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It is of great theoretical significance to effectively reveal the energy driving-damage degradation-structural failure mechanism of rocks for the probability evaluation and prevention of rock burst in deep coal mines. Therefore, uniaxial loading and unloading tests of layered sandstones were conducted. Subsequently, the progressive failure process and stress–strain curves were obtained. Then, the evolution characteristics of strength, strain, energy, damage and macroscopic failure was characterized. Meanwhile, the damage proportion at each stage was quantified, and the linear damage deterioration law was obtained. Finally, the energy driving-damage degradation-structural failure mechanism was revealed. The results showed that: (1) increasing the unloading stress level did not necessarily reduce the bearing capacity, but the unloading effect could significantly affect the energy storage capacity; (2) there was the significant linear evolution relationship between the damage proportion and the unloading stress level under identical inclination angle in stages II and IV; (3) When the unloading stress level was over 0.7, the pre-peak structural adjustment behavior could strengthen the stability of post-peak structures and reduce the impact degree of rock burst. The conclusions could provide certain of theoretical basis for the prevention of rock burst in deep coal mines.HighlightsThe pre- and post-peak structural evolution stages belonged to the active and passive structural adjustment behaviors, respectively.When the unloading stress level was over 0.7, the pre-peak structural adjustment behavior could strengthen the post-peak structures stability.The linear damage degradation law was obtained, and the failure mechanism was revealed.

The significant joints, high in-situ stress—osmotic pressure coupling and excavation disturbances were prone to cause deep surrounding rock to undergo continuous excavation processes. It included the crack-initiation, -propagation, -nucleation, rib-spalling and roof-falling, collapse and instability, disaster appearing, corresponding to the disaster -incubation, -induction, -causation and -manifestation. The evolution processes restricted the coal mining efficiency. Therefore, the fluid–solid coupling mechanical tests considering the effects of confining pressures, excavation and bedding were conducted. Then, the permeability properties were characterized. The macroscopic- and microscopic- structural characteristics were clarified. Meanwhile, the fractal and chaotic characteristics of fracture structures were obtained. Subsequently, the structural failure mechanism was revealed. The research results were as follows: (1) The bedding played a significant driving role in the development, expansion and formation of the microscopic pore-cracks structures; (2) The higher the effective confining pressure was, the more complex the distribution characteristics of molecular fracture structures was, and the more significant the chaotic characteristics was; (3) Due to the effects of bedding buckling, water wedging, seepage water lubrication, tensile-shear combined and shear sliding friction, different bedding angles result in different macroscopic—microscopic—molecular structural failure mechanisms. These research results could help improve the prevention accuracy of underground disasters in coal mining. Graphical Abstract Article highlights The excavation unloading effect could change the brittle - ductility transform characteristics. The more the number of pore-cracks in the molecular surfaces was, the higher the porosity was not necessarily. The synthetic actions of bedding, excavation and confining pressure would influence fractals and chaotic properties.

An asphalt mastic has thixotropic characteristics that significantly influence its fatigue and healing performance. Therefore, understanding the thixotropy of an asphalt mastic is clearly of great importance. However, research in this area is still in the early stages. This study focuses on self-heating as one of the biasing performances of asphalt material by analyzing the viscosity, stress, and hysteresis loops the of asphalt mastics under cyclic shear loading. Twelve types of asphalt mastics fabricated with asphalt, as well as different types of mineral filler, were selected to examine thixotropy. In addition, the filler/asphalt ratio was examined via the hysteresis technique to analyze the hysteresis loop and the viscosity–shear rate. The thixotropic potential function was also studied from the energy viewpoint. The results show that asphalt mastics with different asphalt binders, mineral fillers, and filler volume fractions showed hysteresis loops for shear stress versus shear rate diagrams. With an increase in the loading times of the cyclic load, the area of the hysteresis loop gradually decreases, and the hysteresis area most likely features a relatively stable value. The thixotropy of the asphalt can be significantly reduced by adding filler, and different types of mineral filler can slightly influence the thixotropy. The viscosity decreases with an increase in the shear rate, and it gradually recovers with a decrease in the shear rate. The greater the filler/asphalt ratio, the greater the viscosity, and the faster the viscosity’s descent is with the prolongation of time. Due to the existence of a higher amount of filler content, the recovery of a viscosity crack is more difficult. For asphalt mastics with high filler/asphalt ratios, the thixotropic mechanism can be explained via particle agglomeration and the depolymerization theory. For asphalt mastics with low and medium filler/asphalt ratios, the thixotropic mechanism can be explained via the particle chain theory. The damage and recovery of the internal structure of an asphalt mastic can be characterized by the structural failure potential function and the structural recovery potential function, respectively.

Artificial intelligence (AI) has enabled several optimization techniques for structural design, including machine learning, evolutionary algorithms, as in the case of genetic algorithms, reinforced learning, deep learning, etc. Although the use of AI for weight optimization in steel and concrete buildings has been extensively studied in recent decades, multi-objective optimization for reinforced concrete (RC) and steel buildings remains challenging due to the difficulty in establishing independent objective functions and obtaining Pareto fronts. The well-known Non-Dominated Sorting Genetic Algorithm II (NSGA-II) is an efficient genetic algorithm approach for multi-objective optimization. In this work, the NSGA-II approach is considered for the multi-objective structural optimization of three-dimensional RC buildings subjected to earthquakes. For the objective of this study, two function objectives are considered: minimizing total cost and the probability of structural failure, which are obtained via several nonlinear seismic analyses of the RC buildings. Beams and columns’ cross-sectional dimensions are selected as design variables, and the Mexican Building Code (MBC) specifications are imposed as design constraints. Pareto fronts are obtained for two RC-framed buildings located in Mexico City (soft soil sites), which demonstrate the efficiency and accuracy of NSGA-II for structural optimization.

Modelling and Estimation of Damage in Structures is a comprehensiveguide to solving the type of modelling and estimation problems associated with the physics of structural damage. * Provides a model-based approach to damage identification * Presents an in-depth treatment of probability theory and random processes * Covers both theory and algorithms for implementing maximum likelihood and Bayesian estimation approaches * Includes experimental examples of all detection and identification approaches * Provides a clear means by which acquired data can be used to make decisions regarding maintenance and usage of a structure

Structural failures are one of the important phenomena which should be very important to dealt with. Structural failures occur then and causing heavy damage to both property and human lives. Structural elements include beam, column, slab etc. The failure of the horizontal load bearing member beam is considered. The beams of Eighteen members were casted; keeping three as control specimens and others grouped into Five groups. All specimens are subjected to Failure load and Five methods of retrofitting were done. After the curing period the retrofitted elements were tested for Ultimate load bearing capacity. The values are tabulated and compared. The best method regarding high load bearing strength and lowest deflection were found out.

Abstract The urgency of decarbonization calls for a deeper understanding of photovoltaic (PV) deployment in terms of planning, acquisition, and installation, and of the justification for policies targeting these aspects. So far, energy policy for PVs has focused on financial and information-oriented policies to enhance demand but has not explicitly focused on addressing the practical activities that enable deployment. The aim of this paper is thus to identify market failures, structural system failures, and transformational system failures associated with PV deployment and assess their implications for policy. The paper provides a review of literature on PV deployment revealing challenges at various stages of the PV adoption process; and based on a survey and interviews with building owners, construction companies, and installers in Sweden, we illustrate the systemic nature of failures in current PV deployment, suggesting the need for complementary policy interventions that address institutional rather than economic and informative support. We provide examples of policy explicitly addressing the tangible deployment of PVs. To correct for ‘market failures’, we suggest, for example, reviewer ratings on public platforms, since the selection of suppliers and installers turns out to be the most crucial step in the acquisition of PVs; to address ‘structural system failures’ we suggest, for example, capacity building within municipal organizations and improved methods for architectural integration of solar systems and guidelines for deployment in historic environments; to address ‘transformational system failures’ we suggest, for example, a legal framework supporting connection to the grid. Lay Summary We argue there is a need to rethink policy for the implementation of new energy technologies such as solar photovoltaic (PV). Policymakers should not only focus on increasing demand but also on addressing issues in the tangible deployment of new technologies. In this paper we assess market failures, as well as other failures associated with a transformative change, and review them as justifications for complementary policy interventions to accelerate the deployment of PVs. Graphical Abstract Graphical Abstract

A comprehensive guide to the application and processing of condition-based data to produce prognostic estimates of functional health and life.  Prognostics and Health Management provides an authoritative guide for an understanding of the rationale and methodologies of a practical approach for improving system reliability using conditioned-based.

This book provides answers to the following problems: how to identify the most probable critical failures; how to describe and use data-concerning materials that are either heterogeneous, time-variant, or space-variant; how to quantify the reliability and lifetime of a system; how to use feedback information to actualize reliability results; and how to optimize an inspection politic or a maintenance strategy. Numerous authors from public research centers and firms propose a synthesis of methods, both new and well-known, and offer numerous examples concerning dams, geotechnical study, and structures from nuclear and civil engineering.

This book provides a new, valuable approach to the consideration of risk in underground engineering projects constructed within rock masses. There are Chapters on uncertainty and risk, rock engineering systems, rock fractures and rock stress, the design of a repository for radioactive waste, plus two major case examples relating to the headrace tunnels and caverns for a hydroelectric project. The book is particularly timely given the current increasing emphasis on geo-engineering safety, accountability and sustainability. The book will benefit all who are concerned with rock engineering projects in civil, mining, geological and construction engineering worldwide.