Material Fatigue Research Articles

Preface to the theme issue 'physics-informed machine learning and its structural integrity applications'.

The issue focuses on physics-informed machine learning and its applications for structural integrity and safety assessment of engineering systems/facilities. Data science and data mining are fields in fast development with a high potential in several engineering research communities; in particular, advances in machine learning (ML) are undoubtedly enabling significant breakthroughs. However, purely ML models do not necessarily carry physical meaning, nor do they generalize well to scenarios on which they have not been trained on. This is an emerging field of research that potentially will raise a huge impact in the future for designing new materials and structures, and then for their proper final assessment. This issue aims to update the current research state of the art, incorporating physics into ML models, and providing tools when dealing with material science, fatigue and fracture, including new and sophisticated algorithms based on ML techniques to treat data in real-time with high accuracy and productivity. This article is part of the theme issue 'Physics-informed machine learning and its structural integrity applications (Part 1)'.

Main problems in the operation of metal gas discharge pipes

This paper considers the main problems of operation of metal gas discharge pipes on the example of research and survey work on the examination of building structures of the exhaust tower with three gas discharge trunks 180 m high, flue gas purification unit of the sintering shop of LLP "NDFZ" in Zhambyl region. Analysis of the actual technical condition, considered in this article exhaust tower with three gas discharge shafts, according to the results of the survey, its volume-planning and structural solutions, showed its generally unrepairable, due to the mass of characteristic critical and unacceptable damage to the load-bearing elements of the frame, physical fatigue of materials, significant corrosion wear of metal structures, which will require a significant amount of proposed repair and maintenance work to eliminate them. The conducted complex of researches has shown that the service life of chimneys built before the 1960s and after has practically expired. Repair or reconstruction of chimneys using previously mastered technologies and materials does not solve the issues of reliability improvement. Rational solutions to these problems are periodic technical expertise by highly specialized organizations and implementation on its basis of methods of overhaul of both gas-exhausting trunks and building structures and interface units, wide implementation of which will solve the problem of extending the life of chimneys.

Modelling of Peristaltic Pumps with Respect to Viscoelastic Tube Material Properties and Fatigue Effects

Peristaltic pump technology is widely used wherever relatively low, highly accurately dosed volumetric flow rates are required and where fluid contamination must be excluded. Thus, typical fields of application include food, pharmaceuticals, medical technology, and analytics. In certain cases, when applied in conjunction with polymer-based tubing material, supplied peristaltic flow rates are reported to be significantly lower than the expected set flow rates. Said flow rate reductions are related to (i) the chosen tube material, (ii) tube material fatigue effects, and (iii) the applied pump frequency. This work presents a fast, dynamic, multiphysics, 1D peristaltic pump solver, which is demonstrated to capture all qualitatively relevant effects in terms of peristaltic flow rate reduction within linear peristaltic pumps. The numerical solver encompasses laminar fluid dynamics, geometric restrictions provided by peristaltic pump operation, as well as viscoelastic tube material properties and tube material fatigue effects. A variety of validation experiments were conducted within this work. The experiments point to the high degree of quantitative accuracy of the novel software and qualify it as the basis for elaborating an a priori drive correction.

Laser shock peening regulating residual stress for fatigue life extension of 30CrMnSiNi2A high-strength steel

The improvement of material fatigue life has been a continuous pursuit in engineering. Laser shock peening (LSP) is an excellent processing method that can effectively enhance the service life of engineering materials. In this paper, the 30CrMnSiNi2A high-strength steel was treated with LSP to improve the fatigue life, respectively. The material's roughness has improved as a result of LSP treatment, and additional treatments have a more noticeable improvement than the energy density’s increase. The change in residual stress, however, presented a distinct pattern. There was not much difference between the laser treatment of once at 7.89 GW/cm2 and three times at 6.57 GW/cm2 in terms of compressive residual stress. The maximum hardness of the material surface was up to 589.8 HV under the combined effects of work hardening and compressive residual stress. In the fatigue life test of different loading stresses, the fatigue life of the treated samples was more than doubled compared with the untreated samples. The greatest life improvement occurred in high load fatigue testing. Combined with the analysis of fracture morphology, it could be found that the transfer of crack source from the surface to the interior caused by the gradient compressive residual stress is the reason for the increase in life.

Intracycle Active Blade Pitch Control for Cross-Flow Tidal Turbines Using Embedded Electric Drive Systems

Cross-flow tidal turbines (CFTTs) have proven advantages over horizontal axis turbines in terms of high power density per unit area, simplicity of design, and operation independence from inflow direction. However, they suffer from an unsteady flow regime which can comprise dynamic blade stall and thus problems of material fatigue or even failure. Active pitch control mechanisms on blade level have been shown to provide a potential solution, when continuously adjusting the pitching angle of each individual blade during the whole rotational cycle of the turbine.
 As part of the research of the OPTIDE project, in this study, electric drive systems embedded in the blades of a CFTT flume model are proposed aiming to realize an active pitch control with high efficiency and fast response. The blade embedded actuation allows for reasonable flow conditions. For full scaled on-site applications this is required to reduce hydrodynamic losses and to protect the actuators and electronics from the harsh environmental and operation conditions. Based on the expected hydrodynamic loads from numerical flow simulations (CFD), several types of actuators are considered. The first type has brushless DC motors installed at both sides of each blade. Along with a gear box with proper reduction ratio, the actuators are able to provide required torque within expected cycle period. The second type of actuator drives the blade directly, which always results in faster pitching action, higher drive efficiency, more accurate positioning of blades, as well as simpler structure. Specifically, the shaft of each blade is designed as the primary of a limited angle torque motor, while the blades are used as the secondary with magnets inside. To mitigate the potential saturation effect on the iron of the primary­, the blade can also be used as the primary, where there always exists much larger space for windings. In this case, the magnets are now located at the shaft. By doing this, it is expected to output larger torque in a wider range of pitching angle as compared with the original one, while almost the same power is required. An experimental test bench for a single blade with both types of actuators is built to verify their ability of a fast and accurate pitching control. This also lays the foundation of identifying the optimal pitching angle for the control and inhibition of dynamic blade stall at various flow conditions and blade positions within the rotational cycle of the turbines. After successful optimization and testing of the model scaled mechatronical design, the actuators will be up scaled for realistic applications.

Linear viscoelastic properties and fatigue S-VECD based evaluation of polymer-modified asphalt mixtures

Direct tensile fatigue tests associated with the simplified continuous damage viscoelastic model (S-VECD) have proven to be an effective tool for evaluating fatigue in asphalt materials. Thus, this study evaluated the fatigue damage of asphalt mixtures modified by the addition of polymer based on the results of the direct tensile fatigue test using the S-VECD model. Three asphalt mixtures were produced: a control asphalt binder with 50/70 penetration, a polymer-modified styrene-butadiene-styrene (SBS) asphalt binder, and a mixture produced with a modified asphalt binder (composed of 98.38% control + 1.26% Ethylene Methyl Acrylate and Glycidyl Methacrylate (EMA-GMA) + 0.21% High-Density Polyethylene (HDPE) + 0.15% Polyphosphoric Acid (PPA116%)). The binders were evaluated for physical and rheological properties, and fatigue using the Linear Amplitude Sweep (LAS) test, applying the S-VECD model. Asphalt mixtures were evaluated for stiffness using tensile strength, resilient modulus and flow number tests. The viscoelastic linear behaviour (LVE) was characterized based on the dynamic modulus test and the fatigue performance was evaluated from the uniaxial direct traction test with the application of the S-VECD viscoelastic damage model. The results of the LAS test indicated that the modified binder presented the best fatigue performance, being classified according to the binder fatigue factor (FFB) as excellent. Mixtures with binders modified by polymers showed the highest values in mechanical performance tests. As for the LVE behaviour, the mixture with the modified binder showed the expected behaviour, with higher dynamic modulus values at high temperatures (low reduced frequencies), and the lowest modulus values at lower temperatures (high reduced frequencies). In addition, for the entire spectrum of frequencies and temperatures, the modified mixture presented the lowest values of phase angle, indicating more elastic and less viscous behaviour. From the direct tensile test, based on the GR failure criterion, the modified mixture showed better fatigue performance, with a higher value of the Fatigue Factor of the Mixture (FFM). Based on the DR failure criterion, from the Sapp damage capacity, mixtures with polymers were classified with the best performances concerning fatigue. Therefore, the use of polymer-modified binders promoted asphalt mixtures with better fatigue damage performance.

A Fatigue Method in the Tension-Compression Axial Stress Control Test of Automotive Sheet Steel

Abstract Focused on the common problem of easy buckling of specimens in the tension-compression axial stress control fatigue test of automobile sheet steel, a stress fatigue test method for thickness less than 2.5 mm was proposed. For two kinds of automobile sheet materials with different strength levels and thicknesses, fatigue specimens with different widths of test section, parallel lengths, and fillet radii are designed. Without the anti-buckling device, high-cycle fatigue tests with a stress ratio Rs = −1 at different stress levels were carried out, and the shape and size of the fatigue specimens of automobile sheet materials were determined by the number of fatigue life cycles of specimens with different sizes under the same stress cycle form. The results show that for automobile sheet steel with a thickness of 1.0–2.5 mm, the recommended sizes of the uniform-gauge fatigue specimens are width of test section w = (1–3) t, parallel length Lp = (1–3) w, and fillet radius r = (3–10) t. For automobile sheet steel with a thickness less than 1 mm, because the time-displacement curve jitters during the test, it is recommended to install an anti-buckling device, specifically the anti-buckling device with mortise and tenon structure by self-design and with a flattop structure recommended by ISO 1099-2017, Metallic Materials—Fatigue Testing—Axial Force-Controlled Method.

Thermal-mechanical-equivalent fatigue load method for mechanically fastened Hybrid-material structures

It is difficult to verify the fatigue performance of mechanically fastened hybrid-material structures under the complex environment-load spectrum. A thermal–mechanical-equivalent fatigue load method was proposed, so that the structure has the same fatigue damage distribution under the equivalent load and the original thermal–mechanical load. By considering the influence of environmental temperature on the structural fatigue performance and the dispersion of material fatigue property, the calculation model for the fatigue damage distribution of fastened structure was established. The equivalent load could be determined according to the designed tolerance value of distribution difference. The effectiveness of method was verified by 7050-T7451 aluminum alloy/CFRP laminate plate three-bolt single-lapped hybrid fastened specimens.

Surface integrity optimization for ball-end hard milling of AISI D2 steel based on response surface methodology.

This study focuses on systematically revealing how cutting parameters influence the surface integrity of ball-end hard milled surface of AISI D2 steel and proposing optimization scheme from surface integrity, wear resistance and fatigue resistance perspective based on response surface methodology respectively. Results can be summarized into three aspects. Firstly, radial depth of cut with percent contribution ratio (PCR) 62.05% has a decisive influence on surface roughness, followed by spindle speed 13.25% and feed per tooth 6.63%. The work hardening degree was raised from 12.5% to 38.4% when spindle speed changed from 8000 rpm to 2000 rpm. Spindle speed and radial depth of cut are the most significant factor influencing residual stress. The PCR of spindle speed and radial depth of cut reached 73.47% and 18.63% for residual stress in feed direction, 47.11% and 37.51% in step-over direction, respectively. High residual compressive stress can be generated by lowering spindle speed and radial depth of cut benefiting from the aggravated squeeze between ball-end milling cutter and workpiece. Secondly, too small feed per tooth or too small radial depth of cut should be avoided from wear resistance point because though the surface microhardness can be improved, the surface quality will also be deteriorated. The combination of high spindle speed, small feed per tooth together with small radial depth of cut can meet the wear resistance and the machining efficiency requirement. Finally, a medium-sized cutting parameter combination should be adopted to realize satisfying material removal rate and fatigue resistance. This study can be used to guide the selection of cutting parameters during ball-end milling of hardened AISI D2 steel for dies/molds manufacturing industries.

Notch Fatigue Life Research Based on Critical Distance Theory

Orthotropic anisotropic steel bridge panels are widely used in civil engineering due to their advantages of light deadweight, high ultimate bearing capacity, and wide range of applications. However, their fatigue problem is serious, and the fatigue-resistant design of the steel box girder diaphragm curved cutout is still difficult. In order to effectively predict the fatigue life of this typical fatigue-susceptible detail, a fatigue test of the specimen with curved notched segments of the diaphragm was carried out. ABAQUS 2016 version finite element analysis software was used to establish three kinds of finite element simplified models of the fatigue specimens with curved notches, and the laws of the influence of different notch radii on the fatigue life of the specimens were studied. Through the finite element solution of the three arc notch specimen models with different radii under the tensile load of 50 kN their respective principal stress distributions were obtained. The critical distance theory was introduced to analyze the characteristic stresses in the stress concentration area of the arc notch, and the point method and line method were used to calculate the characteristic stresses. The fatigue life prediction models of three kinds of notched components were established by combining the material fatigue limit and FE-safe life results. The results show that the point method is more conservative than the line method; no matter if the point method or the line method is used, the characteristic stress and the notch radius are inversely proportional to each other, and it is beneficial for the fatigue life of the structure to appropriately increase the notch radius. The fatigue prediction model of steel box girder diaphragms with curved notches based on the critical distance theory is of high accuracy, which is basically consistent with the test results, verifying the feasibility of the critical distance theory in the fatigue life prediction of notched specimens, and providing a reference for the fatigue life assessment of similar steel structures.

Reconsidering the Role of Fatigue Irregular Testing in Scientific Conclusions About the Fatigue Limit

Aim. We suggest a method of using the fatigue test in case of irregular loading for studying the key subject matters related to material fatigue, specifically those to do with fatigue limit. It is important to know the fatigue limit characteristic in order to speed up tests; in order to ensure stable and reliable servicing of machines.Methods. Comparative examinations in cases of block and random loadings enable researchers to make corresponding conclusions without excessively extending the duration of tests and without recurring to supersonic frequency tests that are to a certain degree controversial. An example of applying the proposed method is given. The second stage of fatigue, specifically the crack propagation stage, is also considered. The key idea is similar. Testing under irregular loading allows making conclusions regarding the maximum among small amplitudes that do not cause damage.Conclusions. The proposed method allows using special testing methods to obtain information that is valuable to engineers and researchers. The tests are also closer to the field conditions of machinery operation.

Utilizing Dynamic Analysis in the Complex Design of an Unconventional Three-Wheeled Vehicle with Enhancing Cornering Safety

Current trends in the transportation industry prioritize competitive rivalry, compelling manufacturers to prioritize concepts such as quality and reliability. These concepts are closely associated with public expectations of safety, vehicle lifespan, and trouble-free operation. However, the public must recognize that a vehicle weighing several hundred kilograms, moving at a non-zero speed, only contacts the road surface through a few points (depending on the number of wheels), each no larger than a human palm. Therefore, it is imperative to operate the vehicle in a manner that optimizes the behavior of these contact points. There are situations where drivers find themselves requiring dynamic vehicle handling, often unpredictable with a high degree of uncertainty. Rapid changes in direction become necessary in these cases. Such maneuvers can pose a significant risk of rollover for three-wheeled vehicles. Hence, the vehicle itself should contribute to increased ride safety. This paper presents key findings from the development of an unconventional three-wheeled vehicle utilizing the delta arrangement. Rollover safety for three-wheeled vehicles is currently well-managed, thanks to the utilization of electronic or mechatronic systems in delta-type vehicles to enhance stability. However, these systems require additional components. In contrast, the proposed control system operates solely on a mechanical principle, eliminating operational costs, energy consumption, maintenance expenses, and similar factors. The study also explores the absence of equivalent suspension and steering systems for front-wheel steering. Such designs are lacking in both practical applications and theoretical realms. Analytical and simulation calculations are compared in this study, highlighting the effectiveness of the newly proposed control system in enhancing stability and safety compared to conventional front-wheel suspension systems. Simulation programs provide more realistic results than analytical calculations due to their ability to account for dynamic effects on vehicle components and passengers, which is practically unfeasible in analytical approaches. Furthermore, this study focuses on investigating the fatigue life of material frames subjected to dynamic loading, which is a crucial aspect of ensuring safety. It is essential to have various testing devices to examine the fatigue life of materials under both uniaxial and multiaxial loading conditions. However, obtaining experimental results for fatigue life measurements of specific materials, which can be directly applied to one’s research, poses significant challenges. Hence, the proposed testing device plays a vital role in measuring material fatigue life and advancing the development of unconventional transportation methods. The information about the original testing device aligns perfectly with the article’s emphasis on dynamic analysis. The ultimate objective of all these efforts is to put the vehicle into practical operation for commercial utilization.

Resilin in Insect Flight Systems

AbstractCompared to wingless insects, pterygote insects profit from numerous wing‐related benefits including a wider distribution range, the exploitation of various food resources and the escape from water‐ or land‐confined predators. In order to maintain the wings´ functionality, the wing design and resistance to material fatigue are of key importance. This is even more essential for survival when considering that wings are used for millions of wing beat cycles but cannot be repaired and do not contain inner muscles so that their aerodynamic performance is mainly based on passive, structure‐based wing deformations. One of the components serving this purpose is the endowment of certain wing components with the elastomeric protein resilin building stable and complex material composites with the tanned cuticle. Resilin endows the respective structures with, e.g., higher flexibility and compliance and enables elastic energy storage. In this study, the occurrence of resilin in the insect flight system is reviewed based on previous studies of several insect orders including Odonata, Orthoptera, Hymenoptera, Coleoptera, Dermaptera, and Diptera, and the function of resilin is discussed with reference to the respective structures.

Application of machine learning models for estimating the material parameters for multiaxial fatigue strength calculation

AbstractThis paper deals with a practical task of estimating missing material fatigue strengths required for the evaluation of multiaxial fatigue strength criteria, knowing other static or fatigue material parameters. Instead of searching for various analytical equations describing the dependencies between different material parameters, several machine learning models implemented in the caret R package are used here. The dataset used to train and test these models is based on the FatLim dataset with different material parameters, which has been redesigned for this new purpose. It is demonstrated that substantially more data points, such as were available in this study, are needed to achieve the goal set here. Although the results obtained at the current scale may be improved by the addition of new data points, the best performance of the random forest model rf and the worst performance of the pcr model are evident.

Centrifugal and gyroscopic effects on dynamic response of rotating cantilever beams under step loading

In this paper, a simplex finite element model for beams (FEMB) with a complete formulation is presented to study the dynamics of rotating cantilever beams subjected to distributed external loads. In our approach, the finite element method (FEM) and Timoshenko's beam theory is used. We will, particularly, examine the centrifugal and gyroscopic effects on the linear vibration of a rotating cantilever beam in stationary regime. In this model, extension, bending, and torsion degrees of freedom (DOF) are combined using a parameterization of the 3D motion of the beam by Euler's three-angle sequence. That allows identifying all the terms of the gyroscopic coupling in a more compact equations system. To ensure convergence, a sufficient number of finite elements are required in this model. The considered beam in the numerical simulation is pre-twisted and linearly tapered with a rectangular section. Results show that the dynamic centrifugal effect decreases the natural frequencies of the beam. Furthermore, the gyroscopic coupling induces rapid extension and torsion beatings when the beam undergoes a step bending load. Without damping, these beatings can persist and cause material fatigue.

Numerical Analysis and Experimental Investigation of High Cycle Fatigue Behavior in Additively Manufactured Ti–6Al–4V Alloy

Additive Manufacturing (AM) of the Ti–6Al–4V alloy has gained significant importance across various industries, including biomedical, aerospace, cellular, and land vehicle applications, due to its numerous benefits. The certification of performance and reliability of AM materials, particularly for critical applications, heavily relies on evaluating fatigue strength. In this study, a numerical analysis based on the finite element method is presented to predict the High Cycle Fatigue (HCF) behavior of AM Ti–6Al–4V alloy. The investigation focuses on exploring the sensitivity of material fatigue life to surface roughness and Ultimate Tensile Strength (UTS). Uniaxial tensile and High Cycle Fatigue (HCF) tests were conducted on Ti–6Al–4V alloy samples extracted from rectangular walls manufactured using the Laser Metal Deposition (LMD) process. The walls were surface machined prior to sample extraction. Porosity and surface roughness measurements were performed on the samples. Numerical simulations of the HCF tests were carried out, considering various surface roughness ranges and UTS values. The numerical results were then compared to experimental data. The findings consistently demonstrated that higher surface roughness led to a shorter fatigue life, while higher UTS values resulted in a longer fatigue life. The numerical solutions aligned with the experimental results, indicating the efficacy of the finite element method in predicting the fatigue behavior of AM Ti–6Al–4V alloy. These insights contribute to a better understanding of the relationship between surface roughness, UTS, and fatigue life of Ti–6Al–4V alloys manufactured by AM.

Non-destructive testing of fiber-reinforced composites by terahertz method

Fiber-reinforced composites are materials that are increasingly replacing metals in many construction solutions. Damage to the composite structure may occur both as a result of technological errors in the production phase and during operation as material fatigue or as a result of an impact by a foreign body. The specificity of defects that occur in fiberreinforced composites results in the development of non-destructive testing methods that enable the detection of these defects. One of these methods is the use of terahertz radiation. Terahertz radiation penetrates well through non-metallic materials. It can therefore be used for non-destructive testing, especially of composites reinforced with glass and aramid fibers. The terahertz band has been known for many years, but interest in the use of terahertz radiation in non-destructive testing has only recently emerged. This is due, among others, to the availability of sources of terahertz radiation of appropriate power enabling these tests. The radiation source is an important element of nondestructive testing with active methods that are most often used in this type of testing. In non-destructive testing, the terahertz radiation range from 100 GHz to 300 GHz is most often used. In this paper we present the results obtained using the transmission terahertz method.

Mechanical fatigue testing in silico: Dynamic evolution of material properties of nanoscale biological particles

Biological particles have evolved to possess mechanical characteristics necessary to carry out their functions. We developed a computational approach to "fatigue testing in silico", in which constant-amplitude cyclic loading is applied to a particle to explore its mechanobiology. We used this approach to describe dynamic evolution of nanomaterial properties and low-cycle fatigue in the thin spherical encapsulin shell, thick spherical Cowpea Chlorotic Mottle Virus (CCMV) capsid, and thick cylindrical microtubule (MT) fragment over 20 cycles of deformation. Changing structures and force-deformation curves enabled us to describe their damage-dependent biomechanics (strength, deformability, stiffness), thermodynamics (released and dissipated energies, enthalpy, and entropy) and material properties (toughness). Thick CCMV and MT particles experience material fatigue due to slow recovery and damage accumulation over 3-5 loading cycles; thin encapsulin shells show little fatigue due to rapid remodeling and limited damage. The results obtained challenge the existing paradigm: damage in biological particles is partially reversible owing to particle's partial recovery; fatigue crack may or may not grow with each loading cycle and may heal; and particles adapt to deformation amplitude and frequency to minimize the energy dissipated. Using crack size to quantitate damage is problematic as several cracks might form simultaneously in a particle. Dynamic evolution of strength, deformability, and stiffness, can be predicted by analyzing the cycle number (N) dependent damage, [Formula: see text] , where α is a power law and Nf is fatigue life. Fatigue testing in silico can now be used to explore damage-induced changes in the material properties of other biological particles. STATEMENT OF SIGNIFICANCE: Biological particles possess mechanical characteristics necessary to perform their functions. We developed "fatigue testing in silico" approach, which employes Langevin Dynamics simulations of constant-amplitude cyclic loading of nanoscale biological particles, to explore dynamic evolution of the mechanical, energetic, and material properties of the thin and thick spherical particles of encapsulin and Cowpea Chlorotic Mottle Virus, and the microtubule filament fragment. Our study of damage growth and fatigue development challenge the existing paradigm. Damage in biological particles is partially reversible as fatigue crack might heal with each loading cycle. Particles adapt to deformation amplitude and frequency to minimize energy dissipation. The evolution of strength, deformability, and stiffness, can be accurately predicted by analyzing the damage growth in particle structure.

Investigation of GRC Retrofitting Effect on Masonry Dome Using FEM

Historical buildings are the cultural heritage of the world. Preservation of historical buildings is important in the past and today. In particular, material fatigue, environmental vibration effects and natural disasters that occur over time cause great damage to historical structures. It is thought that many historical buildings will not reach the next years due to neglect. In order to prevent this situation, historical buildings should be maintained and strengthened if necessary. In addition, historical buildings should have sufficient stiffness to prevent collapse against pre-disaster situations. Masonry domes are often seen in historical buildings. Many masonries dome historical structures are frequently encountered today. In order for masonry dome in historical building to be transferred to the future, care should be taken and they may need to be strengthened periodically, especially after disasters. For all these reasons, in this study, the GRC retrofitting method, which is one of the retrofitting methods of buildings, is mentioned. Thus, the effect of the GRC retrofitting method applied on an exemplary historical masonry dome on modal parameters has been demonstrated. In this comparative study, it was observed that the stiffness of the masonry dome increased with the GRC retrofitting method. As a result of this study, it is suggested to retrofitting masonry dome with the GRC retrofitting method, taking into account the state of the historical building and environmental factors.

Seismic Strengthening of Stone Barrel Vault Structures by Foam Concrete

Historical buildings are the cultural heritage of the world. Preservation of historical buildings is important in the past and today. In particular, material fatigue, environmental vibration effects and natural disasters that occur over time cause great damage to historical structures. It is thought that many historical buildings will not reach the next years due to neglect. In order to prevent this situation, historical buildings should be maintained and strengthened if necessary. In addition, historical buildings should have sufficient stiffness to prevent collapse against pre-disaster situations. Stone barrel vaults are one of these historical cultural heritages. Many stone barrel vault type historical structures are frequently encountered today. In order for stone barrel vaults to be transferred to the future, care should be taken and they may need to be strengthened periodically, especially after disasters. For all these reasons, in this study, the foam concrete method, which is one of the retrofitting methods of buildings, is mentioned. Thus, the effect of the foam concrete method applied on an exemplary stone barrel vault on modal parameters has been demonstrated. In this comparative study, it was observed that the stiffness of the stone barrel vault increased with the foam concrete method. As a result of this study, it is suggested to retrofitting the stone barrel vault with the foam concrete method, taking into account the state of the stone barrel vault and environmental factors.