Journal: Engineering Structures

Abbreviation

Eng. Struct.

Publisher

Elsevier

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ISSN

0141-0296

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Publications1 - 10 of 152
  • Fatigue performance of orthogonally reinforced concrete slabs: Experimental investigation
    Item type: Journal Article
    Spathelf, Christian A.; Vogel, Thomas (2018)
    Engineering Structures
  • Generative design of hierarchical truss structures with desired stiffness and strength: Recursive multiscale topology optimization based on powder bed fusion
    Item type: Journal Article
    Liu, Yizhuo; Hua, Hao; Jia, Zijian; et al. (2025)
    Engineering Structures
    The stiffness and strength of uniaxial compressive material can be equivalently realized by a hierarchical truss structure. This work fills the conceptual gap between weight minimization of single truss and the design of hierarchical truss metamaterial, resulting in the formulation of heterogeneous non-periodic structures. Multiscale topology optimization integrated with additive manufacturing (AM) leads to disruptive innovation in construction. The structural hierarchy plays a pivotal role in the creation of bulk material properties. Therefore, a systematic understanding of the cross-level behavior is critical. A rod with the desired stiffness and strength is implemented with an optimized truss with equivalent mechanical properties while using less material. Euler's critical problem is transformed into the global buckling problem of the truss at the lower level of hierarchy. The recursive algorithm constructs and simultaneously searches for the best structure of multi-level hierarchy. A series of uniaxial compression tests compared the differences between the theoretical model and the specimens produced by powder bed fusion (PBF). The truss joint geometry for PBF was tuned to approximate the stiffness and stability predicated by the mathematical model. Despite the AM imperfection, the statistical mechanical properties are consistent across specimens. 3D-printed trusses can be assembled by welding or bolting connections into larger structures in practice. Compared with solid material with equivalent stiffness and strength, the hierarchical fusiform trusses save significant amounts of material. The cross-level map between the mechanical behavior from neighboring levels of hierarchy facilitates the estimation of the upper bound of the levels of hierarchy.
  • Bearing stiffness in wood-to-wood compression joints
    Item type: Journal Article
    Wanninger, Flavio; Frangi, Andrea; Steiger, René (2015)
    Engineering Structures
  • Utilizing on-board sensing of passing train vehicles for virtual sensing of bridges
    Item type: Journal Article
    Siu, Ho Man; Filippitzis, Filippos; Stoura, Charikleia D.; et al. (2024)
    Engineering Structures
    This study proposes a bridge response reconstruction approach using exclusively measurements obtained from instrumented train vehicles with known properties. The approach relies on an Augmented Kalman Filter (AKF) technique to estimate contact forces without prior knowledge of rail profile irregularities. Furthermore, the proposed methodology addresses the challenge of accurate vehicle-bridge interaction (VBI) contact force estimation in the presence of rigid-body modes in the train model, by separating rigid-body from flexible modes, and establishing a state-space formulation that incorporates the vehicle dynamics of solely flexible modes. The study examines, by means of numerical simulations, the impact of measurement and model errors, vehicle speed, and rail irregularities on both contact force estimation and bridge response reconstruction. It also investigates sensor configurations that minimize the number of sensors required on the train and shows that acceleration at all wheels and strain of at least one primary suspension per bogie are necessary for accurate force estimation. The results emphasize the significant role of VBI in achieving accurate bridge response reconstruction. The estimated contact forces in combination with a bridge model allow the reconstruction of the bridge response through virtual sensing, providing valuable information on the bridge's health status.
  • Analysis and design recommendations for structures strengthened by prestressed bonded Fe-SMA
    Item type: Journal Article
    Li, Lingzhen; Wang, Sizhe; Chatzi, Eleni; et al. (2024)
    Engineering Structures
    Previous studies have demonstrated a great potential of prestressed strengthening of structures employing iron-based shape memory alloys (Fe-SMAs). A bonded Fe-SMA strengthening solution with partial activation has been proposed. However, an analytical model for assessing the strengthening efficiency was lacking, due to the unique nature of the employed prestressing mechanism involving heating. In this study, a symmetric strengthening model and an asymmetric strengthening model are developed to analyze the prestress level in steel and glass beams and plates strengthened by bonded Fe-SMA strips. The asymmetric strengthening model is then modified to analyze reinforced concrete (RC) beams strengthened by embedded Fe-SMA rebars. Recovery stress at different activation temperatures, the influence of the activation temperature on the adhesive bond, as well as the prestress loss resulting from the deformation of substrate elements and adhesive joints are taken into account. The predicted strains and deflections in the parent structure closely approximate the experimental measurements that appear in current literature. A parametric study and a sensitivity analysis are then conducted to assess the impact of the four influential features on the final prestress level, and their impact is ranked in the following order: recovery stress ≈ Fe-SMA width > activation length > bonded anchorage length. Based on these findings, a design strategy, in line with Eurocode 0, for the bonded/embedded Fe-SMA strengthening system is proposed. Finally, some perspectives on potential areas for future research are offered.
  • Proposal for a stress modification factor for the fatigue design of flange thickness transitions in welded girders
    Item type: Journal Article
    Taras, Andreas; Unterweger, Harald (2013)
    Engineering Structures
    Thickness steps or transitions are often used in flanges of bridge girders in order to adapt the bending resistance of the cross-sections to variable bending moment distributions. The sudden change of the stiffness distribution within the cross-section at these details causes additional local forces and stresses, which cannot be properly taken into account by classical beam-theoretical calculations, and which lead to a deterioration of the fatigue performance of the welded details at and around the transition. A modification of nominal stresses – e.g. by the use of an appropriate stress concentration factor kf – is therefore required in order to obtain safe joint designs with respect to fatigue. The stress-raising effects at flange thickness transitions are of a similar nature as the ones caused by plate or angular misalignments, for which kf-factors are provided in the literature. However, the specific configuration of flanges in – often quite deep – bridge girders causes additional (beneficial or detrimental) effects that have not been sufficiently studied before, and which are currently not correctly considered in common design practice. This paper discusses the characteristic local load-carrying behaviour and stress distribution in flange thickness transitions of welded I-section bridge girders, which were studied by numerical, experimental and analytical means. The paper furthermore introduces a new, accurate and mechanically coherent analytical formulation of kf-factors for the modification of nominal longitudinal stresses in bridge girder flanges; these new kf-factors could be used for practical fatigue design verifications. The possibility of including further amendments to the proposed formulation in order to take into account for the effects of additional unintentional misalignment or dimensional tolerances at the butt weld were also discussed. Finally, an outlook is given on the need to also consider additional stress concentration factors for shear in the fillet welds in the areas surrounding a thickness transition. © 2013 Elsevier Ltd.
  • Bending behaviour of Composite Steel Truss in Concrete (CSTC) beams in fire
    Item type: Journal Article
    Vigneri, Valentino; Di Nunzio, Giuseppe; Taras, Andreas (2025)
    Engineering Structures
    This study investigates the fire resistance of Composite Steel Truss and Concrete (CSTC) beams through experimental testing, numerical modelling, and analytical formulations. Two four-point bending tests on 4.24 m long CSTC beams were carried out under standard fire conditions with a utilization factor of ca. 0.5: one configuration assembled with embedded reinforcing bars (F1), and another with round chords welded to the bottom plate (F2). The test F1 demonstrated that the reinforcing bars improve the bending resistance under prolonged fire exposure, leading to more than 120 min of fire resistance. The second specimen (F2) underwent bending failure after ca. 58 min. Finite element models were developed and validated against the experimental results via thermal and thermomechanical analyses to extend the experimental findings. Based on additional heat transfer analyses, formulae were proposed to predict the temperature of the reinforcement bars and the effective concrete areas for different fire curves and exposure periods. Additionally, thermomechanical analyses were used to track the evolution of axial forces in the steel members and stress flow in concrete, providing insights into the beam load-bearing mechanisms at elevated temperatures. A strut-and-tie model was subsequently proposed at ambient and elevated temperatures, highlighting the role of concrete compression struts in shear transfer alongside the steel truss mechanism. Finally, an easy-to-use design methodology combining the given analytical formulations with existing design guidelines on composite structures was proposed for determining the bending resistance of CSTC beams in the fire situation.
  • Editorial for Special Issue on “Wind Turbine Structures”
    Item type: Other Journal Item
    Zhu, Songye; Chatzi, Eleni; Bi, Kaiming; et al. (2024)
    Engineering Structures
  • Damage estimation in reinforced concrete buildings from induced earthquakes in Brazil
    Item type: Journal Article
    Silva, Andréia; Pereira, Eduardo M.V.; Pita, Gonzalo L.; et al. (2021)
    Engineering Structures
    Large reserves of unexploited shale gas in Brazil have recently been reported, some of them located near densely populated cities. Obviously, the possibility for commercial exploitation of these resources has suddenly arisen, although such activities have been found to be correlated with the occurrence of induced earthquakes in other parts of the word. As in many other countries, in Brazil, making provision for the eventual effects of induced seismicity was not a consideration when the seismic standards were developed. Today, we do know about the possibility of induced earthquakes occurring, but the knowledge about the potential extent of the resulting damages remains imperfect, at best. Consequently, studies such as the one presented here, and another recently completed, are a first step to improve the knowledge base of the potential risk of induced earthquakes in Brazil for devising adequate risk-control mechanisms. This study assesses the probabilistic response to induced earthquakes of prevalent low-rise engineered reinforced concrete buildings in Brazil. Fragility functions are developed, considering structural and non-structural damage, and including the structural contribution of masonry infills. It was found that, when infill walls do not work as structural components, structural damage is more likely to occur, and conversely, when they do, non-structural damage is significant. The latter effect is produced by the reduction of the natural period of vibration, which exacerbates damage on interior components sensitive to floor acceleration. The likelihood of non-structural damage is not negligible and thus should be considered by decision makers. © 2021 Elsevier
  • A novel device for a vertical rocking isolation system with uplift allowed for industrial equipment and structures
    Item type: Journal Article
    Reyes, Sergio; Almazán, José L. (2020)
    Engineering Structures
    In this paper, a novel device called the “ISO3D-2G” is proposed for a three-dimensional vertical rocking isolation (VRI) system. The VRI system works by isolating critical vibration sources, e.g., earthquake events and operational high-frequency vibrations. In this work, only its performance as a seismic isolation system is studied. The ISO3D-2G is made of a steel structure and an elastomeric rubber system, offering improved properties as compared to previous versions of the device. The device is manufactured at a full scale and is experimentally tested. To represent the vertical non-linear hysteretic behavior of the device, a numerical model called the hyperelastic Bouc-Wen (HBW) model is developed. The HBW model combines a hyperelastic component (represented in this work by a third-order Ogden model) and a hysteretic component (represented by a modified BW model). The simply supported horizontal behavior of the device is represented through a non-linear 2D frictional hysteretic model. The HBW model is calibrated to fit the experimental data obtained in the test, and guidelines are provided for understanding and manually calibrating the model. The dynamic performance of the system is analyzed using time-history analyses with four records (three non-impulsive records and one impulsive record). Equations are presented for the motion of the system. For the three non-impulsive seismic records, the observed behavior was similar to that in conventional lateral isolation systems. Horizontal force reduction ratios between 7.4 and 10.9 were obtained. The maximum shear base remained below 23% of the total weight of the structure, even considering the three components of the ground motion. In addition, vertical force reduction ratios between 2 and 3.8 were obtained, demonstrating that the vertical isolation effect was satisfactory. However, for an impulsive seismic record, there was a significant change in the patterns of behavior, owing to the significant uplift of two of the four devices. Despite this, the structure remained stable, and the lateral isolation effect was preserved. Finally, it was concluded that using vertically flexible devices with high damping in the base of structures to generate a rocking isolation mechanism is an effective approach to reducing the seismic demand, even though the isolated modes of the structure do not take periods longer than 2.0 s. Although there was no lateral translation at the base, the VRI system isolated the structure by allowing lateral and vertical displacement of the center of mass.
Publications1 - 10 of 152