Damage Analysis Of Structures Research Articles

Lightning damage analysis of composite bolted joint structures based on thermal-electrical-structural simulation

To analyze the impact of connection behavior on lightning-induced ablation damage in composite bolted joints, this paper analyzes contact properties based on thermoelectric characteristics and develops a lightning ablation damage model for composite interference joint structures. A preliminary analysis of the electrothermal conduction process in the interference-fit composite joints clarifies the influence of connection behavior on lightning damage. The results indicate that a skin effect occurs near the fastener-to-CFRP interface, and both Joule heating and conductive heat significantly affect the temperature distribution in the composite bolted joint structure. A lightning current impact test was also conducted for validation and comparison. Quantitative comparisons show that the predicted in-plane damage aligns well with the experimental results, with an error of 7.37%, while the difference in thickness direction damage is more significant, with an error of 40.02%. Furthermore, the analysis of ablation damage characteristics reveals that the most severe damage occurs in the lower-middle region of the CFRP thickness due to the combined effects of interference damage and bolt preload, while damage in other areas is suppressed.

Damage Analysis of 3D Masonry Structures under Explosion Shock Waves Based on the CDEM

Damage Analysis of 3D Masonry Structures under Explosion Shock Waves Based on the CDEM

Damage analysis and mechanical performance evaluation of frame structures in recycling

Research on the recycling of space frame structures is beneficial to reduce the waste of resources and has important engineering application prospects. Repeated disassembly tests were carried out on a full size space frame structure with bolt-ball joints. The maximum number of cycles was 3. The test results showed that with the increase of the number of cycles, the damage of joints and tubes gradually increased, the phenomenon of false tightening increased, and the construction efficiency decreased. After three cycles, the damage of high-strength bolts accounted for 16.56 % and the damage of steel tubes accounted for 5 %. Due to the component damage and construction deviation, the deformation and stress of the structure after unloading could not be restored to that before loading. However, within three cycles, the overall displacement and stress of the frame structure under general roof loads were almost not affected by component damage and construction deviation. Furthermore, the distribution pattern of displacement and stress was independent of the number of cycles. The maximum mid-span displacement of the structure was about 80 mm and the maximum difference of the overall stress level was within 10 MPa. Finally, according to the test results, the relevant engineering suggestions for the recycling of space frame structures were put forward.

Reflections on the Decay Mechanisms of Half-Timbered Walls in Traditional Spanish Architecture: Statistical Analysis of Material and Structural Damage

Knowledge on the state of conservation and vulnerability of traditional techniques when faced with the most common degradation phenomena is vital in order to propose the most suitable conservation and maintenance actions. This article presents the systematic review of 1218 half-timbered walls found throughout Spain, enabling the identification of a total of 27 material lesions, classified by atmospheric, biological or anthropic origin, and 9 structural lesions due to stress or excessive deformation. Their qualitative and quantitative analysis has focused on the frequency of the individual lesions and the possible correlation with different constructive characteristics, such as the materials used, the geometry of the framework and the presence of plinths, eaves and protective rendering. Almost the entire sample presents some degree of material degradation, mostly atmospheric lesions of limited severity, such as superficial atmospheric erosion and chromatic alteration and dehydration of the timber. In terms of structural lesions, half-timbered walls are seen to be more vulnerable to this type of deformation. Considering the risk of loss affecting all traditional architecture, it becomes particularly important to promote the continued maintenance of half-timbered walls in order to reduce the influence of material lesions caused by atmospheric agents. Subsequently, suitable criteria for intervention are established in order to reduce the effect of anthropic lesions and structural degradation phenomena, particularly linked to a lack of maintenance and modifications of anthropic origin.

Seismic Damage and Disaster Reduction Analysis of Building Structures along the Surface Rupture Trace Line of Strong Earthquakes

Seismic Damage and Disaster Reduction Analysis of Building Structures along the Surface Rupture Trace Line of Strong Earthquakes

Comparative analysis of blast load transfer and structural damage in multi-cabin structures during air and underwater explosions

This study presents comprehensive experimental and numerical findings regarding the impact of the fluid medium on blast load transfer and structural damage mechanisms in multi-cabin structures subjected to air and underwater explosions. The experiments demonstrated that the structure primarily underwent a comprehensive dynamic response during an air explosion. In contrast, underwater explosions induced severe localized damage, with fluid properties significantly influencing the shockwave intensity. The observed plastic deformation, shear tearing of the structure, and shock wave characteristics in the experiment were successfully predicted through numerical simulations. Additionally, the numerical simulation unveiled distinct mechanisms of pressure changes in the cabin, attributing air and underwater explosions to transmitted pressure waves and compression shocks of the outer plate, respectively. The high-intensity shock waves generated by underwater explosions and bubble loads sequentially impacted the structure, resulting in more pronounced structural damage compared to the weaker shock wave effect of an air explosion. This study provides valuable insights for comprehending and predicting the response of multi-cabin structures in diverse explosion scenarios.

Study on load distributing function of square slab surface under the action of underwater close‐in blast loading

AbstractThe mode and magnitude of the blast load are the main cause of damage to the structure. Most current studies have simplified the blast load into a bilinear form that differs greatly from the actual time history curve and is applied directly to the structure, avoiding the fluid–solid coupling interaction between the water fluid and the structure. The simplified blast load for near‐explosion or internal explosion will bring a big error to the calculation results. To quickly determine the load on the structure surface under the action of underwater near the explosion, this study studies the interaction between water hammer wave and structure through the verified full coupling model, and puts forward the explosion load distribution function on the square plate surface under the action of underwater explosion, and establishes a simplified prediction formula for the explosion load parameters (peak pressure and positive reflection impulse) at the center of the plate surface, using these formulas, a general method for constructing the explosion load at any point on the structural surface is proposed, which lays a foundation for subsequent structural damage and failure analysis.

New Baseline Correction Method for Near-Fault Ground-Motion Records Based on Continuous Wavelet Transform

Abstract On 6 February 2023, a magnitude 7.8 earthquake struck south-central Türkiye. It was followed by many aftershocks, the largest of which was a magnitude 7.5 aftershock. This earthquake caused considerable loss of life and property. Numerous near-fault ground-motion records were collected during the 2023 Türkiye earthquake. Most existing baseline correction methods for near-fault ground motions disregard the commonly used filtering techniques due to their potential elimination of actual permanent displacement. To address this, a new automatic baseline correction method is proposed based on the continuous wavelet transform, which incorporates filtering while preserving permanent displacement. This method is compatible with existing filtering techniques and demonstrates good applicability. In this approach, the raw record is decomposed into a pulse signal containing permanent displacement and a nonpulse signal. The nonpulse signal is high-pass filtered to obtain the corrected nonpulse signal, and then the true ground motion is obtained by combining the pulse signal with the corrected nonpulse signal. The effectiveness of the proposed method is evaluated across five aspects using the 1999 Chi-Chi earthquake records: time histories, baseline offsets, response spectra, peak ground velocities, and peak ground displacements. Furthermore, the method is applied to 36 station records (108 components) of the 2023 Türkiye earthquake. The analysis results indicate that the corrected displacement time histories exhibit sustained flatness in their tails and demonstrate a closer agreement with the Global Navigation Satellite System (GNSS) measurements than the previous methods. This method can also incorporate static GNSS offsets to accurately determine true ground motions with precise permanent displacements. The corrected results can be utilized for nonlinear seismic calculations and structural damage analysis of fault-crossing structures such as bridges and tunnels.

Study on the Residual Strength of Nonlinear Fatigue-Damaged Pipeline Structures

The heat alternation and bending during the service process of the pipeline structure are the key issues affecting its residual strength. The nonuniform plastic deformation of its cross-section causes nonlinear damage to the structure, which makes it difficult to calculate the residual strength of the overall structure. This study proposed a novel variable-strength material damage model with damage accumulation, which achieved the coupling analysis of structural damage and material fatigue residual strength, making the structural strength of nonlinear damage cross-section computable. Based on this, a theoretical ultimate load model for nonlinear damage cross-section and a finite element analysis model for dynamic material strength with damage accumulation were established. The analysis was conducted on the repeated banding damage to coiled tubing. The results showed that the residual yield strength of nonlinear damaged coiled tubing showed a trend of first rapid decrease and then slow decrease with damage accumulation, and the tensile displacement showed an increasing trend with damage accumulation. The ultimate internal pressure strength of nonlinear damaged structures showed a similar downward trend to the yield strength. The nonlinear damage coupling analysis model proposed in this study has significant practical engineering application value.

Coupling four-parameters bond-based peridynamic and finite elements for damage analysis of composite structures

The difficulty in inferring the failure region is the main obstacle for applying coupling algorithms for progressive damage analysis of composite structures. This paper presents a new finite element and peridynamic (PD) coupling framework, in which an adaptive transformation technique is implemented for failure analysis of laminated structures. Since the mechanical properties of a multi-layer laminate can be characterized by single-layer finite elements, this coupling model (CM) exhibits great potential in balancing numerical accuracy and computational efficiency. During the damage evolution process, the single-layer finite element is adaptively transformated into multi-layer PD material points according to the transformation criterion as the load increases, and then the damage begins to nucleate and evolve in the PD subregions. Compared with other coupling models, the PD subregions adaptively appear in the potential failure sites, and its area is much smaller than other finite element subregions. Thus, the theoretical advantages of coupling algorithms in modeling multi-layer structures can be fully utilized, and the computational efficiency of numerical models will be greatly improved. The accuracy of the developed coupling model is demonstrated by the stretching example of composite laminates, and the damage examples of laminates with a cutout further demonstrates the strong capability of the proposed coupling model in capturing the failure characteristics.

A three-dimensional numerical simulation method for seismic nonlinear response of underground structure in liquefiable site and analysis of structural damage

Considering the effect of dynamic interaction between liquefiable soil and underground structure, simulating the nonlinear seismic response of underground structures through simple, convenient, and reliable 3D numerical model is still a great challenge at present. A three-dimensional numerical simulation method for dynamic response of underground structure in liquefiable site is proposed based on the centrifuge shaking table test designed for a subway station buried in liquefiable interlayer site carried out in the previous period. The numerical model takes into account the characteristics of sand prone to large deformation after liquefaction and the nonlinear characteristics of the contact between saturated soil and structure. The typical numerical calculation results are compared with the experimental results to verify the correctness of the numerical model, and the extended analysis of the structural damage is carried out, which visually shows the damage distribution of structure under different functional states after earthquake. The analysis of structural damage shows that the junction position of middle column and longitudinal beam is more prone to tensile damage under the horizontal earthquake action; while after considering the horizontal-vertical seismic effect, the middle column will produce additional compressive damage due to the vertical inertia force, and the end of middle column should be paid attention to in seismic design.

Theoretical aspects and applications of goal‐oriented reanalysis methods

AbstractIn this contribution, a method for goal‐oriented reanalysis is presented. The process allows predicting the change in a quantity of interest due to structural modifications (design changes), for example, the shape, the topology, material properties, and so forth. The approach is based on a goal‐oriented method using primal and dual problems. Furthermore, the procedure is easy to implement in existing finite element programs because no derivatives with respect to the design variables are necessary. The proposed method can be used in classical applications with successive design steps, such as structural optimization, reliability, or structural damage analysis. The repeated structural analysis and calculating quantities of interest involve significant computational effort. Goal‐oriented reanalysis methods can reduce the overall computational cost in the numerical simulation.

The influence of load correlation on vibration fatigue damage of symmetrical notched cantilever beam structures

AbstractThis paper aims to develop an innovative multiaxial fatigue criterion based on the stress invariant, in order to perform the fatigue damage analysis of engineering structures subjected to random vibrations. First, the change rule of structural vibration fatigue lifetime under different load correlation conditions is systemically studied by experiments. Then, the finite element analysis of such a structure, including the modal analysis and the spectral analysis, is implemented in order to compute the response stress power spectral density (PSD) functions at the critical fatigue‐prone location under coupled random acceleration base excitations. Finally, the influence rule of load correlation on the vibration fatigue damage of such a symmetrical structure is theoretically illustrated through formula derivation. Moreover, combined with the critical distance theory point method, the proposed time/frequency‐domain multiaxial fatigue criterion is applied for vibration fatigue lifetime evaluation of the structure. The lifetime prediction accuracy of the proposed multiaxial fatigue criterion is verified by comparing with the vibration fatigue test results.

The analysis of crashworthiness and dissipation mechanism of novel floating composite honeycomb structure against ship-OWT collision

High-energy ship collisions can cause catastrophic damage to offshore wind turbines (OWTs). This paper proposes a novel floating composite honeycomb anti-collision structure to reduce damage caused by ship-OWT high-energy collisions. The typical collision scenarios are conducted to investigate the damage analysis of anti-collision structures and the dynamic response of OWT with and without anti-collision structures via ABAQUS/Explicit. Regarding the configuration of the composite honeycomb anti-collision structure, the elastic-plastic theory of sandwich beams is proposed and an elastic-plastic analysis on the sandwich wall honeycomb core structure is performed to investigate its dissipation mechanism and obtain homogeneous material parameters of the cells. The homogenization parameters are incorporated into the ship-OWT anti-collision analysis to evaluate their applicability. The collision simulation results demonstrate that the proposed anti-collision structure is capable of effectively absorbing 80% of the initial kinetic energy and significantly reducing the dynamic response of the structure. In elastic-plastic analysis, the proposed elastic-plastic theory of sandwich beams effectively addresses the elastic-plastic behavior of honeycomb with sandwich walls, yielding results consistent with the stress-strain curve obtained from finite element analysis (FEA). In the coupled analysis, the obtained parameters of the homogenized honeycomb validate its effectiveness and enhance computational efficiency. Valuable results are given for the engineering design.

Damage analysis of Nomex honeycomb sandwich structures using image processing and artificial intelligence approaches

AbstractIn this study, a method was developed to detect impact damage and determine the damage propagation in increasing and repetitive impacts. The effect of nanographene additives on the propagation of delamination damage in the top face layer of a sandwich structure was investigated using the developed method. In addition, the effects of nanographene on visible (VID) or barely visible damage (BVID) formation were investigated, and the stiffness of the sandwich structures was evaluated. An ultrasonic C‐scan nondestructive testing was used to visualize the damage, and the numerical values of the damaged areas of the sandwich structures at different energy levels were determined using an image processing method. The obtained values were used in artificial neural network (ANN) training to estimate the impact energy at which the structural integrity of the sandwich structures was disrupted. It was observed that the nanographene additive was effective in maintaining rigidity of the sandwich structures and therefore, slowed the delamination damage progression in increasing and repeated impacts. The damage areas of the neat sandwich structures (NSS) and graphene nanoplatelets doped sandwich structures (GSS) structures at the first impact 5j energy level was 1004 and 811 mm2, respectively. At the first impact, 20% less damage occurred in the GNP‐doped sandwich structures. The increasing and repetitive last impact energies at the end of the neural network training were 5j + 35j in NSS and 5j + 50j in GSS. The method allows for a detailed examination of the damage progression of sandwich structures under increasing and repeated impact loads.Highlights Low‐velocity impact tests of Nomex honeycomb sandwich structures were performed. Damage formation and propagation in sandwich structures were investigated. The non‐destructive test C‐scan method was used to determine BVID. The damaged areas were determined using an image processing method. The damage areas were estimated using artificial neural networks.

A new generation method of tunnel progressive defect status random field (TPDSRF) for subway tunnel structure

Subway tunnels are exposed to the risk of multiple hazard attacks such as earthquakes, fires, and explosions during operation, which can cause significant damage to their structure. The presence of progressive defects can exacerbate this damage, but existing hazard design methods do not consider their effects, leading to inaccurate damage assessments. To fill this gap, this study proposes a method to characterize the state of progressive defects in the design stage that may appear in a shield tunnel during a tunnel's operational phase. Firstly, based on the progressive defect situation of the operating tunnels, it was determined that the s status of the defects can be described by stochastic and correlation characteristics. To describe these characteristics, the Tunnel Progressive Defect Status Random Field (TPDSRF) is defined. The study then derives the parameters and range of five progressive defects that describe TPDSRF, using a combination of engineering measurement data and literature research. Finally, the study describes the entire generation process in detail and simulates a TPDSRF for a 1000 rings subway tunnel. Results show consistency with preset values and tunnel progressive defect patterns, demonstrating the feasibility of the proposed method. The results of the study can provide a improving initial state of the structure for hazard analysis, which is important and essential for the analysis of structural hazard damage under the consideration of progressive defects.

Analysis of Undrained Shear Characteristics and Structural Damage of Granite Residual Soil

Three-dimensional consolidation testing, scanning electron microscopy, and undrained triaxial testing of granite residual soil (GRS) in Shenzhen, China, were conducted. The effect of the structural strength of GRS was quantitatively analyzed using the method of comprehensive structure potential parameter description. The failure strength ratio of the soil decreases with increasing confining pressure, and it is approximately 1 when the confining pressure is higher than the yield stress (σs). The undrained shear strength (Su) of the undisturbed soil varies in stages with confining pressure σ3. The relationship between Su and σ3 for the reconstituted soil is approximated as a straight line through the origin. The soil's comprehensive structure potential parameters (the structural contribution rates of the tangential shear modulus, mE, and the deviatoric stress, md) decrease linearly with increasing σ3. The mE and md sample values are similar under the same confining pressure. It is reasonable to use structure potential parameters to quantitatively evaluate the structure contribution rate of GRS. The microstructure is constantly adjusted, and the soil microstructure form for different confining pressures strongly correlates with its shear characteristics.

Experimental Investigations of the Seismic Response of a Large Underground Structure at a Soft Loess Site

Based on an underground structure located at a soft loess site in Xi’an as the engineering background, this paper investigated a seismic response and damage model of subway stations at a soft loess site using a large-scale shaking table test, considering the different characteristics of ground motions. The quantitative analysis of the acceleration response and the seismic subsidence of the soft loess site were subjected to different earthquake excitations; based on the experimental results and the corresponding analysis, the development and distribution of seismic structural damage were studied, and the damage mechanism of underground structures in a soft loess area under a strong earthquake was explored. The results indicate that the peak accelerations of the site soil first remained unchanged then increased significantly along the soil height, and the amplification effect of the acceleration response was the most significant at the soil surface. The soft loess soil underwent significant subsidence, and the underground structure was raised compared to both sides of the cover soil; the collapsibility of the soft loess soil was sensitive to strong earthquakes with vertical components. The underground structures in soft loess suffered heavy damage, which rapidly entered the elastic–plastic stage. The composite effect of the collapsibility and vertical seismic excitation impaired the load-carrying capacity of the middle columns, and the strong horizontal seismic excitation enlarged the lateral force and accelerated structural damage development; the underground structure reached failure when plastic damage expended most of the middle columns and structural joints. These results are significant for the seismic design of underground structures in adverse soil conditions.

Research Review on Earthquake Resilient Structures

As researchers summarized their experiences with earthquake disasters, they found that the traditional seismic design concept of only regarding preventing collapse of structures under earthquake loads as the primary seismic defense objective for structures, has deficiencies in post-earthquake use and repair. Therefore, the concept of resilient structure design was proposed, which enables structures to quickly repair to pre-earthquake functional levels after earthquakes. Currently, the concept of resilience is gradually becoming the core theory of seismic design. This paper reviews the shortcomings of traditional seismic design concepts, introduces the two core objectives of resilient structure design, namely "reducing post-earthquake residual deformation" and "reducing post-earthquake structural damage and damage concentration." Resilient structures are mainly classified into rocking structures, structures with self-centering braced, and structures with replaceable member according to their implementation methods. The principles and research progress of these three structures are summarized. The deficiencies of existing building structural seismic performance are analyzed, and the reinforcement technology and practical engineering extension applications of the resilience concept in the reinforcement of existing structures are introduced. The prospects of the resilience concept in interdisciplinary research, post-disaster structural damage analysis, practical engineering applications, and other aspects are proposed.

Microstructural Changes of High Strength Concrete during Low Cycle Compression Fatigue Test after Exposure to High Temperature

Using ultrasonic detection, microhardness test, scanning electron microscope test, mercury intrusion method and X-ray diffraction, the parameters of sonic time, microhardness, pore size distribution, cumulative pumping of high strength concrete under low cycle compression loading are tested after exposure to 200 °C, 400 °C and 600 °C. Experimental study showed that with the increasing loading times, the rangeability of sonic time, the microhardness, and total pore volume shows an overall trend of fast-slow-fast. Furthermore, the sonic time and microhardness are linearly related to the longitudinal fatigue strain. The research results provided references for nondestructive testing, fatigue damage analysis and structural evaluation of concrete structures subjected to fire or other high temperature processes.