed by crack *** enhances the performance of the recycled aggregates and reduces their porosity,thereby reducing the chloride diffusion coefficient of the recycled concrete under different compressive load *** variation in the chloride ion diffusivity of the carbonized recycled aggregate concrete with the load is consistent with a theoretical formula.

关键词： recycled concrete carbonated recycled coarse aggregate biaxial compression chloride diffusion stress level

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Use of the Fine Fraction from High-Quality Concrete Recycling as an Alternative Cement Substitute 1st

Use of the Fine Fraction from High-Quality Concrete Recyclin...

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1st International Conference on Net-Zero Built Environment: Innovations in Materials, Structures, and Management Practices, NTZR 2024

作者： De Brabandere, Laurena Grigorjev, Vadim Van den Heede, Philip Nachtergaele, Hannah Degezelle, Krist De Belie, Nele Magnel-Vandepitte Laboratory Department of Structural Engineering and Building Materials Faculty of Engineering and Architecture Ghent University Ghent Belgium Devagro Waregem Belgium

ISBN: (纸本)9783031696251

In order to meet the new demand for sustainability and lower carbon emissions for concrete, the production and recycling process has to be adapted. Regarding concrete recycling, the main focus in literature and industry is on the reuse of coarse aggregates. However, the recycling of concrete also generates a fine fraction. In this research, the fine fraction with size 0/2 is ground and studied as a partial cement replacement. First of all, the fines were characterized and their physical, chemical and mineralogical properties were determined. Preliminary tests on pastes and mortars with 0%, 5%, 10%, 15%, 20%, 25% and 30% cement replacement, such as isothermal calorimetry and strength tests, were performed. Based on these results, two concrete mixes were made: one reference mix with CEM I as a binder and natural aggregates and a concrete mix with 10% of CEM I replaced by concrete fines and a combination of natural and recycled aggregates. In this second mix, 27.8% of the sand and 100% of the coarse aggregates were replaced by recycled sand and recycled coarse aggregates. The concrete samples were tested on compressive strength, shrinkage and freeze–thaw resistance. The compressive strength of the green concrete was comparable to the strength of the reference concrete after 28, 56 and 90 days of curing. Concrete specimens containing the recycled fines and recycled aggregates had a higher drying shrinkage;however, a lower autogenous shrinkage was measured in comparison to the reference. Regarding durability, the green concrete had a lower freeze–thaw resistance compared to the reference. © The Author(s) 2025.

关键词： Concrete aggregates

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Annual reliability requirements for bridges and viaducts

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Heron 2024年第2期68卷 91-122页

作者： de Vries, R. Steenbergen, R.D.J.M. Maljaars, J. TNO Department of Structural Reliability Delft Netherlands Delft University of Technology Faculty of Civil Engineering and Geosciences Delft Netherlands Ghent University Faculty of Engineering and Architecture Ghent Belgium Eindhoven University of Technology Department of the Built Environment Eindhoven Netherlands

In the assessment of existing structures, such as bridges and viaducts, reliability requirements are used to decide if a structure is sufficiently safe, even when subjected to degradation. The reliability requirements may be expressed in different ways but should ultimately result in similar reliability performance of the structure. Most of the current assessment rules follow from a maximum allowable failure probability, depending on the reliability class, within a fixed period of time (the reference period: e.g. 15, 30, 50 or 100 years). A reliability requirement expressed using a fixed reference period fits the design of new (to be built) structures, but it is problematic for existing or temporary structures. In the case of existing structures, when for instance the design life has passed, the assessment should be flexible with respect to the expected or desired remaining life. Other factors, such as deterioration or changing loads, may also call for an assessment with a smaller time period since the failure rate could increase with time which makes a reliability requirement for a longer period less useful. Using fixed reference periods therefore could lead to suboptimal solutions where the economy and environment are unnecessarily hurt. Reliability requirements formulated on an annual basis provide a solution to this problem. In this article, reliability analyses of several typical bridges are performed to quantify the requirements in such a way that assessments based on annual reliability result in performance similar to the current practice. Special attention is paid to minimising and highlighting the cases where the annual requirements may lead to a trend that breaks with the current reliability requirements. © 2024 TU Delft. All rights reserved.

关键词： Fatigue of materials

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Performance of Calcium Nitrate as Accelerator for Cement Blended with Blast Furnace Slag 12

Performance of Calcium Nitrate as Accelerator for Cement Ble...

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12th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete, ICCM 2024

作者： Justnes, Harald Danner, Tobias Anfinsen, Elise Marie Rong Høye, Aleksandra Marie Munch-Ellingsen, Margrethe Torabzadegan, Mehrdad Department of Architecture Building Materials and Structures Norway Institute of Materials Technology Norwegian University of Science and Technology Norway Department of Architecture Materials and Structures Trondheim Norway Faculty of Engineering Department of Structural Engineering Trondheim Norway

ISBN: (纸本)9781641952507

The objective is to elucidate the effect of calcium nitrate CN on cement replaced with 50% blastfurnace slag (ggbs). The influence of 2 and 4% CN accelerator on hydration development of these binders were investigated by isothermal calorimetry, X-ray diffraction and thermogravimetry. The strength development of mortar with two different ggbs blended binders cured at 20°C was followed and the influence of CN discussed. Concrete with 50% of a third ggbs, 0, 2 and 4% CN and w/c = 0.46 was cured at +5°C and compressive strength development measured. CN led to lower mortar strength at 1 day at 20°C, but higher strength from 3 days onwards. Mortar with two different ggbs achieved the same strength at 7 and 28 days when added 4% CN. However, CN increased the 1-day strength of concrete cured at +5°C. Since ggbs is accelerated by high pH, the somewhat lower 1-day strength in mixes with CN is probably caused by the immediate precipitation of hydroxyl ions by calcium to portlandite leading to a lowering of the pH. CN led to more ettringite formation and AFm phases at 1-day sealed curing and the calcium hydroxide content was reduced. Reasons for calcium hydroxide reduction are discussed. © 2024 American Concrete Institute. All rights reserved.

关键词： Mortar

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Probing multi-physical process and deformation mechanism of a largescale landslide using integrated dual-source monitoring

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Geoscience Frontiers 2024年第2期15卷 417-432页

作者： Hong-Hu Zhu Xiao Ye Hua-Fu Pei Wei Zhang Gang Cheng Zi-Li Li School of Earth Sciences and Engineering Nanjing UniversityNanjing 210023China Department of Geotechnical Engineering Dalian University of TechnologyDalian 116024China Civil Structural&Environmental EngineeringSchool of Engineering and ArchitectureUniversity College CorkCorkIreland Department of Civil&Environmental Engineering Massachusetts Institute of TechnologyCambridgeMA 02139-4307United States

The implementation of isolated heterologous monitoring systems for spatially distant borehole deployments often comes with substantial equipment costs,which can limit the effectiveness of geohazard mitigation and georisk management *** address this,we have developed a novel monitoring system that integrates fiber Bragg grating(FBG)and microelectromechanical system(MEMS)techniques to capture soil moisture,temperature,sliding resistance,strain,surface tilt,and deep-seated *** system enables real-time,simultaneous data acquisition and cross-validation analyses,offering a costeffective solution for monitoring critical parameters in geohazard-prone *** successfully applied this integrated monitoring system to the Xinpu landslide,an active super-large landslide located in the Three Gorges Reservoir Area(TGRA)of *** resulting strain profile confirmed the presence of two shallow secondary sliding surfaces at depths of approximately 7 m and 12 m,respectively,in addition to the deep-seated sliding surface at a depth of28 *** lower secondary sliding surface was activated by extreme precipitation,while the upper one was primarily driven by significant changes in reservoir water levels and secondarily triggered by concentrated ***-slide piles have remarkably reinforced the upper moving masses but failed to control the lower *** gap between the pile heads and the soil amplified the rainwater erosion effect,creating a preferential channel for rainwater ***-physical measurements revealed a mixture of seepage-driven and buoyancy-driven behaviors within the *** study offers an integrated dual-source multi-physical monitoring paradigm that enables collaborative management of multiple crucial boreholes on a large-scale landslide,and contributes to the evaluation and improvement of engineering measures in similar geological settings.

关键词： Reservoir landslide Multi-physical process Integrated dual-source monitoring Fiber optic Extreme weather

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