1,721,100 research outputs found
Corrigendum to “General reduced vehicle model for simulating truck-bridge pier collisions” [Dev. Built. Environ. 16 (2023) 100233] (Developments in the Built Environment (2023) 16, (S2666165923001151), (10.1016/j.dibe.2023.100233))
No full textThe authors regret there were two errors in the authors' affiliation in the published article. First, the affiliation of the first author (Daogang Ou) should only be the School of Civil Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China. Second, the corresponding author (Lin Chen) should have two affiliations; the first one should be: School of Civil Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China; and the second one should be: Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education, Hunan University, Changsha, 410082, China. The authors would like to apologise for any inconvenience caused
Investigation on effects of temperature and wind on expansion joints with monitoring data
No full textExpansion joints are important components in cable-supported bridges, which are prone to premature failures due to ever-changing harsh environment. In order to investigate the damage reasons in expansion joints, Structural Health Monitoring (SHM) data of a cable-stayed bridge and a suspension bridge are utilized, and effects of temperature and wind are studied. Firstly, correlation analysis is conducted between girder temperature and girder-end longitudinal displacement of the two bridges. Then, displacement characteristics are compared, which shows that the suspension bridge has a much larger cumulative girder-end displacement. Secondly, the girder end displacement of the cable-stayed bridge is investigated during a strong typhoon, to identify the influences of wind direction and wind speed. Finally, conclusions based on the investigation of expansion joints are presented. The SHM based analysis could provide insights for bridge owners to perform more reasonable maintenance
High-strain rate compressive behavior of Fiber-Reinforced Rubberized Concrete
No full textThe compressive mechanical properties of concrete-based materials are strongly affected by the presence of additions in the mix and load application velocity. Fiber-Reinforced Rubberized Concrete (FRRC) was recently proposed in the literature as a concrete-based material with the aim of obtaining a ductile material with reduced environmental burden and characterized by excellent energy absorption performances during impact loading. FRRC joins and balances the advantages and drawbacks of Fiber Reinforce Concrete (FRC) and Rubberized Concrete (RuC). However, its behavior has rarely been investigated under dynamic loadings, although gaining sufficient knowledge on their high strain rate behavior is crucial for their full-scale application. This study aims to investigate the high-strain rate compressive behavior of FRRC with fine rubber aggregates and micro-straight steel fibers. Tests were performed using conventional quasi-static loading with a compressive testing machine and high-strain rate tests with a Φ80-mm Split Hopkinson Pressure Bar (SHPB) for strain rates up to 200s−1. The experimental program comprises the characterization of Plain Concrete (PC), FRC, RuC, and FRRC with a full test matrix (a total of 192 specimens) covering fiber contents up to 1.5% and rubber volume substitution ratios up to 30%. The micro-scale characterization of the material using SEM scans provided a complete understanding of the observed macro-scale behavior. A high-speed camera was used to capture the cracking development processes. The measurements both for quasi-static and dynamic tests indicate that the addition of fibers improves the ductility or toughness with a slight increase in the compressive strength and the substitution with rubber aggregates significantly reduces the compressive strength with improved ductility or toughness. The combination of fiber and rubber (FRRC) leads to a combination of the previously described single marginal effects. The dynamic tests reveal the marked strain rate dependency, although specimens with large rubber volume substitution were more sensitive to the strain rate effect within the considered test range. Based on the test data, data-driven models for strength reduction factor (SRF) and dynamic increase factor (DIF) are proposed for different types of FRRC. The image-based waveform discussion provides evidence of the “double-peak” phenomenon highlighting the different features of the observed signals and damage evolution. Ultimately, this study indicates that FRRC has an excellent high-strain rate compressive behavior and can be a promising material to be employed to protect structures against impact and blast loads
Preliminary insights on the inelastic seismic response of structural systems under pulse-like ground motion
No full textNear-fault pulse-like seismic events exhibit a pulse in the velocity time history that mainly occurs in the strike-normal direction at locations towards which the earthquake rupture has propagated. The large damage potential associated with such seismic events is due to high displacement and velocity demands, together with the transmission of a large amount of energy in a relatively short time. In presence of specific geological conditions, they can also reveal unusual peaks of the spectral values in the long-period range. Additionally, it is well known that the intensity level of the vertical shaking close to the causative fault can be exceptionally high. Within this framework, the present study presents a preliminary sensitivity analysis of the inelastic response of structural systems under near-fault pulse-like ground motion accounting for the vertical component through the P-Delta effect for better understanding the damage potential of such seismic events and for supporting the development of proper design guidelines. First, some seismic records have been selected and processed. The dominant pulse embedded in the selected records and the corresponding pulse period value are derived
through a recent methodology based on the Variational Mode Decomposition technique. Several nonlinear dynamic analyses are then performed. Specifically, elastic and inelastic response spectra are first calculated taking into account the whole seismic signal and the dominant pulse only, without and with vertical seismic component and P-Delta effect. In doing so, acceleration, velocity, displacement and energy spectra are carried out and analyzed. The preliminary results here reported indicate that for large fundamental periods of the oscillator (e.g., larger than 3 s) the response can be significantly higher when the vertical component of the accelerogram and P-Delta effect are also taken into account.
Moreover, it is found that the nonlinear behavior of the oscillator can have a beneficial or detrimental effect. The outcomes of this preliminary analysis aim at providing useful insights toward a better characterization of the seismic demand in inelastic structural systems subjected to pulse-like seismic events
Modeling of glubam roof truss, parameter identification and updating based on parallel genetic algorithm
Full text linkThis research introduces an innovative approach to the design and simulation of bio-based laminated structures, specifically focusing on glue-laminated bamboo (glubam) used in roof trusses. Our study fills a critical gap by investigating the mechanical behaviors of bolted connections in bamboo-based structures, which have not been comprehensively studied before. We employ a dual-phase methodology: initially, cyclic tests on bolted steel to glubam joints assess their hysteretic behavior, followed by tests on glubam planar roof trusses to evaluate structural responses under practical conditions. Our novel contribution is the development of a simplified mechanical-based hysteretic model, incorporating connector and spring elements in series or parallel within the ABAQUS software. This model significantly improves on existing models by allowing for initial calibration through a parallel genetic algorithm (PGA), enhancing both accuracy and efficiency. Subsequent incorporation of this model into the simulation of truss joints enabled the creation of an advanced hybrid roof truss model within ABAQUS. The final stage of our research demonstrates the application of a PGA-based model-updating framework, which substantially increases the model's predictive accuracy. This work not only advances the understanding of structural behavior in bio-based construction materials but also introduces a robust framework for model updating that can be applied to other engineering simulations, contributing to more sustainable and resource-efficient construction practices
High-strain rate compressive behavior of Douglas fir and glubam
No full textUnderstanding the high-strain rate compressive behavior and related energy absorption performances of Douglas fir and glubam is crucial for the application of these materials under impact/blast loading. To this aim, quasi-static tests using a universal testing machine and dynamic tests using an expressly-designed aluminum Split-Hopkinson Pressure Bar (SHPB) apparatus were performed. A total of 90 specimens of Douglas fir and two types of glubam were tested to characterize the quasi-static and high-strain rate compressive characteristics covering a large range of strain rates from 2.2×10-3s-1 to around 1×103s-1. Two different directions were studied: along the fiber (longitudinal) and across the fiber (transverse). The compressive stress-strain curves were analytically described through two uniaxial phenomenological models taken from the literature. Using the fitted parameters of the phenomenological models, it is provided an original definition of the Dynamic Increase Factor (DIF). Finally, energy absorption performances are investigated. The results of this investigation show that Douglas fir and glubam are strain rate sensitive and this sensitivity highly depends on the loading direction
High-strain rate tension behavior of Fiber-Reinforced Rubberized Concrete
No full textThis paper investigates for the first time the high-strain rate splitting tension behavior of Fiber-Reinforced Rubberized Concrete (FRRC). Splitting tension tests were performed on Phi 100-mm specimens. Quasi-static tests were carried out using conventional quasi-static loading with a compressive testing machine and dynamic high-strain rate tests with a Phi 80-mm Split Hopkinson Pressure Bar (SHPB) for strain rates up to 10 s(-1). The experimental program comprises the characterization of Plain Concrete (PC), Fiber Reinforced Concrete (FRC), Rubberized Concrete (RuC), and FRRC with a full test matrix (a total of 240 specimens) covering fiber contents up to 1.5% and rubber volume substitution ratios up to 30%. A high-speed camera was used to capture the cracking development processes together with Digital Image Correlation (DIC). The addition of fibers enhances the deformation capacity with a marked increase in the tensile strength both for quasi-static and dynamic conditions while the substitution with rubber aggregates significantly reduces the tensile strength with a similar enhancement of the deformation capacity. For FRRC, a combination of the two effects was observed. FRC, RuC, and FRRC are characterized by marked strain rate dependency within the considered test range. Furthermore, data-driven models for compression and tension strength reduction factor (SRF(c )and SRFt) and tension Dynamic Increase Factor (DIF) are proposed for different types of FRRC. Finally, a discussion on the image-based damage development processes is provided based on the high-speed camera videos. This study indicates that FRRC has an excellent high-strain rate tension behavior reducing and controlling the crack propagation
Bio-based hybrid planar truss: Experimental testing, FE modeling and Bayesian model updating
No full textThis paper examines the cyclic behavior of a bio-based truss structure with slotted steel plate bolted connections through a comprehensive approach involving experimental testing, FE modeling, and Bayesian model updating. Experimental tests were performed on both connection and truss levels to determine the cyclic behavior. For the joint level, a total of four distinct joint configurations were tested to determine their axial hysteretic behavior. For the truss level, cyclic tests were carried out on four hybrid planar trusses composed of the four types of truss joints. To define the axial hysteretic behavior of the joints, a robust numerical model is first defined accounting for hysteretic behavior in OpenSees. The proposed model can capture sliding, contact, pinching, strength degradation, and failure behavior. A model reduction via parameter sensitivity analysis is first performed. A Bayesian parameter identification based on Sequential Monte Carlo method was performed based on cyclic truss joints tests. A model of the hybrid truss was developed in OpenSees by integrating the joints and elastic truss elements. The developed model underwent validation using various experimental parameters, including the hysteresis curve, relative displacement at joints, and strain values at each chord. To correct the errors and the bias, a Bayesian model updating framework based on the Sequential Monte Carlo method is proposed herein to deal with model uncertainty. The proposed framework enables the acquisition of highly precise predictions by incorporating global and/or local responses while appropriately accounting for model uncertainties
Mathematical Tools for the Seismic Analysis of Reinforced Concrete Structures: A Selected Review
No full textResponse spectrum analysis represents the preferential strategy to analyze and design civil engineering structures subjected to seismic actions. Nevertheless, most structural codes were developed by following hand computation-oriented philosophies so that their prescriptions can be hard to be implemented in finite element frameworks and often prevent the use of innovative strategies. This contribution presents a review of innovative tools focused on reinforced concrete framed structures aiming to establish a possible organic workflow for design procedures. Some pivotal issues typical of such a structural typology are hereby addressed, and particularly, global torsion and capacity checks in the presence of axial force–biaxial bending responses. This has been done by correlating innovative solutions such as torsional spectra, seismic envelopes, and limit analysis and by presenting a numerical procedure capable of performing capacity checks of reinforced concrete cross sections. The presented strategy aims to be a computationally efficient and exhaustive procedure to be used within the framework of finite element analysis
I due crolli del pont de Quebéc: una lezione da non dimenticare
No full textL’evoluzione della pratica professionale in Ingegneria Civile è stata spesso in passato il frutto di insuccessi, che hanno portato alla luce i limiti della prassi corrente ed innescato processi d’innovazione e ricerca. Nel 1887 si decise di costruire un ponte a sbalzo sul fiume San Lorenzo in Canada, simile al ponte ferroviario sul Firth of Forth in Scozia, con campata centrale di 549 m; la progettazione fu indirizzata verso una struttura meno massiccia e dunque più economica. La struttura subì due crolli, con una perdita complessiva di 88 vite umane, che portò ad una durata complessiva di realizzazione di oltre 30 anni. I due crolli hanno evidenziato errori connessi alla valutazione delle azioni, alla previsione di fenomeni di instabilità ed alla concezione di ridondanza strutturale. In questo lavoro viene riportata la storia della realizzazione del Pont de Québec, analizzando i risultati delle attività delle Commissioni di inchiesta e mostrando come le attuali conoscenze e norme contengono regole e prescrizioni che consentono ai progettisti di evitare collassi di questo tipo
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