ORCID Profile
0000-0002-5702-6119
Current Organisation
Hong Kong Polytechnic University
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Civil Engineering | Structural Engineering | Dynamics, Vibration and Vibration Control | Earthquake Engineering
Civil Construction Design | Oil and Gas Exploration | Expanding Knowledge in Engineering | Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Technology |
Publisher: Elsevier BV
Date: 09-2021
Publisher: Springer Science and Business Media LLC
Date: 16-08-2022
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 09-2013
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 11-2017
Publisher: Elsevier BV
Date: 08-2021
Publisher: Springer Science and Business Media LLC
Date: 12-06-2022
DOI: 10.1007/S10518-022-01436-6
Abstract: Mortar-less construction with interlocking bricks has many advantages, such as improved construction efficiency and relatively low requirements on labour skills. Nevertheless, the seismic performance of interlocking brick structures is not well understood yet. In this paper, laboratory tests and numerical modelling are carried out to investigate the seismic behaviour of interlocking brick walls. Laboratory shaking table tests are performed on a scaled reinforced mortar-less interlocking brick wall. The response and damage modes under in-plane seismic loading are investigated. A detailed numerical model is then generated and validated with the laboratory testing data. Unlike the conventional masonry wall that diagonal shear damage governs the failure, the interlocking brick wall exhibits rocking responses, whose damage is mainly at the two bottom corners of the wall. Full-scale interlocking brick walls are then modelled and compared with conventional concrete masonry unit (CMU) walls bonded by mortar. Comparisons are made between the seismic resistances and damage modes of the two walls. The influences of ground motion intensities, vertical components of seismic excitations and different seismic time histories on the seismic behaviour of the interlocking brick wall are examined. It is found that the interlocking brick wall has a higher seismic resistance capacity than the conventional CMU wall. Inter-brick friction is the main energy dissipation mechanism in the interlocking brick wall. Because of the rocking response, vertical component of the ground motion significantly influences the damage of interlocking brick wall. The interlocking brick wall is insensitive to velocity pulses of ground motions due to its relatively high natural frequency.
Publisher: Elsevier BV
Date: 10-2019
Publisher: SAGE Publications
Date: 28-07-2017
Abstract: Pounding and unseating damages to bridge superstructures have been commonly observed in many previous major earthquakes. These damages can essentially attribute to the large closing or opening relative displacement between adjacent structures. This article carries out an experimental study on the pounding responses of adjacent bridge structures considering spatially varying ground motions using a shaking table array system. Two sets of large-scale (1:6) bridge models involving two bridge frames were constructed. The bridge models were subjected to the stochastically simulated ground motions in bi-direction based on the response spectra of Chinese Guideline for Seismic Design of Highway Bridge for three different site conditions, considering three coherency levels. Two types of boundary conditions, that is, the fixed foundation and rocking foundation, were applied to investigate the influence of the foundation type. In addition, a detailed three-dimensional finite element model was constructed to simulate an experimental case. The nonlinear material behavior including strain rate effects of concrete and steel reinforcement is included. The applicability and accuracy of the finite element model in simulating bridge pounding responses subjected to spatially varying ground motions are discussed. The experimental and numerical results demonstrate that non-uniform excitations and foundation rocking can affect the relative displacements and pounding responses significantly.
Publisher: Hindawi Limited
Date: 12-02-2020
DOI: 10.1002/STC.2529
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 11-2019
Publisher: Hindawi Limited
Date: 15-05-2019
DOI: 10.1002/STC.2368
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 02-2018
Publisher: Elsevier BV
Date: 04-2021
Publisher: Elsevier BV
Date: 10-2017
Publisher: World Scientific Pub Co Pte Lt
Date: 13-01-2020
DOI: 10.1142/S0219455420500236
Abstract: This paper investigates the seismic performance of bridges installed with a sliding-lead rubber bearing (LRB) isolation system subjected to near-fault earthquakes. A three-span continuous bridge isolated with sliding-LRB system is used as an ex le. Nonlinear time history analyses are conducted to investigate the sensitivity effects of isolation period, friction coefficient and sliding displacement limit on the bridge responses. The responses of the sliding-LRB system are compared with those of the conventional LRB system. The results show that the base forces of the piers can be reduced by employing proper friction coefficients. However, the residual displacement of the sliding-LRB system may be larger compared with that of the conventional LRB system. To overcome this disadvantage, an improved solution to reduce the residual displacement is proposed with its effectiveness investigated. It was also demonstrated that the residual displacement and peak displacement can be effectively reduced by employing the shape memory alloy devices in the sliding-LRB system without significantly increasing the base forces.
Publisher: Elsevier BV
Date: 11-2013
Publisher: American Society of Civil Engineers (ASCE)
Date: 09-2018
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 04-2020
Publisher: Springer Science and Business Media LLC
Date: 21-09-2020
Publisher: World Scientific Pub Co Pte Lt
Date: 06-2019
DOI: 10.1142/S0219455419500561
Abstract: Failures of transmission tower-line systems have frequently occurred during large earthquakes. It is essential to control the excessive vibrations of transmission tower-line systems to ensure their safe operation in such events. This paper numerically investigates the effectiveness of using a novel bidirectional pounding tuned mass d er (BPTMD) to control the seismic responses of transmission tower-line system when subjected to earthquake ground motions. A finite element model of a typical transmission tower-line system with BPTMD is developed using the commercial software ABAQUS, with the accuracy of the results verified against a previous study. The seismic responses of the system with and without BPTMD are calculated. For comparison, the control effect of using the conventional bidirectional tuned mass d er is also calculated and discussed. Finally, a parametric study is performed to investigate the effects of the mass ratio, seismic intensity, gap size and frequency ratio on the seismic response of the system, while optimal design parameters are obtained.
Publisher: Elsevier BV
Date: 04-2022
Publisher: SAGE Publications
Date: 07-01-2022
DOI: 10.1177/13694332211050977
Abstract: Multiple vibration modes of an engineering structure might be excited by earthquake ground motions. Multiple tuned mass d ers (MTMDs) are widely used to control these multi-mode vibrations. However, in the commonly used MTMD system, the mass element in each tuned mass d er (TMD) is normally assumed to be the same. To improve the performance of MTMDs for seismic-induced vibration control, non-uniform MTMD masses are adopted in the present study to improve the mass utilization of TMD, and a location factor is proposed to determine the best location of each TMD in the MTMD system. The effectiveness of the proposed method is validated through numerical study. The results show that the proposed method effectively reduces the seismic responses of the structure induced by multiple vibration modes.
Publisher: Elsevier BV
Date: 03-2020
Publisher: World Scientific Pub Co Pte Ltd
Date: 25-04-2022
DOI: 10.1142/S0219455422501358
Abstract: With the increment of cable length, long stay cables are prone to experience high-mode vortex-induced vibrations (VIVs) at normal wind velocities, and the VIV-prone mode range also becomes wider. Existing d ers cannot supply sufficient d ing for such a wide range of high-modes. Inerter-based d ers (IBDs), which take advantage of the two-terminal inertial device dubbed inerter, have been proved to have a better control performance than conventional d ers. However, existing studies on IBDs only focused on the first several cable modes, which cannot cover the wide range of VIV-prone modes of long stay cables. The high-mode and multi-mode VIV control by using IBDs is investigated in this study. The governing equations of the cable-IBD systems under VIV are first established. The control efficiency of the IBDs and the influence of optimum design strategies are compared. The use of two IBDs to further enhance the control efficiency is also discussed. The results show that a three-element IBD in this study is quite effective for high-mode and multi-mode VIV control of long stay cables. Moreover, the multi-mode control efficiency can be further improved through using two IBDs. The results in this study can guide the design of IBDs for VIV control of long stay cables.
Publisher: Informa UK Limited
Date: 19-03-2018
Publisher: Springer Science and Business Media LLC
Date: 06-11-2016
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 03-2015
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 09-2021
Publisher: Wiley
Date: 2009
DOI: 10.1002/EQE.943
Publisher: Elsevier BV
Date: 12-2018
Publisher: SAGE Publications
Date: 28-07-2016
Abstract: Base isolation techniques have been extensively used to improve the seismic performance of the bridge structures. The decoupling of the bridge decks from the piers and abutments using rubber isolator could result in significant reduction in seismic forces transmitted to the bridge substructures. However, the isolation devices could also increase the deck displacement and thus enhance the possibility of pounding and unseating damage of bridge decks. Moreover, previous investigations have shown that pounding and unseating damages on isolated bridges exacerbate due to the spatial variation in earthquake ground motions. Recent earthquakes revealed that isolation bearing could also be damaged due to the excessive movements of decks during large earthquake events. This study proposes the use of rotational friction hinge d ers to mitigate the damages that could be induced by large displacement of bridge decks, particularly focusing on pounding and unseating damages and bearing damages. The device is capable of providing large hysteretic d ing and the cost of installing the devices is relatively economical. This article presents numerical investigations on the effectiveness of these devices on a typical Nepalese simply supported bridge subjected to spatially varying ground motions. The results indicate that rotational friction hinge d ers are very effective in mitigating the relative displacement and pounding force, as well as controlling the bearing deformation and pier drift. It is also revealed that the effectiveness of the device is not significantly affected by small changes in the slip forces thus, small variations in the optimum slip forces during the lifetime of the bridge do not warrant any adjustment or replacement of the device.
Publisher: Elsevier BV
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 07-2018
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 04-2027
Publisher: Informa UK Limited
Date: 17-12-2019
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 03-2019
Publisher: Elsevier BV
Date: 07-2019
Publisher: World Scientific Pub Co Pte Ltd
Date: 03-2019
DOI: 10.1142/S0219455419500226
Abstract: In the present paper, a practical superposition method is proposed for complex load-dependent Ritz (CLDR) vectors for use in the dynamic analysis of nonclassically d ed systems. In particular, an algorithm for CLDR vector generation is developed and the CLDR vectors are calculated in the physical space, instead of the state space, to reduce the computational effort and storage space, while improving the stability of the algorithm. Moreover, single CLDR vector (i.e. using only one starting vector) and block CLDR vector (i.e. using multi-starting vectors) generation procedures are introduced for the uni and multidirectional loading patterns respectively, and the latter is applied to the system with repeated natural frequencies. In addition, a criterion, which is based on the spatial load distribution, is proposed to determine a proper number of the CLDR vectors prior to their use in the dynamic analysis. Two numerical ex les are provided to illustrate the accuracy and efficiency of the proposed method. Also, the performance of the cut-off criterion is presented and 10% error or less in the participation loading distribution is recommended for practical applications.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Informa UK Limited
Date: 30-09-2009
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 07-2019
Publisher: Informa UK Limited
Date: 17-01-2019
Publisher: Elsevier BV
Date: 07-2019
Publisher: Elsevier BV
Date: 02-2020
Publisher: SAGE Publications
Date: 10-2013
DOI: 10.1260/1369-4332.16.10.1799
Abstract: The construction of concrete filled steel tubular (CFST) arch bridge has become widespread all over the world and especially in China since 1990. This paper studies the nonlinear seismic response of a CFST arch bridge on a canyon site subjected to multi-component spatially varying ground motions. The three-dimensional (3D) finite element (FE) model of the CFST arch bridge is developed with consideration of the material and geometric nonlinearities of the arch ribs. The spatially varying ground motions with consideration of wave passage effect, coherency loss effect and local site effect are stochastically simulated based on the combined one-dimensional (1D) wave propagation theory and spectral representation method. The effects of multi-component earthquake excitations, spatial variations of ground motions and varying site conditions on the seismic response of the CFST arch bridge are analysed. Numerical results show that for a reliable seismic analysis of a CFST arch bridge, multi-component earthquake excitations with consideration of ground motion spatial variations and local soil conditions should be considered.
Publisher: Springer Science and Business Media LLC
Date: 02-08-2019
Publisher: Elsevier BV
Date: 07-2022
Publisher: Elsevier BV
Date: 04-2020
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 07-2022
Publisher: World Scientific Pub Co Pte Lt
Date: 08-2018
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 2013
Publisher: Elsevier BV
Date: 02-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 07-2020
Publisher: American Society of Civil Engineers (ASCE)
Date: 12-2018
Publisher: Hindawi Limited
Date: 27-05-2022
DOI: 10.1002/STC.3016
Publisher: Elsevier BV
Date: 05-2019
Publisher: Elsevier BV
Date: 06-2017
Publisher: Springer Science and Business Media LLC
Date: 04-2020
Publisher: Frontiers Media SA
Date: 10-11-2022
DOI: 10.3389/FNAGI.2022.1019296
Abstract: Alzheimer’s disease (AD) is an insidious disease. Its distinctive pathology forms over a considerable length of time without symptoms. There is a need to detect this disease, before even subtle changes occur in cognition. Hallmark AD biomarkers, tau and amyloid-β, have shown promising results in CSF and blood. However, detecting early changes in these biomarkers and others will involve screening a wide group of healthy, asymptomatic in iduals. Saliva is a feasible alternative. S le collection is economical, non-invasive and saliva is an abundant source of proteins including tau and amyloid-β. This work sought to extend an earlier promising untargeted mass spectrometry study in saliva from in iduals with mild cognitive impairment (MCI) or AD with age- and gender-matched cognitively normal from the South Australian Neurodegenerative Disease cohort. Five proteins, with key roles in inflammation, were chosen from this study and measured by ELISA from in iduals with AD ( n = 16), MCI ( n = 15) and cognitively normal ( n = 29). The concentrations of Cystatin-C, Interleukin-1 receptor antagonist, Stratifin, Matrix metalloproteinase 9 and Haptoglobin proteins had altered abundance in saliva from AD and MCI, consistent with the earlier study. Receiver operating characteristic analysis showed that combinations of these proteins demonstrated excellent diagnostic accuracy for distinguishing both MCI (area under curve = 0.97) and AD (area under curve = 0.97) from cognitively normal. These results provide evidence for saliva being a valuable source of biomarkers for early detection of cognitive impairment in in iduals on the AD continuum and potentially other neurodegenerative diseases.
Publisher: Springer Science and Business Media LLC
Date: 09-09-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 04-2020
Publisher: Elsevier BV
Date: 03-2018
Publisher: Informa UK Limited
Date: 16-11-2017
Publisher: Elsevier BV
Date: 08-2022
Publisher: Wiley
Date: 20-02-2012
DOI: 10.1002/EQE.2168
Publisher: Wiley
Date: 23-11-2010
DOI: 10.1002/EQE.1076
Publisher: Wiley
Date: 22-11-2011
DOI: 10.1002/EQE.1077
Publisher: Elsevier BV
Date: 05-2019
Publisher: American Society of Civil Engineers (ASCE)
Date: 11-2022
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 07-2019
Publisher: Elsevier BV
Date: 02-2023
Publisher: SAGE Publications
Date: 04-2013
DOI: 10.1260/1369-4332.16.4.619
Abstract: Previous studies of pounding responses of adjacent bridge structures under seismic excitation were usually based on the simplified lumped mass model or beam-column element model. Consequently, only 1D point to point pounding, which is usually in the longitudinal direction of the bridge, could be considered. In reality, pounding could occur along the entire surfaces of the adjacent bridge structures. Moreover, spatially varying transverse ground motions generate torsional responses of bridge decks and these responses may cause eccentric poundings. That is why many pounding damages occurred at corners of the adjacent decks as observed in almost all previous major earthquakes. A simplified 1D model cannot capture torsional response and eccentric poundings. To more realistically investigate pounding between adjacent bridge structures, a two-span simply-supported bridge structure located at a canyon site is established with a detailed 3D finite element model in the present study. Spatially varying ground motions in the longitudinal, transverse and vertical directions at the bridge supports are stochastically simulated as inputs in the analysis. The pounding responses of the bridge structure under multi-component spatially varying ground motions are investigated in detail by using the finite element code LS-DYNA. Numerical results show that the detailed 3D finite element model clearly captures the eccentric poundings of bridge decks, which may induce local damage around the corners of bridge decks. It demonstrates the necessity of detailed 3D modelling for a more realistic simulation of pounding responses of adjacent bridge decks to earthquake excitations.
Publisher: Informa UK Limited
Date: 16-04-2022
Publisher: Elsevier BV
Date: 10-2017
Publisher: CRC Press
Date: 25-08-2017
Publisher: Elsevier BV
Date: 10-2015
Publisher: Springer Science and Business Media LLC
Date: 20-02-2019
Publisher: World Scientific Pub Co Pte Lt
Date: 27-04-2016
DOI: 10.1142/S0219455415500108
Abstract: This paper studies the time-dependent seismic fragility of reinforced concrete bridges with chloride induced corrosion under spatially varying ground motions. The time-varying characteristic of the chloride corrosion current density and the uncertainties related to the structural, material and corrosion parameters are both considered in the probabilistic finite element modeling of the ex le RC bridge at different time steps during its life-cycle. Spatially varying ground motions at different bridge supports are stochastically simulated and used as inputs in the fragility analysis. Seismic fragility curves of the corroded RC bridge at different time steps are generated using the probabilistic seismic demand analysis (PSDA) method. Numerical results indicate that both chloride induced corrosion and ground motion spatial variations have a significant effect on the bridge structural seismic fragility. As compared to the intact bridge, the mean peak ground accelerations (PGAs) of the fragility curves of the RC bridge decrease by approximately 40% after 90 years since the initiation of corrosion. Moreover, the effect of ground motion spatial variations changes along with the process of chloride induced corrosion owing to the structural stiffness degradation. Neglecting seismic ground motion spatial variations may not lead to an accurate estimation of the lifetime seismic fragility of RC bridges with chloride induced corrosion.
Publisher: World Scientific Pub Co Pte Lt
Date: 08-2018
DOI: 10.1142/S0219455418400059
Abstract: Pipe-in-pipe (PIP) system can be considered as a structure-tuned mass d er (TMD) system by replacing the hard centralizers by the softer springs and dashpots to connect the inner and outer pipes. With properly designed connecting devices, PIP system therefore has the potential to mitigate the subsea pipeline vibrations induced by various sources, such as earthquake or vortex shedding. This study proposes using rotational friction hinge d ers with springs (RFHDSs) to connect the inner and outer pipes. The rotational friction hinge d ers (RFHDs) are used to absorb the energy induced by the external vibration sources and the springs are used to provide the stiffness to the TMD system and to restore the original locations of the inner and outer pipes. To investigate the effectiveness of this new design concept, detailed three-dimensional (3D) finite element (FE) model of the RFHD is developed in ANSYS and the hysteretic behavior of RFHD is firstly studied. The calculated hysteretic loop is then applied to the 3D PIP FE model to estimate the seismic responses. The effectiveness of the proposed system to mitigate seismic induced vibrations is examined by comparing the seismic responses of the proposed system with the conventional PIP system. The influences of various parameters, such as the preload on the bolt, the friction coefficient and the spring stiffness, on the RFHD hysteresis behavior and on the seismic responses of PIP system are investigated and some suggestions on the RFHDS design are made.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 02-2016
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 10-2021
Publisher: SAGE Publications
Date: 30-06-2018
Publisher: Hindawi Limited
Date: 29-09-2021
DOI: 10.1002/STC.2860
Publisher: SAGE Publications
Date: 29-03-2022
Publisher: Elsevier BV
Date: 04-2023
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2022
Publisher: Elsevier BV
Date: 2018
Publisher: SAGE Publications
Date: 06-2011
DOI: 10.1260/1369-4332.14.3.457
Abstract: This paper studies the nonlinear responses of a coupled transmission towerline system on a heterogeneous site subjected to multi-component spatially varying ground motions. The three-dimensional finite element model of the transmission tower-line system is established with consideration of the geometric nonlinearity of the transmission lines. The spatial variation of ground motions associated with the wave passage, coherency loss and local site effects are considered. The spatial ground motions on ground surface are derived by modelling the base rock motion propagating through the local soil sites. The base rock motions are assumed consisting of out-of-plane and in-plane waves and are simulated stochastically based on an empirical coherency loss function and the filtered Tajimi-Kanai power spectral density function. The effects of multi-component, spatial variations of ground motions and varying site conditions at multiple tower foundations on seismic response of the transmission tower-line system are analysed. The study reveals that for a reliable seismic response analysis and safe and economic seismic resistance design of transmission tower-line systems, the multi-support and multi-component earthquake excitations with consideration of the effects of local site conditions on ground motion spatial variations should be considered.
Publisher: Elsevier BV
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 19-03-2019
Publisher: Elsevier BV
Date: 07-2012
Publisher: Elsevier BV
Date: 2023
Publisher: SAGE Publications
Date: 21-05-2022
DOI: 10.1177/13694332221104282
Abstract: Precast segmental columns have attracted wide attentions in bridge construction industry recently due to its ability to accelerate construction speed, improve construction quality and reduce environmental impact. It is of great practical importance to study the seismic performances of segmental columns, and many experimental and numerical studies have been performed. However, most previous studies focused on segmental column itself, the research on the seismic performance of a whole bridge structure supported by precast segmental columns is very limited. In particular, no systematic studies have been performed to investigate the seismic performances of segmental columns-supported bridges subjected to near-fault (N-F) ground motions (GMs). To bridge this research gap, the seismic responses of three bridge structures (i.e. a segmental columns-supported bridge, a bridge supported by segmental columns with internal energy dissipation bars, and a conventional bridge supported by monolithic columns) subjected to four types of earthquake ground motions (i.e. a N-F GM with fling-step (F-S) effect, a N-F GM with forward-directivity (F-D) effect, a non-pulse-like N-F GM, and a typical far-field (F-F) GM are investigated and compared in the present study based on the validated numerical models developed in ABAQUS. The influences of permanent ground displacement in the F-S ground motion and pulse period are also systematically investigated. The numerical results demonstrate that the permanent ground displacement in the N-F ground motions has very different effects on the segmental-columns supported bridge and monolithic columns supported bridge.
Publisher: Elsevier BV
Date: 07-2015
Publisher: Informa UK Limited
Date: 20-04-2017
Publisher: Informa UK Limited
Date: 31-05-2017
Publisher: Elsevier BV
Date: 2020
Publisher: MDPI AG
Date: 03-06-2022
Abstract: The effect of triple helical grooves on the suppression of vortex-induced vibration (VIV) of a circular cylinder was investigated experimentally in a wind tunnel over Reynolds number in the range of 1 × 104 Re 4 × 104. It was found that the helical grooves were effective in suppressing VIV with the peak litude reduction of approximately 36%. In addition, the lock-on region was also reduced. To explore the mechanism for the suppression of VIV, experiments on flow structures for a stationary grooved cylinder were also conducted in a wind tunnel at a free stream velocity U∞ of 4.37 m/s, corresponding to a Reynolds number based on the bare cylinder diameter of about 3500. The data were then analyzed using the phase-averaged method to evaluate the coherent vortex structures in the wakes. The results for the stationary grooved cylinder showed that the grooves weakened vortex shedding in the near wake. In addition, the grooves also reduced the drag coefficient by 6.6%. These results help explain the reduction of VIV using helical grooves.
Publisher: SAGE Publications
Date: 04-2015
DOI: 10.1260/1369-4332.18.4.453
Abstract: Vertical earthquake loading is normally regarded not as important as its horizontal components and are not explicitly considered in many seismic design codes. However, some previous severe near-fault earthquakes reveal that the vertical ground motion component can be much larger than the horizontal components and may cause serious damage to the bridge structures. This paper theoretically investigates the vertical pounding responses of a two-span continuous bridge subjected to the severe near-fault vertical ground motions. The bridge is simplified as a continuous beam-spring-rod model. The structural wave effect and the vertical pounding between the bridge girder and the supporting bearing are considered, and the theoretical solutions of bridge seismic responses are derived from the expansion of transient wave functions as a series of eigenfunctions. The effects of vertical earthquake and vertical pounding on the bridge bearing, girder and pier are investigated. The numerical results show that the severe vertical earthquake loading may cause the bridge girder to separate from the supporting bearing and hence result in vertical poundings between them when they are in contact again. These vertical poundings can significantly alter the seismic responses of the bridge structure and may cause severe damage to the bridge components such as bridge girder, supporting bearing and bridge pier. Neglecting the influence of vertical earthquake loading may lead to inaccurate estimation of seismic responses of bridge structures, especially when they are subjected to near-fault earthquake with relatively large vertical motion.
Publisher: Informa UK Limited
Date: 12-04-2022
Publisher: Springer Science and Business Media LLC
Date: 04-2017
Publisher: Elsevier BV
Date: 05-2022
Publisher: World Scientific Pub Co Pte Lt
Date: 09-2013
DOI: 10.1142/S179343111350019X
Abstract: Seismic induced pounding damage to bridge structures was repeatedly observed in many previous major earthquakes. To avoid this adverse effect, extensive research efforts have been made by many researchers. This paper presents a state-of-the-art review in this field. It includes a brief review of the numerical modeling of bridge structures and impact models, numerical simulation of pounding responses between different components of bridge structures, experimental investigations, and pounding mitigation methods.
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 2022
Start Date: 2015
End Date: 12-2018
Amount: $360,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2021
End Date: 01-2023
Amount: $803,684.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2019
End Date: 12-2023
Amount: $380,000.00
Funder: Australian Research Council
View Funded Activity