Narrow Results

There have been numerous experimental studies on the seismic collapse of reinforced concrete (RC) buildings and RC girder bridges, but not on the seismic collapse of RC pedestrian cable-stayed bridges. Postearthquake field investigations revealed that if RC pedestrian cable-stayed bridges in seismic regions were not appropriately designed, they are likely to encounter severe damage or collapse. This paper thus presents an experimental investigation on a 1:12 scaled RC pedestrian cable-stayed bridge to explore the seismic behavior and collapse mechanism of the bridge under different levels of ground motion. The design, construction, and installation of the bridge, along with the shake table tests, were performed. The dynamic characteristic tests of the bridge were carried out, with the natural periods and mode shapes identified. The bridge was then tested by subjecting it to three levels of ground motion, i.e. small, moderate and large earthquakes. The seismic behavior and seismic-resistant capacity of the cable-stayed bridge were finally assessed at the component level and the failure mode of the bridge was identified based on the seismic responses recorded by the measurement system. The test results showed that the collapse of the RC pedestrian cable-stayed bridge was triggered from the flexure failure of its columns and ended with the flexure-shear failure of its tower.

In this study, the collapse behavior of a family of tensegrity structures, i.e. di-pyramid (DP) barrel-vaults that can offer promising solutions for civil engineering applications is analyzed. Depending on whether struts’ snap or cables’ rupture dictate the occurrence of overall collapse, two different designs are considered. The effects of geometric parameters, self-stress properties, loading type, boundary conditions and strengthening schemes on the structural behavior are discussed. It is found that the structures with symmetric and ridge loading types undergo bifurcation type instability instead of limit point which is encountered in the cases with asymmetric loading type. Constraint against lateral thrust is beneficial in improving strength and initial stiffness of the studied cases, by as much as 60% and 90%, respectively. In most cases, the rate of strength variation associated with increasing self-stress levels is quite slow, while the slackness load increases by at least 400% being the primary achievements. By using non-uniform self-stress distribution, the initial stiffness of these structures can be increased up to 240%. Increasing the rise-to-span ratio improves the initial stiffness and collapse strength of the structure significantly at the expense of expedition of cables slackness. Significant gains in collapse resistance of these structures under symmetric loading are obtained with strengthened critical struts or cables, depending on which collapse case dominates, but the initial stiffness is generally not influenced by these schemes.

Ultra high voltage (UHV) transmission tower-lines systems (TTLSs) are responsible for the crucial function of transmitting and distributing electrical power over long distances, which inevitably traverse active tectonic faults when passing through seismic areas. This paper investigates the seismic behaviors of the fault-crossing UHV TTLSs, taking into account the traveling wave effects of fault-crossing ground motions. Furthermore, three scenarios (i.e. the fault located at the midspan, the side span, and the one side) according to the location of the faults relative to the TTLSs, are designated to investigate the effects of fault-crossing locations on the seismic behaviors of the fault-crossing TTLSs. The results indicate that the traveling wave effects may amplify or weaken the seismic responses and collapse of the near-fault and fault-crossing TTLSs, and the effects on the longitudinal displacement responses of the TTLS are significantly greater than those in the transverse direction, but they do not affect the distribution of the collapse weak position of the TTLSs across the fault. Besides, the effect of traveling waves on the seismic behaviors of the transmission tower further away from the fault is greater than that relatively closer to the fault. This study of the impact of the traveling wave effects and fault-crossing locations on the TTLSs serves as a valuable reference for seismic behaviors of the UHV TTLSs crossing faults.

In this paper, the dynamic compressive response of metal sinusoidal corrugated core sandwich plates is investigated. The analytical model for the reaction forces of top and bottom face sheets subjected to constant velocity are developed. Finite element (FE) method is carried out to predict the dynamic collapse of metal sinusoidal corrugated cores. Several collapse modes of cores are found in terms of different impact velocity and relative core density. The analytical predications are compared with numerical results, and the analytical model captures numerical results for reaction forces reasonably. The collapse mechanism maps are constructed for sinusoidal corrugated cores with elastic-perfectly plastic material and strain hardening plastic material. The effect of strain rate sensitive on the collapse response is discussed. It is demonstrated that the strain hardening of the metal material increases the dominant deformation mode of the collapse mechanism maps.