With a spate of high-profile structural collapses leading to severe casualties and economic loss in recent history, there has been a growing interest in understanding the behavior of building structures in resisting progressive collapse.... more
With a spate of high-profile structural collapses leading to severe casualties and economic loss in recent history, there has been a growing interest in understanding the behavior of building structures in resisting progressive collapse. While many experimental and analytical studies have been conducted, they have mainly been focused on beam-column or beam-column-slab frames. This study, on the other hand, focuses on the behavior of reinforced concrete (RC) flat slab structures, as they are also highly vulnerable to collapse. This is especially so given that: 1) flat slab structures may have insufficient stiffness to redistribute the loads initially resisted by the lost column; and 2) the residual load-resisting capacity of remaining structures may not be able to sustain existing service loads after removal of several columns. Two series of multi-panel RC flat slab substructures were tested with two different loading rigs to study the load redistribution behavior and residual resisting capacities of flat slab structures when two different phases of collapse are concerned. The main test results such as load-displacement response, crack pattern, failure modes, and local strain gauge readings were presented and discussed. Based on test results, a series of further analyses were carried out to elucidate the effects of each design parameter.
Research Interests:
Reported studies have showed that Thrombin Activatable Fibrinolysis Inhibitor (TAFI) may be associated with an increased risk of venous thromboembolism. But the relation of VT with TAFI gene SNPs could not be clearly demonstrated. Thus,... more
Reported studies have showed that Thrombin Activatable Fibrinolysis Inhibitor (TAFI) may be associated with an increased risk of venous thromboembolism. But the relation of VT with TAFI gene SNPs could not be clearly demonstrated. Thus, we conducted a meta-analysis to analyze the associations between three TAFI variants -438G/A, 505G/A and 1040C/T and the risk of venous thrombosis. We carried out a systematic search to obtain all the eligible studies published before 30th October 2014. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were computed to assess the association. 13 eligible studies were enrolled including 2321 patients and 2464 controls. There was a significant association between 505G/A and the risk of VTD under all models except recessive model (G vs. A: OR=1.13, 95% CI: 1.02, 1.26; GG vs. AA:OR=1.47, 95% CI: 1.14, 1.88; GA vs. AA: OR=1.36, 95% CI: 1.06, 1.73; GG+GA vs. AA: OR=1.41, 95% CI: 1.12, 1.77). Similarly, obvious relationship was observed in sub...
Research Interests:
ABSTRACT Gardenia jasminoides Ellis is an evergreen tropical plant and favorite to gardeners throughout the world. Several studies have documented that in vitro micropropagation can be used for clonal propagation of G. jasminoides Ellis,... more
ABSTRACT Gardenia jasminoides Ellis is an evergreen tropical plant and favorite to gardeners throughout the world. Several studies have documented that in vitro micropropagation can be used for clonal propagation of G. jasminoides Ellis, the efficiency remained low. In addition, no information is available on the genetic and epigenetic fidelity of the micropropagated plants. Here, we report on a simplified protocol for high efficient micropropagation of G. jasminoides Ellis cv. “Kinberly” based on enhanced branching of shoot-tips as explants. The protocol consisted of sequential use of three media, namely, bud-induction, elongation and root-induction. By using two molecular markers, amplified fragment length polymorphism (AFLP) and methylation sensitive amplified polymorphism (MSAP), we analyzed the genetic and DNA methylation pattern stability of 23 morphologically normal plants randomly taken from a sub-population (>100) of micropropagated plants originated from a single shoot-tip. We found that of >1,000 scored AFLP bands across the 23 micropropagated plants, no incident of genetic variation was detected. In contrast, of 750 scored MSAP bands, moderate but clear alteration in several DNA methylation patterns occurred in the majority of the 23 micropropagated plants. The changed methylation patterns involved both CG and CHG sites representing either hyper- or hypo-methylation, which occurred without altering the total methylation levels partly due to concomitant hyper- and hypo-methylation alterations. Our results indicated that epigenetic instability in the form of DNA methylation patterns can be susceptible to the in vitro micropropagation process for G. jasminoides Ellis, and needs to be taken into account in the process of large-scale commercial propagation of this plant.
Research Interests:
A series of six one-third scaled reinforced concrete (RC) structural walls with irregular or regular openings were tested to investigate the effects of size, arrangement, and irregularities of the openings on the seismic behaviour of RC... more
A series of six one-third scaled reinforced concrete (RC) structural walls with irregular or regular openings were tested to investigate the effects of size, arrangement, and irregularities of the openings on the seismic behaviour of RC walls. The crack pattern development, failure mechanism, and hysteretic responses of tested specimens are presented. The stiffness deterioration and equivalent hysteretic damping
(energy absorption capacity) of tested specimens are compared and discussed. Another series of six rectangular walls with openings, which are tested by Yanez et al., are also introduced for quantification of the flange effects on seismic behaviour of RC walls with openings. It is found that flanges could significantly increase ultimate strength but reduce deformation capacities. Moreover, flanges may change the
failure mode of rectangular walls from ductile flexural failure to brittle sliding shear failure. Flanges may aggravate the concrete crushing, spalling as well as buckling and fracture of vertical reinforcements. However, concrete crushing and rebar fracture is mainly concentrated in the flanges.
(energy absorption capacity) of tested specimens are compared and discussed. Another series of six rectangular walls with openings, which are tested by Yanez et al., are also introduced for quantification of the flange effects on seismic behaviour of RC walls with openings. It is found that flanges could significantly increase ultimate strength but reduce deformation capacities. Moreover, flanges may change the
failure mode of rectangular walls from ductile flexural failure to brittle sliding shear failure. Flanges may aggravate the concrete crushing, spalling as well as buckling and fracture of vertical reinforcements. However, concrete crushing and rebar fracture is mainly concentrated in the flanges.
Research Interests:
Numerous studies have indicated that the practice of ignoring the contribution of reinforced concrete (RC) slab in resisting progressive collapse is overconservative; however, the extent of influence of a slab, especially in terms of... more
Numerous studies have indicated that the practice of ignoring the contribution of reinforced concrete (RC) slab in resisting
progressive collapse is overconservative; however, the extent of influence of a slab, especially in terms of dynamic responses, have been
rarely studied. To quantify this effect, two series of RC beam–column substructures (named DS and DF in this paper), with and without slab
respectively were subjected to a series of dynamic tests involving the sudden removal of a corner support. To further elucidate the dynamic
response of RC frames against progressive collapse, the experimental data acquired in this study were compared with their respective static
responses derived in a previous series of tests published in another paper. The dynamic effects were evaluated by the newly defined term
dynamic load increase factor (DLIF), which was defined as the ratio of static ultimate strength (SUS) to dynamic ultimate strength (DUS).
The SUS of the test specimens had been captured in their respective static tests; however, the DUS of each specimen could not be determined
based on a single dynamic test. Thus, a single-degree-freedom (SDOF) model was validated and used to conduct incremental dynamic
analyses for each specimen.
progressive collapse is overconservative; however, the extent of influence of a slab, especially in terms of dynamic responses, have been
rarely studied. To quantify this effect, two series of RC beam–column substructures (named DS and DF in this paper), with and without slab
respectively were subjected to a series of dynamic tests involving the sudden removal of a corner support. To further elucidate the dynamic
response of RC frames against progressive collapse, the experimental data acquired in this study were compared with their respective static
responses derived in a previous series of tests published in another paper. The dynamic effects were evaluated by the newly defined term
dynamic load increase factor (DLIF), which was defined as the ratio of static ultimate strength (SUS) to dynamic ultimate strength (DUS).
The SUS of the test specimens had been captured in their respective static tests; however, the DUS of each specimen could not be determined
based on a single dynamic test. Thus, a single-degree-freedom (SDOF) model was validated and used to conduct incremental dynamic
analyses for each specimen.
Research Interests:
The slew of high profile engineering calamities in the past decade has demonstrated the disastrous consequence of progressive collapse. However, the low probability of such events actually occurring means it is uneconomical to spend... more
The slew of high profile engineering calamities in the past decade has demonstrated the disastrous consequence of progressive collapse. However, the low probability of such events actually occurring means it is uneconomical to spend extreme resources to design every building against progressive collapse. A more feasible proposition would be to consider alternative fall-back parameters such as secondary load carrying mechanisms that can help to reduce the severity of the collapse, should it actually occur. However, to date, very limited studies have been carried out to quantify the effectiveness of such secondary load carrying mechanisms in resisting progressive collapse, especially membrane actions developed in RC slabs. Therefore, a series of 6 one-quarter scaled specimens were tested and the failure modes, loaddisplacement relationships, load redistribution responses, and strain gauge results are presented herein. The contribution of each mechanism
on the load-carrying capacity is discussed. A series of analyses are also carried out to better quantify the findings made in the study.
on the load-carrying capacity is discussed. A series of analyses are also carried out to better quantify the findings made in the study.
Research Interests:
Abstract: Unable to generate sufficient ductility and continuity, RC flat slab structures are vulnerable to progressive collapse, in which the relatively brittle failure mechanism attributable to punching shear failure may lead to... more
Abstract: Unable to generate sufficient ductility and continuity, RC flat slab structures are vulnerable to progressive collapse, in which the relatively brittle failure mechanism attributable to punching shear failure may lead to catastrophic consequences. Thus, it is necessary to
evaluate the effectiveness of approaches for improving the ability of flat slabs to mitigate progressive collapse. Previous studies have indicated that integrity reinforcement may enhance the behavior, particularly postpunching behavior, of newly designed flat slab structures. However,
limited tests have been conducted to determine reliable approaches for strengthening existing flat slab structures to resist progressive collapse. In this study, a series of seven multibay flat slab substructures were cast and tested to assess the effectiveness of proposed glass fiberreinforced
polymer (GFRP) strengthening schemes for improving the progressive collapse behavior of existing flat slab structures, owing
to its low density, high strength, rigidity, and excellent resistance to corrosion. Three specimens without strengthening were used as control specimens and the remaining four specimens were strengthened by GFRP strips. Test results indicated that proposed strengthening schemes
effectively improved the initial stiffness and flexural resistance of flat slab structures. However, they did not sufficiently enhance the
postfailure resistance and deformation capacity: there was significant debonding of the GFRP strips from the concrete interface in the large displacement stage, even when specially designed fiber anchors were employe
evaluate the effectiveness of approaches for improving the ability of flat slabs to mitigate progressive collapse. Previous studies have indicated that integrity reinforcement may enhance the behavior, particularly postpunching behavior, of newly designed flat slab structures. However,
limited tests have been conducted to determine reliable approaches for strengthening existing flat slab structures to resist progressive collapse. In this study, a series of seven multibay flat slab substructures were cast and tested to assess the effectiveness of proposed glass fiberreinforced
polymer (GFRP) strengthening schemes for improving the progressive collapse behavior of existing flat slab structures, owing
to its low density, high strength, rigidity, and excellent resistance to corrosion. Three specimens without strengthening were used as control specimens and the remaining four specimens were strengthened by GFRP strips. Test results indicated that proposed strengthening schemes
effectively improved the initial stiffness and flexural resistance of flat slab structures. However, they did not sufficiently enhance the
postfailure resistance and deformation capacity: there was significant debonding of the GFRP strips from the concrete interface in the large displacement stage, even when specially designed fiber anchors were employe
Research Interests:
This paper evaluates the three-dimensional (3D) or slab effects on reinforced concrete (RC) buildings to mitigate progressive collapse, which is caused by the loss of an interior column. Six one-quarter scaled beam–column, or... more
This paper evaluates the three-dimensional (3D) or slab effects on reinforced concrete (RC) buildings to mitigate
progressive collapse, which is caused by the loss of an interior column. Six one-quarter scaled beam–column, or
beam–column–slab substructures are tested. These six specimens are categorised into three series (P-, T- and S-series).
The test results confirm that transverse beams and RC slabs can reduce the collapse vulnerability of RC buildings
effectively. In addition, it is quantified that 3D effects without slab can increase the yield load of the frame by up to
100%, while 3D effects including slab can increase the yield load up by 246.2%. This is because the slabs not only
increase the bending moment capacity of beam sections working as flanges, but also provide more alternative load
paths for load redistribution. RC slab can upgrade the first peak load of the buildings by developing compressive
membrane actions, and upgrade the ultimate load capacity of the building during the large deformation stage by
developing a tensile membrane action. As the number of tested specimens is relatively small, a series of numerical
and parametric studies are carried out to further quantify the 3D or slab effects on RC buildings in resisting
progressive collapse.
progressive collapse, which is caused by the loss of an interior column. Six one-quarter scaled beam–column, or
beam–column–slab substructures are tested. These six specimens are categorised into three series (P-, T- and S-series).
The test results confirm that transverse beams and RC slabs can reduce the collapse vulnerability of RC buildings
effectively. In addition, it is quantified that 3D effects without slab can increase the yield load of the frame by up to
100%, while 3D effects including slab can increase the yield load up by 246.2%. This is because the slabs not only
increase the bending moment capacity of beam sections working as flanges, but also provide more alternative load
paths for load redistribution. RC slab can upgrade the first peak load of the buildings by developing compressive
membrane actions, and upgrade the ultimate load capacity of the building during the large deformation stage by
developing a tensile membrane action. As the number of tested specimens is relatively small, a series of numerical
and parametric studies are carried out to further quantify the 3D or slab effects on RC buildings in resisting
progressive collapse.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Six one-third scale reinforced concrete (RC) beam-column substructures, each with different design detail, span length and span aspect ratio, were designed and tested to investigate the dynamic load redistribution performance of RC... more
Six one-third scale reinforced concrete (RC) beam-column substructures, each with different design detail, span length and span aspect ratio, were designed and tested to investigate the dynamic load redistribution performance of RC substructures following predefined initial damage. The initial damage was caused by the sudden removal of the corner support. The tested variables include: the longitudinal and transverse reinforcement ratio in the beams, columns and joints, design span length and span aspect ratio. Extensive instrumentation was installed in predetermined locations on the tested specimens prior to conducting the tests, recording data such as acceleration, velocity and displacement distribution. The histories of the bending moments, as well as the vertical and horizontal reaction forces at the fixed supports were also noted. The test results indicated that the column removal apparatus was effective and confirmed that the design span length significantly affected the capability of the frames to resist progressive collapse. Furthermore, it was demonstrated that seismically detailed specimens could mount a more robust performance in resisting progressive collapse.► Investigation of dynamic performance of RC substructures after predefined damage. ► Variables include reinforcement ratio and span aspect ratio. ► Design span length affects capability to resist progressive collapse.
Research Interests:
Aer incidents such as the collapse of the Twin Towers which was caused by hijacked aircras crashing into them, collapse of building World Trade Center due to re, and blast induced partial collapse of the Alfred P. Murrah Federal Building... more
Aer incidents such as the collapse of the Twin Towers which was caused by hijacked aircras crashing into them, collapse of building World Trade Center due to re, and blast induced partial collapse of the Alfred P. Murrah Federal Building in Oklahoma City, designing a structure under extreme loading conditions such as blast, re, and hurricanes became an important task for civil engineers. ey need to provide cost eecient design to minimize injuries and improve the probability of survival of people. is is based on the clear understanding of behaviour of the structures, accurate analysis theory and method, eeective numerical modelling soware, and speciic design methods. However, due to the unconventional features of these extreme loading conditions, the behaviour of the structures has not been well investigated; advanced analysis theories including the uid and structure interaction, high strain rate, nonlinear inelastic material behaviour, low-cycle fatigue performance, and failure criterion need to be further developed. Improvement in the performance based design guidance also needs to be made. In addition, the vulnerability assessment and risk assessment of the structures under certain extreme events should also be incorporated into the design practice. is special issue is intended to present and discuss latest research outcome on both experimental and numerical studies. It is also aimed at providing an overview of current trends and advancements in design and analysis of civil engineering buildings and infrastructures. We solicit high quality, original research articles as well as review articles. Potential topics include, but are not limited to: Numerical study of structural members or structural system under blast loading, re, or severe earthquakes Behaviour of tall buildings under strong wind loading such as hurricanes Behaviour of suspension bridges under strong wind loading Advanced numerical simulation of wind structure interactions reat and vulnerability assessment of structures under extreme loading Risk assessment of structures under extreme loading Review/assessment of existing design tools and simpliied methods Authors can submit their manuscripts via the Manuscript Tracking System at