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Defects in Concrete Elements: A Study of Residential Buildings of 30 Years and above in Onitsha Metropolis, Anambra State, Nigeria

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Journal of Building Construction and Planning Research 2022年第3期10卷 102-123页

作者： Chiamaka Ogochukwu Obiora Fidelis Okechukwu Ezeokoli Chritopher Chidi Belonwu Francisca Nkachukwu Okeke Department of Building Nnamdi Azikiwe University Awka Anambra State Nigeria Department of Building Niger Delta University Wilberforce Island Amasoma Bayelsa State Nigeria Department of Quantity Surveying Enugu State University of Science and Technology Agbani Enugu State Nigeria

Building defect is an issue in existing buildings that needs urgent tackling to prevent further problems. This study assessed the defects in concrete elements in residential buildings of 30 years and above in the Onitsha metropolis of Anambra State, Nigeria. Data collection instruments in the study include structured questionnaire, interviews, visual inspection/observations, archival records, recordings, photographs;and non-destructive testing of the concrete elements in an existing building in the study area. The population of this study constituted of the construction registered professionals and the existing buildings in study area. The sample for the study was based on the calculated sample size using Taro Yamani Formula. A total of 158 registered professionals were sampled from the population of 260. The questionnaires were purposively distributed to the registered professionals up to the required sample sizes of 158 and 129 questionnaires were properly filled and returned. The study used the SPSS and Microsoft Excel to analyze the data. The results were analyzed in percentages and figures using descriptive statistics and presented in the form of pie charts and tables. The finding of the study revealed that the causes and effects of structural defects on the concrete elements in existing buildings in the study area according to the rating are;exposed/corrosion of the embedded metals, faulty workmanship, overload and impacts, chemical attack, freeze-thaw deterioration, fire/heat, restraint to volume change. The visual observation revealed that the structural elements are characterized by heavy defects such as deep vertical, horizontal and diagonal cracks, exposed/ corrosion of the embedded metals, spalling of the concrete slabs. The existence of defects in the concrete members led to the low compressive strength of the concrete elements and the structural instability of the existing buildings as revealed by the non-destructive test. The non-destructive test result revealed that most of the tested concrete ele

关键词： Construction Industry Building Professionals Concrete Elements Defects Residential Buildings structural stability Non-Destructive Test Compressive Strength

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Influence of flange location on axial deformation stability of double-hat structure

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Journal of Beijing Institute of Technology 2012年第1期21卷 41-49页

作者：武雪原夏勇周青 State Key Laboratory of Automotive Safety and Energy Department of Automotive EngineeringTsinghua University

A new structural configuration with better impact stability for increasing energy absorbing efficiency is found. Based on finite element analysis, deformation modes of double-hat structure under axial impact loading are categorized to find the main reasons that affect deformation stability. It is revealed that, in a double-hat structure, the location of the flanges is highly related to the deform- ation mode and energy absorbing efficiency. Moving the flanges away from their traditional mid-loca- tion may result in more regular and stable deformation mode and achieve higher energy absorbing ef- ficiency. The flange offset value needs to be controlled within a certain range, otherwise, the doub- le-hat structure would tend to deform like a top-hat structure and the energy absorbing efficiency could be compromised. These findings and analyses lead to a new structural design configuration- asymmetric flange locations--for enhancing the deformation mode stability in double-hat structures.

关键词： double-hat structure structural stability plastic deformation energy absorbing effi- ciency

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The Golden Ratio Theorem: A Framework for Interchangeability and Self-Similarity in Complex Systems

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Advances in Pure Mathematics 2023年第9期13卷 559-596页

作者： Alessandro Rizzo Brescia Italy

The Golden Ratio Theorem, deeply rooted in fractal mathematics, presents a pioneering perspective on deciphering complex systems. It draws a profound connection between the principles of interchangeability, self-similarity, and the mathematical elegance of the Golden Ratio. This research unravels a unique methodological paradigm, emphasizing the omnipresence of the Golden Ratio in shaping system dynamics. The novelty of this study stems from its detailed exposition of self-similarity and interchangeability, transforming them from mere abstract notions into actionable, concrete insights. By highlighting the fractal nature of the Golden Ratio, the implications of these revelations become far-reaching, heralding new avenues for both theoretical advancements and pragmatic applications across a spectrum of scientific disciplines.

关键词： Conservation Law Self-Similarity Interchangeability Golden Ratio Complex Systems Dynamic Exchange structural stability Mathematical Modeling Theoretical Framework P vs NP Millennium Problem

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structural analysis of quarter-wave resonators in IMP

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Chinese Physics C 2013年第10期37卷 78-82页

作者：张聪贺守波王若旭张生虎何源赵红卫 Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

The taper-shaped superconducting quarter wave resonators with frequency of 80.5 MHz, β of 0.041 and 0.085 have been pre-researched. The radio frequency （RF） design of the cavities has been completed, and the structural design is also an important aspect which will be discussed in the following. The frequency shift caused by the etching effects of the surface treatment, the helium bath pressure and the Lorentz force, and the mechanical modes caused by the microphonic excitation have been anMyzed. The results show that the frequency variation from the Lorentz force is not serious and stiffening rings are explored aimed at decreasing the deformation brought by the helium pressure and microphonic excitation.

关键词： quarter-wave resonator structural stability etching effect Lorentz force detuning helium pressuredetuning mechanical vibration

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Reproducible and low-power multistate bio-memristor from interpenetrating network electrolyte design

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InfoMat 2022年第11期4卷 83-92页

作者： Bin Zhao Xuan Zhao QiLi Xiaochen Xun Tian Ouyang Zheng Zhang Zhuo Kang Qingliang Liao Yue Zhang Academy for Advanced Interdisciplinary Science and Technology Beijing Advanced Innovation Center for Materials Genome EngineeringUniversity of Science and Technology BeijingBeijingPeople's Republic of China Beijing Key Laboratory for Advanced Energy Materials and Technologies School of Materials Science and EngineeringUniversity of Science and Technology Beijin

Bio-memristor can address the inherent limitations of conventional memory components in artificial perceptual systems due to their biocompatibility with biological tissue.The actual deployment of bio-memristor is restricted by the lack of reproducibility,high power consumption,and insufficient storage capacity.Here,a reproducible and low-power multistate biomemristor is developed by designing the chitosan(CS)-reduced graphene oxide(rGO)interpenetrating network electrolyte.The interpenetrating network structure of the CS-rGO electrolyte reinforces structural stability and improves ionic conductivity.The bio-memristor equipped with CS-rGO active layer shows stable bipolar resistive switching up to 100 consecutive cycles,reproducible multistate storage with six different memory states,and low programming power of 9.4μW.The fabricated biocompatible CS-rGO device also exhibits deformation stability of memory operation over 103 bending cycles,high biocompatibility with HEK293 cells,and skin adhesion.This work provides an enlightening design strategy to develop highperformance bio-memristors for applications in artificial perceptual systems.

关键词： bio-memristor chitosan interpenetrating network electrolyte reproducible multistate structural stability

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BUCKLING AND POSTBUCKLING OF STIFFENED CYLINDRICAL SHELLS UNDER AXIAL COMPRESSION

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Applied Mathematics and Mechanics(English Edition) 1991年第12期12卷 1195-1207页

作者：沈惠申周频陈铁云 Shanghai Jiaotong University Shanghai

Buckling and postbuckling behaviors of perfect and imperfect, stringer and ortho/ropically stiffened cylindrical shells have been studied under axial compression. Based on the boundary la ver theory for the buckling oj thin elastic shells suggested in ref. [1], a theoretical analysis is presented. The effects of material properties of stiffenefs and skin, which are made of different materials, on the huckling load and postbuckling behavior of stiffened cylindrical shells have also been discussed.

关键词： structural stability buckling postbuckling stiffened cylindrical shell

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BUCKLING AND POSTBUCKLING BEHAVIOR OF ANTISYMMETRICALLY ANGLE-PLY LAMINATED COMPOSITE PLATES

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Applied Mathematics and Mechanics(English Edition) 1990年第12期11卷 1155-1165页

作者：沈惠申 Shanghai Jiaotong University Shanghai

The buckling and postbuckling behaviors of perfect and imperfect antisymmetrically angle-ply laminated composite plates under uniaxial compression have been studied by perturbation technique which takes deflection as its perturbation parameter.In this paper, the effects of in-plane boundary conditions, angles, total number of layers and initial geometric imperfection on the postbuckling behavior of laminated plates have been discussed.

关键词： structural stability buckling postbuckling laminated plate

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Discrimination conditions and process of water-resistant key strata

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Mining Science and Technology 2010年第2期20卷 224-229页

作者： WANG, Lianguo MIAO, Xiexing WU, Yu SUN, Jian YANG, Hongbo state key laboratory of geomechanics & deep underground engineering china university of mining & technologyxuzhou 221008china

Water-preservation mining is one of the most important parts of the ‘Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing passive prevention and governance of water disasters to active conservation and utilization of groundwater resources and thus obtaining coal and water simultaneously in mining.The concept of water-resistant key strata further enriches the content of the key stratum theory and provides a theoretical basis for water-preservation mining.In order to realize the idea of water-resistant key strata as a guideline in the design of water-preservation mining and engineering applications,the conditions for discrimination in the process of water-resistant key strata,we have presented a mechanical model,as well as its corresponding computer program,based on a large number of theoretical analyses and field measurements,as well as on a comprehensive consideration of the position,structural stability and seepage stability of key strata.Practical engineering applications indicate that this discrimination method and its corresponding computer program on water-resistant key strata are accurate and reliable and can satisfy the actual design needs of water-preservation mining and thus have instructional importance for water-preservation mining in mining areas lacking water.

关键词： water-resistant key stratum water-preservation mining structural stability seepage stability

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Commercial Application of Novel Heavy Oil Catalytic Cracking Catalyst HSC

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China Petroleum Processing & Petrochemical Technology 2017年第1期19卷 11-18页

作者： Zhang Zhimin Qilu Branch of SINOPEC Catalyst Co. LTD Zibo 255336

The commercial application of a novel RFCC catalyst HSC used in an 1.4 Mt/a RFCC unit at a refinery A was introduced. The application results show that in comparison with the base catalyst, the yield of dry gas and slurry was reduced, while the total liquid yield, gasoline yield and LPG yield increased by 1.34, 5.05 and 1.43 percentage points,respectively. The properties of the products showed no significant change while the anti-abrasion strength of the catalyst was relatively high. Based on the mid-term calibration test, the summary calibration test and the daily statistics of long term industrial application practice, the HSC catalyst features a strong conversion ability of heavy oil, a high gasoline yield, a satisfactory product distribution and a good selectivity.

关键词： heavy oil FCC catalyst industrial application structural stability

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First-principles calculations of structural,elastic and electronic properties of AB_(2)type intermetallics in Mg–Zn–Ca–Cu alloy

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Journal of Magnesium and Alloys 2013年第3期1卷 256-262页

作者： Pingli Mao Bo Yu Zheng Liu Feng Wang Yang Ju School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870PR China

Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculated lattice parameters were in good agreement with the experimental and literature values.The calculated heats of formation and cohesive energies shown that MgCu_(2)has the strongest alloying ability and structural stability.The elastic constants of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were calculated,the bulk moduli,shear moduli,Young's moduli and Poisson's ratio were derived.The calculated results shown that MgCu_(2),Mg_(2)Ca and MgZn_(2)are all ductile phases.Among the three phases,MgCu_(2)has the strongest stiffness and the plasticity of MgZn_(2)phase is the best.The density of states(DOS),Mulliken electron occupation number and charge density difference of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were discussed to analyze the mechanism of structural stability and mechanical properties.

关键词： Intermetallics First-principles calculation structural stability Electronic structure Elastic property

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