Structural Response Research Articles

ANALYSIS & DESIGN OF G+20 BUILDING ON A SLOPY GROUND BY USING STAAD PRO

This study focuses on the analysis and design of RCC multi-storeyed G+14 framed buildings with both regular and irregular plans, using STAAD Pro software. The objective is to model and analyze the buildings under seismic loads through equivalent static analysis. Key areas of study include the comparison of regular and irregular building configurations and the impact of shear walls on seismic performance. The research investigates the structural behavior, including displacement, stress distribution, and stability of buildings subjected to lateral seismic loads, with a focus on buildings with and without shear walls. The findings reveal significant differences in the structural responses between the two configurations, highlighting the importance of shear walls in improving seismic resistance. The study concludes that shear walls enhance the structural integrity and reduce lateral displacements, providing recommendations for designing safer buildings in seismic zones. The research aims to offer valuable insights for effective design strategies to ensure safety and minimize seismic damage in multi-storeyed RCC buildings. Keywords: RCC, multi-storeyed, G+14 framed buildings, regular and irregular plans, STAAD Pro, seismic loads, equivalent static analysis, shear walls, structural behavior, displacement, stress distribution, stability, seismic resistance, seismic zones, structural integrity, effective design strategies.

Vibrational Analysis of Building Structures with Irregularities

This paper presents a mathematical model for predicting vibrations in lightweight, timber-based floor/ceiling structures, enhanced to account for irregularities in joist shape and stiffness, as well as floor stiffness. Building on a prior model that assumed precise geometry and homogeneous material properties, the study now incorporates real timber measurements via the power spectral density of irregularities to incorporate their impact on the system’s vibrational response, including mid-frequency vibrations. Existing results underscore the critical role of component connections in shaping vibration behavior, while the present paper gives new principles for building a model to assess how uncertainties in these connections or material properties affect the overall structural response. This new model maintains the property of efficient computation so that irregularities in the components may be included in the design stage to improve the mid-frequency performance of lightweight, timber-framed structures.

A multi-fidelity approach for the evaluation of extreme wave loads using nonlinear response-conditioned waves

In the present study, a multi-fidelity methodology based on response-conditioned waves (RCW) is demonstrated for the probabilistic assessment of wave-induced loads and responses of offshore structures. The methodology consists of two steps: (i) the RCW are determined using a surrogate response model and (ii) they are reproduced in an experimental or CFD-based numerical wave tank (NWT) to obtain the fully nonlinear response, as a high-fidelity evaluation. The main novelty of the proposed response-conditioning technique is that it uses a fully nonlinear wave solver that calculates the wave propagation inside an NWT. In this work, the extreme Vertical Bending Moment (VBM) of a zero-speed containership is investigated. It is found that the proposed approach provides nonlinear wave sequences that can be explicitly and exactly reproduced experimentally, up to very extreme sea states (Hs=17 m, Tp=15.5 s). Moreover, through comparison of the obtained results with an experimental Monte Carlo approach, it is shown that the overall framework can predict the short-term distribution of the VBM accurately and efficiently. Finally, given that model tests are costly and not widely accessible, the implementation of the high-fidelity response evaluation within a CFD-based NWT is also demonstrated and validated against the available experimental results.

Emergent local negative electrostriction induced by oxygen vacancy in BaHfO3: Defect engineering

Realization of ultrasmall scale electromechanical materials has been promising for advanced functional devices. Recently, single-atom devices have been proposed as the ultimate miniaturization of functional devices beyond the nanoscale; however, achieving an atomic-scale local electromechanical response is still challenging due to physical size limitation of electromechanical properties as well as technical difficulties in fabricating the functional materials in a single atom precision. Here, we demonstrate a non-trivial negative electromechanical response at an oxygen vacancy in paraelectric BaHfO3 using first-principles finite electric field calculations. We find an electrostrictive response at the vacancy site in the same order of magnitude in well-known oxide materials. Surprisingly, we also discover an unusual “negative” sign of electrostriction in the oxygen vacancy. The detailed electronic structure analysis demonstrates that a unique electric field response of a localized defect electronic structure is the origin of this negative electrostriction of vacancy. The present results provide an important implication for the design of ultra-small electromechanical functions at an atomic scale.

CBCT Analysis of the Hyoid and Pharyngeal Airway Changes in Class III Patients With Orthognathic Surgery.

This study was designed to investigate the response of the respiratory structures to orthognathic surgery in patients with Class III malocclusion, with a specific emphasis on the vertical placement of the hyoid bone. The correlations of these changes were also analysed, followed by further subgroup analyses based on preoperative conditions. Dolphin software was used to obtain cephalometric landmarks, airway and hyoid bone measurements from pre- and postoperative CBCT scans of 31 patients. Statistical analyses included paired t-tests and Pearson's correlation analysis. Stomatological mandibular values and the nasopharynx height showed significant changes. Pearson's correlation identified significant correlations between changes in B and H horizontal coordinates (p < 0.05), as well as between changes in H longitudinal coordinates and specific airway dynamics (p < 0.05). Patients with a lower preoperative hyoid position experienced a more pronounced decrease in hypopharyngeal airway volume after surgery compared to those with a higher preoperative hyoid position, as evidenced by the significant mean differences and p values (p < 0.01). Class III patients experienced airway constriction following orthognathic surgery, particularly those with a lower preoperative hyoid bone position, who showed a more significant decrease in hypopharyngeal airway volume postsurgery compared to those with a higher preoperative hyoid position. These findings underscored the importance of individualised surgical planning and highlighted the need for further research with dynamic assessments to optimise respiratory outcomes.

Residual displacement ground-motion model

Residual displacement (RD), indicative of permanent post-earthquake deformation resulting from nonlinear structural response, plays an important role in assessing structural integrity and seismic safety. This study introduces a ground-motion model (GMM) for predicting RDs in inelastic single-degree-of-freedom systems, utilizing a large database of recorded ground motions. The RD GMM adopts key input parameters including 5%-damped elastic pseudo-spectral acceleration (PSA) over periods from 0.01 to 4.0 s, yield strength coefficient (Cy), earthquake magnitude (M), and closest distance to the fault rupture plane (Rrup). Levels of inelasticity are accounted for by employing the yield strength reduction factor, denoted as (PSA/g)/Cy. The results indicate that while M and Rrup significantly affect RDs, site class and significant duration have relatively less influence. RD GMM coefficients and unconditional standard deviations of the model are provided for specific Cy values across a period range of 0.01–4.0 s. The analyses indicate relatively large standard deviations in the GMM due to inherent variability in residual displacement, highlighting the importance of understanding and accounting for this variability in seismic design and performance assessment. Validation against a multi-degree-of-freedom bridge residual drifts demonstrates the effectiveness of the model in predicting the distribution of residual drifts.

Investigating the influence of plate geometry and detonation variations on structural responses under explosion loading: A nonlinear finite-element analysis with sensitivity analysis

Abstract This study presents the results of a numerical analysis of the response of Domex 700 and Dormex 1100 steel plates with varying geometries, combined with several different parameters such as a thickness of up to 6 mm and a trinitrotoluene (TNT) mass. Using ABAQUS software, finite-element analysis was run to examine the structural response ability of the steel plates to explosions. In terms of deformation and energy dissipation, the results showed a large differentiation. A sensitivity analysis was used to examine each simulation result in terms of the structural response performance to explosions and identify the variables that had the greatest impact on variations in the thickness, material, geometry, and TNT mass. The best numerical simulation results were found using the multi-attribute decision-making (MADM) approach. Annotations are utilized to assist in identifying the various modifications made during testing. Annotations LXXI to LVIII achieved the lowest value of 6.176 × 10−09, signifying the best results according to calculations made using the MADM approach. This is evidenced by the structural events, demonstrating that the deformation, von Mises stress, and energy dissipation in the circular plate structure were not significantly impacted by the explosion. The variables that most significantly affect variations in deformation, von Mises stress, and dissipated energy – variables that significantly impact the structural response to explosions – are identified through the sensitivity analysis approach. The results of this research can be used to optimize the structural response performance of circular plates.

An Investigation of Structural Integrity and Dynamic Response of CSB in Case of Slanted Contact with RV Outlet Nozzle

One of the challenges in the current reactor is the gap between the outlet nozzle of the Reactor Vessel (RV) and the outlet opening of the Core Support Barrel (CSB). This gap causes bypass flow, reducing the overall efficiency. To address this issue, RV and CSB designs were modified with various configurations. Through finite element analysis, this study evaluated the structural integrity and dynamic response of an RV and CSB with these modified designs. The structural integrity was assessed against ASME code to determine the limits of design parameter changes that met code requirements. Additionally, the natural vibration characteristics of the CSB and RV were analyzed to evaluate improvements in the seismic response by modal analysis. The findings revealed that the CSB design in the case of 3-degree slanted contact with the RV outlet nozzle provided the most optimized results. Moreover, modal analysis indicated a substantial enhancement in seismic response, with the dominant CSB mode frequencies increasing by 30%. This shift, from the 15–20 Hz range to the 20–30 Hz range, is especially noteworthy given the concentration of seismic energy within the 1–20 Hz band.

Assessment of Building Nondeterministic Dynamic Structural Behavior considering the Effect of Geometric Nonlinearity and Aerodynamic Damping

The objective of this research is to evaluate the dynamic structural response of tall buildings subjected to wind loads, taking into account the influence of geometric nonlinearity and aerodynamic damping. The project focuses on a steel-concrete composite structure with 48 floors and a height of 172.8 m, examining its response to wind non-deterministic dynamic actions. The building finite element model was developed based on the Finite Element Method (FEM), using the ANSYS computational program, and considering the soil-structure interaction effect, with the objective of obtaining a realistic representation of the dynamic behavior. The building dynamic response was obtained based on the displacement and acceleration values, determined with the consideration of a wind velocity range between 5 m/s (18 km/h) and 45 m/s (162 km/h). The findings of this study indicate that when the effect of geometric nonlinearity was incorporated into the analysis, the dynamic response of the investigated building exhibited notable discrepancies. The maximum differences observed in the horizontal translational displacements and accelerations were 30% and 45%, respectively. In contrast, the inclusion of aerodynamic damping had a negligible impact on the structural dynamic response, with maximum differences of 5% for displacements and 10% for accelerations.

Support vector regression model for the prediction of buildings’ maximum seismic response based on real monitoring data

Maximum drift ratio (MDR), one of the engineering demand parameters (EDPs), provides fundamental physical value for predicting building damage. Existing machine learning based prediction models mainly rely on numerical simulation data or structural experiments and are not appropriate for prediction of seismic response of real structures. The New Earthquake Data (NDE1.0) is the most comprehensive publicly available dataset of actual structural seismic response observations. Currently the prediction models using NDE1.0 are mainly based on linear or log-linear regression. In this study, based on the NDE1.0 flatfile, we develop a full-feature support vector regression (SVR) based MDR prediction model (SVR-MDR), treating all the available 41 characteristic parameters including structural information as input feature. To improve the model’s efficiency and practical applicability, we also establish a reduced-feature SVR model (RSVR-MDR) by selecting 10 fundamental parameters based on SHapley Additive exPlanations (SHAP) values and the accessibility of features. Our results demonstrate that SVR-MDR model outperform other machine learning models such as kernel ridge regression and decision tree models, and SVR-MDR and RSVR-MDR models outperform conventional loglinear regression and multinomial models, because SVR can map the complex nonlinear function of multiple variables and consider the available information of buildings especially the fundamental frequency. The proposed RSVR-MDR model have promising potential application for post-event seismic damage assessment and post-event emergency response in near real time.

Effect of soil profile-related parameters on seismic performance of ductile reinforced concrete building frames in California

Strong ground motions with specific site characteristics can lead to structural damage. Comprehending the effects of site characteristics on the dynamic response of structures is crucial for evaluating seismic performance and thereby implementing design that can mitigate potential damage. This study explores how the site characteristics, including the average shear wave velocity, soil depth to rock, and site period, influence the seismic response of reinforced concrete buildings. Soil column models were created using 319 soil profiles located in California and were employed to perform the nonlinear site response analysis of 80 rock motions to generate surface motions. Subsequently, low-to high-rise reinforced concrete moment-resisting frames with four, eight, twelve, and twenty stories that are representative of California were modeled to conduct nonlinear structural analyses. In this process, the influence of the three site characteristics on the response of the surface motions and structures was investigated. This investigation revealed that structural responses tend to increase when the average shear wave velocity ranges from 180 to 360 m/s or when the depth exceeds 135 m. Additionally, structures with a natural period exceeding 1 s were found to be more vulnerable as the number of stories increased. The outcomes will promote the development of seismic design methods based on different site characteristics.

End-to-End Simulation of Linerless Composite Pressure Vessels Using 3D Continuum Damage Models

Linerless composite pressure vessels, or type V pressure vessels, are gaining increased interest in the transportation industry because they offer improved storage volume and dry weight, especially for low-pressure cryogenic storage. Nevertheless, the design and manufacturing of this type of pressure vessel bring several challenges due to the inherent difficulties in the manufacturing process implementation, assembly, and related analysis of structural integrity due to the severe operating conditions at cryogenic temperatures that should be taken into consideration. In this work, a novel analysis procedure using a finite element model is developed to perform an end-to-end simulation of a linerless pressure vessel, including the relevant features associated with automated fiber placement manufacturing processes regarding thickness and tape profiles, followed by an analysis of the structural response under service conditions. The results show that residual stresses from manufacturing achieve values near 50% of the composite ply transverse strength, which reduces the effective ply transverse load carrying capacity for pressure loading. Transverse damage is triggered and propagated across the vessel thickness before fiber breakage, indicating potential failure by leakage, which was confirmed by hydrostatic tests in the physical prototype at 26 bar. The cryogenic condition analysis revealed that the thermal stresses trigger transverse damage before pressure loading, reducing the estimated leak pressure by 40%. These results highlight the importance of considering the residual stresses that arise from the manufacturing process and the thermal stresses generated during cooling to cryogenic conditions, demonstrating the relevance of the presented methodology for designing linerless cryogenic composite pressure vessels.

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

Vulnerability of structures designed with seismic provision due to explosions in mines

The effect of blast-induced ground vibration on structures was examined. The aim was to investigate the extent to which the strength attributed by seismic design can resist the effect of mine blasts, as both earthquakes and blasts generate lateral forces. The study was conducted to see whether and how blasts can be controlled such that seismic design of structures may suffice the purpose of withstanding mine blasts. The responses in the elastic and post-elastic regions were compared for implementation of the concept of performance-based design. The responses of structures were investigated for both single and sequential blasts. The results showed that sequential blast events are more damaging than earthquakes. On the other hand, medium- and long-period structures under a single blast event can withstand blast-induced vibration if designed as per seismic provisions. To safeguard structures under sequential blasts, it is recommended that the number of blast events is controlled. The safety of structures under blast can be determined by knowing the additional strength attributed from the seismic effect. This may help to decide whether separate design provisions for blast-induced ground motion are needed.

On the hysteretic bending behavior of slack metallic cables

Short and slack stranded metallic cables are encountered in several technical applications to connect different structures or different parts of the same structural system. A couple of relevant examples are provided by flexible-bus conductors used in high-voltage electrical substations or passive damping devices installed on overhead electrical lines, such as Bretelle dampers. Bending behavior of metallic cables is nonlinear and non-holonomic due to the onset and propagation of relative sliding phenomena between the wires. While taut suspended cables have been widely studied in the literature under the classic assumptions of small sag and perfect flexibility, whenever dealing with short and slack cables, the aforementioned hypotheses typically cease to be valid, and the bending stiffness contribution plays a significative role in the determination of the overall structural response. In the present paper, two different modeling strategies for the description of the bending behavior of short and slack stranded cables are presented. The first (discrete bending model) describes the cable as a composite structural element made of wires, which are individually modeled as curved elastic thin rods interacting through normal and tangential contact forces. The second (phenomenological bending model), instead, relies on a description of the cable bending process based on an application of the well-known Bouc-Wen hysteresis model. Applications of the proposed models are presented both at the cross-sectional and at the structural levels. The systematic comparison between theoretical and experimental results allows to assess the performance of the two proposed bending models when used with “nominal” values of the model parameters, which are estimated only on the base of the knowledge of the material and geometric properties of the strand. Moreover, a back-analysis of the model parameters is carried out to get an insight on internal mechanical parameters of the cable and on the overall cross-sectional bending response (e.g. bending stiffness values).

Real-Time Structural Health Monitoring of Bridges Using Convolutional Neural Network-Based Loss Factor Analysis for Enhanced Energy Dissipation Detection

This study introduces a novel method for real-time structural health monitoring (SHM) of bridges using a convolutional neural network (CNN) model that leverages loss factor analysis. As bridge structures deteriorate over time, often accelerated by operational loads, maintaining structural integrity and safety becomes critical. The proposed approach utilizes the concept of a loss factor, which represents the process of energy dissipation across different vibration states, as a key indicator of structural health. This factor is computed from vibration energy spectra, which include amplitude and frequency components, processed through the CNN model for high sensitivity to structural changes. The results demonstrate that the energy dissipation of the bridge during operation can be categorized into signals from three distinct sources: structural responses, defects-related indicators, and noise interference. By monitoring variations in the loss factor over time, the model effectively identifies early signs of structural deterioration, which is critical for timely maintenance interventions. The study also highlights the adaptability to different load conditions and environmental factors, ensuring robust performance in various operational scenarios. The findings underscore the potential of the CNN model to transform SHM practices by enhancing early defect detection, supporting preventive maintenance, and ultimately extending the lifespan of bridge infrastructure.

A novel design approach for structures with inerter systems based on non-stationary seismic excitations

Existing research predominantly focuses on developing design methods for the structural configuration of inerter systems. However, the authors find that these optimization methods often overlook the non-stationary characteristics associated with seismic response. Additionally, traditional approximation algorithms yield significant errors in non-stationary processes, resulting in inaccurate predictions of the structural responses with inerter systems, which compromises the effectiveness of the optimization designs. This paper proposes a novel approach that combines the parameters of the inerter system with a modified Vanmarcke approximation to obtain unified calculation formulas for inerter parameters. The accuracy and computational efficiency in solving spectral moments are crucial for the feasibility of this method. The study presents an efficient calculation method to accurately determine non-stationary response spectral moments of structures with inerter systems. Using the complex modal method (CMM) and pseudo-excitation method (PEM), a unified solution for structural responses under seismic actions is obtained. The quadratic decomposition of the power spectral density function (QD-PSDF) is employed to derive analytical solutions for response spectral moments and non-geometric spectral characteristics (NGSC). Substituting the obtained moment values into the parameter calculation formulas allows effective determination of the inerter system parameters. Finally, Finite Element Method (FEM) modeling verifies the validity and general applicability of this approach. The results demonstrate that the proposed method accounts for non-stationary characteristics of structures with inerter systems under seismic excitations, enhancing seismic design reliability and structural safety. Moreover, the obtained inerter system parameters at each floor effectively achieve the target performance while providing a broader range of design options for enhanced flexibility in system configuration.

Time-Domain Load Identification and Dynamic Displacement Inversion of Discharge Sluice in Large Hydropower Stations Based on the Conjugate Gradient Least Squares Iteration Algorithm

The identification of flow-induced vibration loads is the key to solving the vibration problem of hydraulic structures induced by high-speed water flow. In this study, a time-domain load identification method for discharge sluices in large hydropower stations based on the conjugate gradient least squares (CGLS) iteration algorithm is proposed. The main idea of this method is to first construct a mathematical model through the response signal and the structural modal parameters for solving the equivalent load acting on the sluice structure. Then, it uses the iterative regularization method to solve the ill-posed problem in the load identification process of the traditional time-domain method. Numerical simulations show that, in comparison to the traditional Tikhonov regularization algorithm, the CGLS algorithm is capable of reducing the relative error of the identified dynamic loads by approximately 100%, with higher accuracy and noise immunity. In this study, the CGLS algorithm is used to identify the external dynamic loads acting on the sluice structure during the flood discharge process of a large hydropower station in China. Three equivalent dynamic loads acting on the pier and the bottom plate are obtained. The positive analysis of the vibration response of the discharge structure is conducted using the equivalent load. The results show that the error between the measured vibration response signals and the vibration response signals obtained from the positive analysis is relatively minor, with the exception of a few individual measurement points. The displacement response mean square error is less than 10%, thereby substantiating the accuracy and validity of the CGLS load identification method proposed in this study in the actual engineering.

Compressive and Bending Properties of 3D-Printed Wood/PLA Composites with Re-Entrant Honeycomb Core

This study investigates the mechanical behavior of sandwich structures comprising a re-entrant honeycomb core structure created using wood/polylactic acid (PLA) filaments via fused deposition modeling (FDM) technology. The sandwich structures were manufactured with different face layer thicknesses (0 mm, 0.8 mm, and 1.6 mm) and various core topologies. Material characterizations included bending tests, compressive tests, and finite element analysis (FEA) to identify stress concentration areas. In-plane and out-of-plane re-entrant honeycomb core structure specimens were tested to examine the bending properties. In addition, flatwise and edgewise compressive tests were performed to investigate the structures' compressive properties. Furthermore, the modulus of elasticity for each specimen was determined using the finite element technique (FEM). The results reveal that increasing the thickness of the face layer significantly enhances the structure's resistance to bending forces. Furthermore, specimens with an in-plane orientation demonstrated better bending strength compared to those with an out-of-plane orientation due to increased material underloading. In flatwise compressive tests, specimens without a face layer exhibited the highest strength, attributed to their greater displacement. In contrast, edgewise compressive tests showed significant buckling behavior of the face sheet, the maximum stress increased proportionally with the thickness of the face layer, reaching its peak at a skin thickness of 1.6 mm. The findings are validated by ANSYS analysis, which closely mirrors the experimental results, providing insight into flexural modulus, modulus of elasticity, and stress concentration. These findings indicate that architected core structures could be efficiently utilized to improve bending/compressive characteristics and failure mechanisms, providing valuable insights into the mechanical response of sandwich structures for different industrial applications.

Exact H∞ optimization of dynamic vibration absorbers: Univariate-polynomial-based algorithm and operability analysis

H∞ optimization of dynamic vibration absorbers (DVAs) to minimize the maximum response amplitude of primary structures is a classic topic. The commonly used fixed-point method only provides approximate solutions requiring the primary structure is undamped. Instead, we perform exact optimization and investigate the less-reported parametric effects on optimization operability. To handle the known restrictions posed by grounded dampers, a typical DVA model mounted on a damped primary structure, with components connected to both the primary and the base, is considered. We explore three elaborated cases depending on the grounded dampers distributing in the primary structure and the DVA. Our findings reveal that the frequency responses of the primary structure with dual resonant peaks of equal height may not be the global optimum, and we establish a nontrivial necessary condition for operable exact optimization. Furthermore, we elucidate the effects of structural arrangements on the optimized results and provide design rules to maximize vibration suppression performance. The optimization follows the proposal of a so-called resultant-based algorithm that guarantees global optimum with high efficiency and a generalizable core by exclusively constructing univariate polynomial equations. This study contributes a systematic analysis framework alongside efficient calculation tools for exact optimization and DVA performance evaluation.