Response Analysis Of Structures Research Articles

Simplification of large-scale solid element model for seismic structural response analysis of buildings  

Simplification of large-scale solid element model for seismic structural response analysis of buildings  

Dynamic response analysis of three-dimensional U-shaped negative Poisson's ratio periodic structures

Dynamic response analysis of three-dimensional U-shaped negative Poisson's ratio periodic structures

Rasch Analysis of the Dermatology Life Quality Index

Previous results of the Dermatology-Life-Quality-Index (DLQI) validation in Colombia based on the classical test theory (CTT) perspective have showed the need to delve into its measurement properties. Therefore, we aimed to assess the structural validity, internal consistency and item response analysis of the DLQI through the item response theory (IRT) or the Rasch model. We assessed the dimensionality of the DLQI, determined its difficulty, discrimination and differential functioning and went on to evaluate its internal consistency and discriminative validity among patients with inflammatory and non-inflammatory skin disease. We recruited Colombian patients with different skin diseases. Data of 865 patients (mean age, 49.3 years; 61% females) were included. DLQI-scores ranged from 0 up to 30. Internal consistency for dichotomous item #7 showed a McDonald's Omega coefficient of 0.85 (95%CI, 0.84-0.87) and a Cronbach's α coefficient of 0.86 (95%CI, 0.84-0.88). For ordinal item #7, the McDonald's Omega coefficient was 0.87 (95%IC:0.85-0.89) and Cronbach's α coefficient, 0.84 (95%CI, 0.82-0.87). Horn's parallel analysis revealed the presence of DLQI unidimensionality with a 1-factor solution. Only item #1 fitted the PCM model. The remaining items, including item #9, did not show adequate fit due to overlapping responses and order changes. The validity of DLQI-COL based on Rasch analysis proved not to be a suitable instrument to evaluate QoL in our dermatologic population. A refined version of the scale with an adequate cross-cultural adaptation and validation process is needed to obtain an appropriate and reliable version of the instrument for QOL measuring in Colombian patients with skin diseases.

Numerical Simulation of the Hydrodynamic Behavior of an Offshore Platform Supported by a Jacket Structure in Waves

The offshore jacket structure has the advantages of suitable stiffness, convenient construction, anti-collision, and strong fatigue resistance, and it is the main structural form of offshore converter station. By constructing a numerical wave tank for the hydrodynamic response analysis of the offshore jacket structure, the wave field distribution around and the wave slamming load on the offshore jacket structure for the converter station under the action of waves are analyzed based on the Star CCM+ software 2206. In addition, the effects of wave height and wave period on its hydrodynamic loads are discussed. The results indicated that: (1) A thin jet layer can be formed on the wave-facing side of the square box when the waves attack the box, and the height of the jet is not the maximum when the horizontal load generated by the jet at the front of the box reaches the maximum value. (2) The pressure distribution on the wave-facing side of the square box for the converter station is relatively discrete, with the pressure in the middle part being slightly larger than that on both sides. At the bottom of the box, the pressure in the middle and back part is significantly larger than that in the front part. (3) When the waves attack the box for the converter station, it caused significant energy dissipation, and the horizontal load on the offshore jacket is less than that when no wave slamming occurs.

Dynamic response analysis and optimization of orbital support structure

In order to further enhance the stability of the orbital transportation, the modal characteristics of the orbital support structure were simulated and analyzed. The multi-objective optimization method was applied to design the structure for lightweighting while increasing the first-order natural frequency and reducing the stress peak. Using ANSYS Workbench, the parametric finite element model was established, the length of the intermediate support rod, and the lateral length of the rib were regarded as the parameterized dimensions. Through dynamic characteristic analysis, the natural frequencies, modal shapes, and harmonic response characteristics were obtained. Parametric samples were obtained by using Latin square method, and the approximate model was fitted by polynomial function. Multi-Objective Genetic Algorithm and Sequential Quadratic Programming were applied for optimization calculation. The results indicate that the structurally lightened design can attain higher strength and stiffness.

Seismic vulnerability of steel tubular structures based on local Buckling driving variables

Performance-Based Earthquake Engineering (PBEE) is computationally demanding, due to the multiple high-fidelity non-linear dynamic structural response analyses required to compute fragility curves. In this manuscript we propose an efficient procedure to obtain fragility curves of complex tubular structures prone to fail due to local buckling using a model based on the Lumped Damage Mechanics. A state variable characterizing local buckling is employed as engineering demand parameter in PBEE. This state variable is a scalar, derived from lumped damage mechanics and taking values between 0 and 1, which characterizes the degree of local buckling (LB). A procedure to identify and define global collapse mechanisms using the local buckling state variable at the nodes is proposed, which serves as the EDP for computing the structure's fragility curves. To evaluate the seismic vulnerability, incremental dynamic analyses are conducted. The main results demonstrate efficiency of the mechanical model in a PBEE framework, and that the internal variables indicating local buckling can be considered objective indicators of collapse for Tubular complex steel frames. Results show how to identify the global failure mechanisms that are more likely to appear for each frame.

The strong ground motion and structural response analysis of 06 February 2023 Pazarcık and Elbistan earthquakes (Mw 7.7 and 7.6): a Case study for Malatya-Türkiye, Eastern Anatolia

The strong ground motion and structural response analysis of 06 February 2023 Pazarcık and Elbistan earthquakes (Mw 7.7 and 7.6): a Case study for Malatya-Türkiye, Eastern Anatolia

Structural response analysis of tungsten-steel composite warheads with different geometries under three typical transverse loads based on the rigid-perfectly plasticity

Abstract Heavy metals such as tungsten were demonstrated helpful in increasing warheads’ penetrating ability, and used in practical warhead designs. Until recently, a relatively practical analytical method based on the rigid-perfectly plastic theory was proposed. This paper used this method to analyse the structural response of different heavy metal-involved designs under different transverse loads. The results show that the yield functions of warheads with tungsten in different geometries show a two-peak structure, and the critical section does not essentially appear at the first peak, but also might be at the second one, and even jump from one to the other. Besides, bonding strength plays a positive role in improving the impact resistance of the warhead. It should be noted that the tungsten part might do harm to the bearing capacity of the warhead, and attention should be paid to balance the penetrating and bearing ability. More practically, careful design of the inertia distribution along the axis might counteract the negative effect of the tungsten part on the structural integrity.

Engineering method for quantifying the coupling effect of transmission tower-line system under strong winds

For transmission tower-line (TL) systems, the coupling effect between line cables and towers under strong winds is significant. This paper presents a method to quantify the coupling effect. Assuming that effective separation of line cables and towers is attainable, this work transforms the coupling effect into the transferred load from the line cable to the target tower, the coupling participation mass of the line cable, and the additional damping. The effective separation conditions are defined through an optimization method minimizing the residual errors of the wind-induced response and dynamic characteristics between the separated bodies and the TL system. A typical TL system is considered and analyzed for its structural dynamic characteristics and wind-induced response. Particularly, the quantities associated with the coupling effect of the TL system are estimated. It reveals that the transferred dynamic load component parallel to the line cable which is overlooked in current codes is significant and highly sensitive to the separation boundary conditions of line cables. Furthermore, the coupling participation mass of the conductor is more prominent than that of the ground wire. The proposed method is feasible for quantifying the TL coupling effect and incorporating it into the wind-induced response analysis of transmission line structures.

Deep learning-based ground motion inversion through recursive structural acceleration response using DRA-LSTM Net

Known ground motion time history is crucial for the precise numerical analysis of structural response and evaluation of its safety. This study introduces the Deep Recursive Attentive Long Short-Term Memory Network (DRA-LSTM Net), a framework designed for the inversion of ground motion (GM) from recorded structural response (SR) during an earthquake. By integrating an attention mechanism in network along with a strategic recursive approach for dataset management, the DRA-LSTM Net achieves high precision in GM inversion. The method incorporates a novel pre-processed matrix format to capture unique recursive behaviour patterns in GM data, enhancing the model’s training, validation efficiency, and prediction accuracy on unseen test datasets. Case studies on single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) structures highlight the method’s potential for real-time and high-precision GM inversion. Additionally, transfer learning was implemented to fine-tune the pre-trained model with real-world sensor data and structural responses from different floors, demonstrating the model’s adaptability and ability to retain high prediction accuracy across diverse datasets. This approach is particularly useful for regions with limited seismic instrumentation but equipped with structural response sensors.

Rasch Analysis Of The Dermatology Life Quality Index

Background and aims: Previous results of the Dermatology-Life-Quality-Index (DLQI) validation in Colombia based on the classical test theory (CTT) perspective have showed the need to delve into its measurement properties. Therefore, we aimed to assess the structural validity, internal consistency and item response analysis of the DLQI through the item response theory (IRT) or the Rasch model.Material and methods: We assessed the dimensionality of the DLQI, determined its difficulty, discrimination and differential functioning and went on to evaluate its internal consistency and discriminative validity among patients with inflammatory and non-inflammatory skin disease. We recruited Colombian patients with different skin diseases.Results: Data of 865 patients (mean age, 49.3 years; 61% females) were included. DLQI-scores ranged from 0 up to 30. Internal consistency for dichotomous item #7 showed a McDonald’s Omega coefficient of 0.85 (95%CI, 0.84-0.87) and a Cronbach's α coefficient of 0.86 (95%CI, 0.84-0.88). For ordinal item #7, the McDonald's Omega coefficient was 0.87 (95%IC:0.85-0.89) and Cronbach's α coefficient, 0.84 (95%CI, 0.82-0.87). Horn’s parallel analysis revealed the presence of DLQI unidimensionality with a 1-factor solution. Only item #1 fitted the PCM model. The remaining items, including item #9, did not show adequate fit due to overlapping responses and order changes.Conclusions: The validity of DLQI-COL based on Rasch analysis proved not to be a suitable instrument to evaluate QoL in our dermatologic population. A refined version of the scale with an adequate cross-cultural adaptation and validation process is needed to obtain an appropriate and reliable version of the instrument for QOL measuring in Colombian patients with skin diseases.

Improved tropical cyclone boundary layer model and its application in floating offshore wind turbine structural response analysis

The accurate simulation of tropical cyclone (TC) wind fields is essential for analyzing structural responses, given the potential severe damage to infrastructure caused by TCs. An improved TC boundary layer mean wind field model is proposed, building upon the Kepert model, by introducing a two-dimensional pressure field that varies with height and radius, a surface turbulent diffusivity influenced by wind speed at the lower boundary, and a surface roughness length affected by waves and spray. The accuracy of the improved model is validated through comparisons with TC observational data. Comparative analysis indicates that the Kepert model overestimates the tangential wind speed component. The two-dimensional pressure field employed in the improved model more accurately simulates the central pressure difference within the TC boundary layer. Furthermore, the incorporation of a surface turbulent diffusivity and sea surface roughness length that better reflects physical phenomena further enhances the accuracy of the improved wind field model. The structural responses of a floating offshore wind turbine (FOWT) situated in the TC eyewall region under emergency shutdown conditions are computed using both wind field models separately. The results indicate that blade tip displacement, tower top displacement, platform translation, and rotation responses (pitch and yaw) are overestimated by the Kepert model. In conclusion, the improved model accurately represents the TC structure, offering precise wind field data for assessing FOWT structural responses in TC conditions.

Pyrolysis modelling of insulation material in coupled fire-structure simulations

This paper presents a modelling approach to predict the thermodynamical and thermomechanical behaviour of structures with a layer of insulation material under fire, which takes into account the pyrolysis of the insulation and its effects on the structure. First, an existing 1D pyrolysis model is implemented and verified by theoretical and validated by experimental results. Then the model’s 1D setup is integrated into 3D Heat Transfer (HT) analyses of structures. The obtained thermodynamical results, i.e. temperatures as a function of time and the pyrolysis process, are transferred to a thermomechanical Structural Response (SR) analysis. Mechanical results are then obtained via temperature and pyrolysis-dependent material properties. The resulting HT and SR analyses are demonstrated in fire-structure simulations of facades made of sandwich panels, including their supporting frames with steel sections, and bolt and screw connections, modelled by non-linear spring elements. It is shown that in a short time window of 100 s, pyrolysis is limited to certain zones of the panel and for limited depths. Nevertheless, due to the endothermic process, it reduces expansion and bending of the panels, and consequently results in smaller displacements, and delayed failure of the connections. For longer periods, with connection failures neglected, significant pyrolysis takes place, which influences the temperature distribution in the complete interior of the sandwich panel. However, this has only a marginal effect on the structural behaviour. In conclusion, pyrolysis effects are relevant, can be modelled, and may somewhat reduce fire risks in structures. Future research can combine pyrolysis with advanced modelling of bolt and screw connections, using a two-scale method. As such, all relevant details of structures can be modelled and investigated for different fire scenarios, including fire-structure effects, all still to be validated by experiments.

Fragility analysis of tubular structures based on local-buckling driving variables

Performance-Based Earthquake Engineering (PBEE) is computationally demanding, due to the multiple high-fidelity nonlinear dynamic structural response analyses required to compute fragility curves. Local buckling of tubular steel structures is not properly characterized by typical Engineering Demand Parameters (EDPs) such as story drifts or plastic rotation angles. Targeting the two issues above, in this manuscript we propose using state variables based on Lumped Damage Mechanics (LDM) to characterize Local Buckling (LB) in PBEE. Hence, we propose an efficient and innovative procedure for the fragility analysis of complex tubular structures prone to fail due to local buckling. Moreover, local buckling produces a loss of stiffness, with loads transferred to intact or to less-damaged elements. Eventually, the structure forms a global collapse mechanism. Herein, we show how to identify the most likely global collapse mechanism in non-symmetrical tubular structures subjected to random seismic loading. This involves evaluating damage indices in different elements and their correlation, as well as identifying the combination of LB failures that are more likely to form a global collapse mechanism. Fragility curves characterizing the onset of LB at individual elements, and the most likely global collapse mechanism, are constructed. A simple frame structure is addressed, where the accuracy of the LB-LDM model is checked against experimental results. Another case study involving a non-symmetric tubular wharf illustrates the search for the most likely global collapse mechanism, and the derivation of its fragility function.

Smeared fixed crack model for quasi-static and dynamic biaxial flexural response analysis of aluminosilicate glass plates

Glass materials are extensively used in load-bearing structures and impact-resistant components because of their distinctive physical and chemical properties. Accurate predictions and assessment of the mechanical responses of glass structures are crucial for structural design and reliability analysis. In this study, quasi-static and dynamic ball-on-ring (BOR) biaxial flexural tests are conducted on aluminosilicate glass. The smeared fixed crack model is calibrated for deformation and failure analyses. First, the model parameters are calibrated carefully, particularly for different failure criteria. Both the deformation field and fracture modes agree well with the experimental observations during the quasi-static tests. For the low-velocity impact biaxial flexural loading condition, three different numerical techniques, namely the initial scaling tensile strength criterion, non-local approach with energy criterion, and rate-dependent failure stress criterion, are implemented in the numerical models for dynamic failure analysis. Finally, the proposed smeared fixed crack model is compared with the widely used Johnson Holmquist Ⅱ (JH-2) model and demonstrates advantages for low-velocity impact response analysis of glass structures.

Dynamic response and vibration suitability analysis of the large-span double-connected structure under coupled wind and pedestrian loads

Modern buildings increasingly utilize lightweight, high-strength materials and feature high-rise, large-span structural designs. These structures often exhibit low natural frequencies and are susceptible to resonance from low-frequency dynamic loads such as wind and pedestrian loads. This paper focuses on a large-span double-connected structure and analyzes its dynamic response under the combined effects of wind and pedestrian loads. First, a finite element model of the structure was created using ANSYS, and model validity verification and modal analysis were performed. Second, a Fourier-based pedestrian model was used to simulate pedestrian loads and generate time-range data. The pulsating wind speed was generated from the Davenport spectrum using the harmonic superposition method. Wind load time-range data were calculated for different heights using Bernoulli’s theorem. Finally, the solution yields information about the dynamic response of the structure. The study revealed maximum vertical comfort ratings in the connecting corridor were achieved when crowd density did not exceed 0.3 persons/m2. The connecting corridor’s most unfavorable horizontal comfort level was evaluated as a medium, except for the 0-degree wind angle condition. This paper provides experience in studying the dynamic response and vibration suitability assessment of the large-span double-connected structure under wind and pedestrian loads.

Quantitative Property of MF-Discrepancy and Efficient Point-Selection Strategy for the Nonlinear Stochastic Response Analysis of Structures with Random Parameters

The response analysis of high-dimensional and strongly nonlinear systems with random parameters remains a significant challenge in stochastic computational mechanics. To address this challenge, some methods based on the high-efficacy point sets have been developed, in which efficient global-point-set methods represented by low-discrepancy are of paramount importance in generating representative point sets. Several discrepancies including the extended F-discrepancy (EF-discrepancy) and the generalized F-discrepancy (GF-discrepancy) have been introduced to assess the uniformity and the efficacy of a representative point set. In such context, a maximal marginal EF-discrepancy (MF-discrepancy), which is an extended form of the GF-discrepancy, is proposed in this paper and then the properties of the MF-discrepancy are studied in detail. The probability distribution of the MF-discrepancy is derived, including a rigorous proof for random point sets and a model based on an assumption for some generic point sets. A generalized Koksma-Hlawka inequality is established accordingly to govern the worst error estimate. The lowest bound of the MF-discrepancy is given, and two intuitive quantitative indices are proposed to measure the goodness of the MF-discrepancy. Based on the lowest bound, an enhanced point-selection strategy with a unified theoretical framework for minimizing the MF-discrepancy is proposed. In this framework, locally minimizing the MF-discrepancy yields the two-step point-selection method, and a new point-selection strategy is proposed based on the global minimization of the MF-discrepancy, which is verified to be efficient and robust, especially in high-dimensional cases. Several numerical examples, including a 2-story shear frame, a 10-story shear frame, and a 10-story reinforced concrete frame structure modeled by the finite element method, are studied, verifying the efficiency and the robustness of the proposed point-selection strategy.

Structural Response Analysis and Comfort Evaluation of Residential Buildings: A Combined Wind Tunnel and FEM Approach

With global urbanization accelerating, high-rise buildings have become a common feature in the urban landscape, especially in coastal cities, where they encounter unique wind-load challenges. This study aims to quantify the structural response and occupant comfort of a high-rise residential building under wind-induced accelerations by integrating wind tunnel testing with finite element analysis (FEA). The research focuses on critical response parameters, including displacement, acceleration, and stress, to evaluate the building’s performance. Wind tunnel tests provided detailed wind pressure distribution data across the building’s surface, while multi-degree-of-freedom and finite element models facilitated precise numerical simulations. The findings highlight a significant directional and temporal variability in wind-load responses, with the most pronounced effects observed at a wind-direction angle of 105° relative to the building’s front-facing axis (0°). The study confirms that the combined application of wind tunnel tests and FEA offers a comprehensive approach to understanding wind-induced responses, essential for the scientifically accurate and effective design of high-rise structures.

Review of Earthquake Resistance and Mitigation of Underground Structures

The rapid development of underground structural engineering in China has been accompanied by pressing issues in the research of earthquake resistance and mitigation. Typically, underground structures exhibit good seismic performance with relatively few disasters. However, once they are damaged by earthquakes, the consequences can be severe and difficult to repair. This paper first elaborates on the prototype observation, theoretical analysis, model testing, and numerical simulation involved in seismic response analysis of underground structures. It comprehensively analyzes the advantages, disadvantages, and applicability of different research methods. Finally, it summarizes the research achievements on technical measures to mitigate earthquake damage to underground structures in strong earthquake regions, both domestically and internationally.

An efficient method for evaluating the wind resistance performance of high-vertical standing seam metal cladding systems

Uplift wind-induced responses and failure criteria of high-vertical standing seam metal cladding systems (SSMCSs) are of paramount importance for evaluating their wind resistance performance. This paper proposes an efficient evaluation method that combines a highly efficient finite element (FE) model for structural response analysis with reasonable failure criteria, based on experimental and numerical investigation. The FE model incorporating the developed equivalent spring model is established with the calibrated stiffness from tensile tests and validated through the wind uplift resistance experiments conducted on large-scale prototype structures. The recorded structural responses from the experiments validate the feasibility of the FE model in simulating the geometric and material nonlinearities of the systems. To evaluate the wind resistance performance, the failure criteria are developed based on the observed pullout mechanisms and failure modes from the experiments. These criteria take the relative deformation of standing webs and the pullout resistance strength of seam connections as critical parameters, and the relationship between them is calibrated through a series of tensile tests using a self-designed fixture. Tensile test results show notable variability in the pullout resistance strength of seam connections, with a mean value decreasing as the relative rotational angle of the standing webs increases. According to the developed failure criteria, the ultimate uplift pressures evaluated from the FE analysis exhibit minimal positive deviations of 5.3 % and 7.3 % from the experimental results for different failure modes, respectively. This highlights the effectiveness of the proposed method in evaluating the wind resistance performance of high-vertical SSMCSs.