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Three-dimensional analysis of masonry vaults subjected to differential settlements

AIP Conference Proceedings 2021年第1期2343卷

作者： Nicola Grillanda Andrea Chiozzi Gabriele Milani Antonio Tralli 1Department of Architecture Built Environment and Construction Engineering (A. B. C.) Polytechnic University of Milan Piazza Leonardo da Vinci 32 20133 Milan Italy 2Department of Engineering University of Ferrara Via Saragat 1 44122 Ferrara Italy

In this paper, the three-dimensional analysis of masonry vaults subjected to differential settlements is presented. A representation through NURBS shell elements is followed. Elements are idealized as rigid blocks and jumps of displacement can occur only at interfaces. Starting from a known displacement at the external boundary, the overall displacement field is determined through standard linear programming formulations. A mesh adaptation governed by a Genetic Algorithm is then applied to find the shape of the mechanism deriving from the settlement. The procedure is here applied on a historical barrel vault and results are compared with previous experimental tests.

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Seismic performance assessment of a typified school building damaged during the 2019 Albanian earthquakes

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IOP Conference Series: Materials Science and engineering 2020年第1期989卷

作者： Marjo Hysenlliu Hüseyin Bilgin Polytechnic University of Tirana Department of Civil Engineering 1001 Tirana Albania EPOKA University Faculty of Engineering and Architecture 1032 Tirana Albania

This study presents the seismic performance evaluation of a typified masonry school building, Shkolla 9-Vjeçare '26 Nëntori', which was damaged by the recent earthquakes which hit Albanian territory on November 26, 2019. This building was constructed in 1985 by following the template school projects in Albanian construction practice. The current situation of the building was evaluated by considering the provisions of modern codes i.e. Eurocode 6, Eurocode 8 and Turkish building Code. Analytical model of the school building was developed using the experimental test results conducted on the brick units and mortar. Nonlinear static pushover analyses were executed to estimate the seismic capacity, the performance point, and the damage limit state levels. The performance based assessment rules were used for this objective. Deficiencies and weak points were identified by the detailed examination of the pushover curves. Results showed that selected school designed per pre-modern code is far from satisfying the desired criteria, suggesting that urgent response and necessary measures should be put into action.

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Strengthening of the reinforced concrete tank of anaerobic purification plants with the manufacture of biogas, damaged as a result of design and construction errors

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IOP Conference Series: Materials Science and engineering 2021年第1期1021卷

作者： A Kramarchuk B Ilnytskyy D Hladyshev O Lytvyniak Department of Building Constructions and Bridges Institute of Civil Engineering and Building System Lviv Polytechnic National University S. Bandera str. 12 79013 Lviv Ukraine Lviv Polytechnic National University Institute of Architecture and Design Department of Architectural Design and Engineering S. Bandera str. 12 79013 Lviv Ukraine Department of Civil Safety Viacheslav Chornovil Institute of Sustainable Development Lviv Polytechnic National University S. Bandera str. 12 79013 Lviv Ukraine

The defects and damages of bearing structures (walls, covering) of the solid-cast reinforced concrete tank were identified and detected using visual and instrumental testing. The actual reinforcement of the tank was determined and coordinated with designed reinforcement. Furthermore, the deformations were measured, the cracks opening in the walls and its depth in the concrete were detected and was also the strength quality of concrete was defined. During the year of the operation, the tank developed a considerable system of cracks in all lateral walls from technological loadings. At the same time, the width of the crack opening exceeded the limit values for reinforced capacitive structures (wk), which is equal to 0.1 mm. The walls lost tightness, the use of the structure in the technological process was suspended. Checking calculations of the design solutions was carried out for the elements of the tank on technological loadings in the software package LIRA to find the causes of the cracks opening and water penetration in the walls of the reinforced concrete tank. It was determined that the existing design solutions did not ensure the bearing capacity and the fracture strength of bearing reinforced elements of the tank and its spatial rigidity from technological loadings. Necessary reinforcement was defined by ensuring the strength and possible limitation of the width of the cracks opening. This article presents the technical solutions concerning the strengthening of repair bearing elements of reinforced concrete spatial frame of the existing structure. The external bandages (reinforcing steel 4d32A400C) and inner tension bars (stainless steel round pipes 168 x 5 mm) were used as the strengthening of the reinforced concrete tank.

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Effect of Water Content on Tensile Properties of Cement Mortar

Effect of Water Content on Tensile Properties of Cement Mort...

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2018 International Conference on Civil and Hydraulic engineering, IConCHE 2018

作者： Boxu, Meng Jinyu, Xu Chuanxin, Lou Chao, Gu Guang, Peng Department of Airfield and Building Engineering Air Force Engineering University Xi'an710038 China College of Mechanics and Civil Architecture Northwest Polytechnic University Xi'an710072 China

In order to study the effect of water content on the tensile properties of cement mortar, the "8" test method was used for the five water contents of the two mix ratios (saturation was 0%, 25%, 50%, 75%, and 100% respectively.) A total of 100 cement mortar specimens were subjected to a uniaxial tensile test. The test results show that the stress-strain curves of the cement mortar specimens are similar under different saturation, and the stress increases nonlinearly with the increase of the strain. After the peak strain is reached, the specimens are destroyed. The curve has no yield stage and shows the characteristics of brittle materials of the cement mortar;As the saturation increases, the tensile strength, peak strain and fracture toughness of the cement mortar specimens first decreased and then increased, and showed a linear relationship;the cement with a saturation of 50% mortar specimens have the lowest tensile properties. Compared with cement mortar samples with saturation of 0%, the tensile strength, peak strain, and fracture toughness were reduced by 40%, 24%, and 50%, respectively;the peak strain of cement mortar specimens with 100% saturation was the largest. The cement mortar specimens with a saturation of 0% increase by 24%;by comparing the tensile properties of cement mortar specimens at two different mix ratios (water-cement ratios of 0.55 and 0.45, respectively), it was found that the water-cement ratio was not the same. The effect of saturation on the tensile properties of cement mortar is similar, verifying the accuracy of the test results. © Published under licence by IOP Publishing Ltd.

关键词： Cements

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Fuzzy feature fusion and multimodal degradation prognosis for mechanical components

Fuzzy feature fusion and multimodal degradation prognosis fo...

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作者： Li, Xuejiao Ren, Yongmei Tan, Xiaoyong Department of Architecture and Civil Engineering Chongqing Telecommunication Polytechnic College Chongqing402247 China School of Management Chongqing Jiaotong University Chongqing China

Reliable degradation prognosis of mechanical components is very important for condition-based maintenance to improve the reliability and reduce the cost of maintenance. This paper reports the development of a fuzzy feature fusion and multimodal regression method for the degradation prognosis of mechanical components. Initially, the raw features from the vibration signals of the mechanical components are extracted. A degradation index is subsequently yielded by merging the obtained features through/using the fuzzy fusion technique. The ensemble empirical mode decomposition is then introduced to decompose the fusion index into several multimodal sub-series to acquire more detailed information. Extreme learning machines are established to predict the sub-series in different modes. The predicted results are obtained by integrating the multimodal sub-results. The reported approach was evaluated with real data from a rolling element bearing. Moreover, two peer models were imported to validate the effectiveness of the proposed method. The experimental results indicate that the reported approach is capable of erecting the degradation index reflecting the bearing degradation and that it had better performance in the remaining useful life prediction than the peer methods. © 2018 - IOS Press and the authors. All rights reserved.

关键词： Empirical mode decomposition

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Assessing the long-term structural changes of metakaolin geopolymers encapsulating pyrite cinder: environmental, microstructural and structure studies

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Sustainable Materials and Technologies 2025年 45卷

作者： Sanae Sbi Abdelilah Aboulayt Mohamed Ounacer Bouchaib Manoun Mohammed Sajieddine Said Mansouri Youssef Samih Nawal Semlal Waltraud M. Kriven Youssef Tamraoui Jones Alami Materials Science Energy and Nano-engineering Department MSN Mohammed VI Polytechnic University Ben Guerir Morocco Laboratory of Built Environment and Landscape LaBEL National School of Architecture of Tetouan Avenue Baghdad Touabel soufla 93040 Tetouan Morocco LCPME CNRS Université de Lorraine Nancy F-54000 France Rayonnement-Matière et Instrumentation FST Hassan First University of Settat 92600 Settat Morocco LGEM FST Sultan Moulay Slimane University BP 523 23000 Beni-Mellal Morocco National School of Applied Sciences BP 77 25000 Khouribga Morocco Corporate Sustainability & Innovation Office OCP S.A Casablanca Morocco Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

This study aimed to determine whether Fe-rich waste (pyrite cinder) can be structurally and environmentally stabilized in a metakaolin-based geopolymer matrix over long curing periods. The strength evolution, microstructural transformation, and leaching behavior of metakaolin (MK) blended pyrite cinder (PyC) geopolymer were investigated for up to 4 years of curing at 25 °C. The MK:PyC ratios were 100:0, 75:25, 50:50, and 25:75, activated by a combination of NaOH and Na 2 SiO 3 solutions. Phase evolution and microstructural reorganization by XRD, FTIR, and SEM-EDS indicated a partial crystallization of geopolymer amorphous gel into faujasite-Na zeolite over long-time curing (1–2 years). Strength evolution showed a correlation between PyC content and phase transformation. Mixtures with higher PyC contents generally exhibited lower compressive strength (around 3 MPa), which tended to be much lower after zeolite formation by approximately 90 %. Stabilization/solidification of the PyC at early- and long-age resulted in safe leaching levels of iron and heavy metals (Cu, As, Ba, Zn, Pb, Mn, and Cr), significantly below US-EPA standards. Fe investigation by Mössbauer spectroscopy indicated the possible incorporation of Fe 3+ in the tetrahedral network of geopolymer binder with PyC ≤ 50 wt%. However, following the amorphous phase transformation, some of the Fe 3+ ions were found to occupy the octahedral sites in the extra-framework positions of faujasite-Na.

关键词： Mossbauer spectroscopy

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Influence of contact area coefficient on the results of u-p formation dynamic equations of fluid-saturated porous media

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IOP Conference Series: Earth and Environmental Science 2021年第1期791卷

作者： Chaoqun Feng Pei Zhang Chengshun Xu Xiuli Du Chong Yue The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of Technology Beijing 100124 China School of Civil and Transportation Engineering Beijing University of Civil Engineering and Architecture Beijing 102616 China Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong China

The principle of effective stress is the keystone of modern physics, which becomes the basic difference between soil mechanics and general solid mechanics. Terzaghi's effective stress principle has been controversial since it was put forward, especially for the calculation of effective stress, many scholars have revised it from different aspects. The pore pressure is reduced in all different modified formulas, that is, the pore pressure need to be multiplied by a pore pressure factor. However, the variation of pore pressure factor has always been ignored because the reduction of pore pressure is very small. In this paper, the effective stress expression considering the contact area coefficient is modified to the u-p formation dynamic equation, and the influence of the change of contact area coefficient on the dynamic characteristics of soil is studied.

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A uniqueness result on detecting a prey in a spider orb-web

arXiv

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arXiv 2019年

作者： Kawano, Alexandre Morassi, Antonino Escola Politecnica University of São Paulo São Paulo Brazil Polytechnic Department of Engineering and Architecture Università degli Studi di Udine Udine Italy

We consider the inverse problem of localizing a prey hitting a spider orb-web from dynamic measurements taken near the center of the web, where the spider is supposed to stay. The actual discrete orb-web, formed by a finite number of radial and circumferential threads, is modelled as a continuous membrane. The membrane has a specific fibrous structure, which is inherited from the original discrete web, and it is subject to tensile pre-stress in the referential configuration. The transverse load describing the prey’s impact is assumed of the form g(t)f(x), where g(t) is a known function of time and f(x) is the unknown term depending on the position variable x. For axially-symmetric orb-webs supported at the boundary and undergoing infinitesimal transverse deformations, we prove a uniqueness result for f(x) in terms of measurements of the transverse dynamic displacement taken on an arbitrarily small and thin ring centered at the origin of the web, for a sufficiently large interval of *** Codes 35Q74, 74H45, 74J25 Copyright © 2019, The Authors. All rights reserved.

关键词： Inverse problems

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Corrigendum to "Release of toxic elements in fishpond sediments under dynamic redox conditions: Assessing the potential environmental risk for a safe management of fisheries systems and degraded waterlogged sediments" [J. Environ. Manag., Volume 255, 2020, 109778]

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Journal of environmental management 2025年 376卷 124481页

作者： Sabry M Shaheen Ali El-Naggar Vasileios Antoniadis Farahat S Moghanm Zengqiang Zhang Daniel C W Tsang Yong Sik Ok Jörg Rinklebe University of Wuppertal School of Architecture and Civil Engineering Institute of Foundation Engineering Water- and Waste-Management Laboratory of Soil- and Groundwater-Management Pauluskirchstraße 7 42285 Wuppertal Germany University of Kafrelsheikh Faculty of Agriculture Department of Soil and Water Sciences 33516 Kafr El-Sheikh Egypt. Electronic address: shaheen@uni-wuppertal.de. Department of Soil Sciences Faculty of Agriculture Ain Shams University Cairo 11241 Egypt. Electronic address: ali_elnaggar@agr.asu.edu.eg. Department of Agriculture Crop Production and Rural Environment University of Thessaly Greece. Electronic address: antoniadis@uth.gr. University of Kafrelsheikh Faculty of Agriculture Department of Soil and Water Sciences 33516 Kafr El-Sheikh Egypt. College of Natural Resources and Environment Northwest A&F University Yangling Shannxi 712100 China. Electronic address: zhangzq58@***. Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong China. Electronic address: dan.tsang@polyu.edu.hk. Korea Biochar Research Center O-Jeong Eco-Resilience Institute (OJERI) & Division of Environmental Science and Ecological Engineering Korea University Seoul 02841 Republic of Korea. Electronic address: yongsikok@korea.ac.kr. University of Wuppertal School of Architecture and Civil Engineering Institute of Foundation Engineering Water- and Waste-Management Laboratory of Soil- and Groundwater-Management Pauluskirchstraße 7 42285 Wuppertal Germany. Electronic address: rinklebe@uni-wuppertal.de.

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A FREQUENCY-DRIFT COMPENSATED CLOSED-FORM SOLUTION for STEREO RGB-D MAPPING 4

A FREQUENCY-DRIFT COMPENSATED CLOSED-FORM SOLUTION for STERE...

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4th ISPRS Geospatial Week 2019

作者： Tang, S.J. Zhu, Q. Chen, W. Wang, W.X. Li, Y. Darwish, W. Li, W.B. Research Institute for Smart Cities Shenzhen Key Laboratory of Spatial Information Smart Sensing and Services School of Architecture and Urban Planning Shenzhen University Shenzhen China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University Chengdu China Department of Land Surveying and Geo-Informatics Hong Kong Polytechnic University Hung Hom Hong Kong

In this work, we present a frequency-drift compensated (Fd-C) closed-form solution for stereo RGB-D SLAM. The intrinsic parameters for each sensor are first obtained with a standard camera calibration process and the extrinsic orientation parameters achieved through a coarse-to-fine scheme that solves the initial exterior orientation parameters (EoPs) from control markers and further refines the initial value by an iterative closest point (ICP) variant minimizing the distance between the RGB-D point clouds and the referenced laser point clouds. With the assumption of fix transformation between the frames with the same timestamp, we define one sensor as reference sensor and the other sensor as slave sensor and the slave frames can be mapped to the timeline of the references sensor. Rather than endow the camera pose of the nearest frame to the slave frames, we derive the accurate camera pose for slave frames in a spatially variant way. Therefore, the pose relations between the slave frame and the adjacent reference frame can be derived, which provided opportunity to use the more accuracy observations from multiple frames for better tracking and global optimization. We present the mathematical analysis of the iterative optimizations for pose tracking in multi-RGB-D camera cases. Finally, the experiments in complex indoor scenarios demonstrate the efficiency of the proposed multiple RGB-D slam algorithm. © Authors 2019.

关键词： Mapping

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