Parametric investigations on dynamics of cracked thin rectangular plates, excited by a moving mass

To estimate the progressive collapse resistance capacity of a multi-column frame tube structure with an assembled truss beam composite floor (ATBCF), pushdown analysis and nonlinear dynamic analysis are conducted for such a structure using the alternate load path (ALP) method. The bearing capacities of the remaining structures under three different work conditions, which are the side middle column removal, the edge middle column removal, and the corner column removal, are individually studied, and the collapse mechanism of the remaining structures is analyzed based on the aspects of the internal force redistribution and the failure mode of the second defense line. Simultaneously, the influence of the column failure time on the dynamic response of the remaining structure and the dynamic amplification coefficient is discussed. The results indicate that the residual bearing capacity of the remaining structure following the bottom corner column removal is higher than that of the one following the side or edge middle column removal, while the latter has a stronger plastic deformation capacity. When the ALP method is adopted to operate the progressive collapse analysis, it is reasonable to take the column failure time as 0.1 times the period of the first-order vertical vibration mode of the remaining structure, and it is suitable to set the dynamic amplification coefficient as 2.0, which is the ratio of the maximum dynamic displacement to the static displacement of the remaining structure under the transient loading condition.

Section: Discussionmentioning

confidence: 93%

Progressive Collapse Resistance Assessment of a Multi-Column Frame Tube Structure with an Assembled Truss Beam Composite Floor under Different Column Removal Conditions

Zhao,

Chen,

Zhang

et al. 2023

“…Calculating BRILs under vehicle loading necessitates the consideration both of dynamic parameters and the forced motion of the structure [24,25]. This differs from the basic assumptions of ILs in structural mechanics.…”

Section: Experimental Overviewmentioning

confidence: 99%

Research on Bridge Integrity Assessment and Early Warning Monitoring Methods Based on Bearing Reaction Force

Li,

Gan,

Zhao

et al. 2024

Traditional bridge monitoring and damage identification techniques typically rely on full-bridge coverage of sensors, such as displacement or strain sensors. However, this approach proves economically unfeasible for the vast numbers of small- and medium-span continuous beam bridges. In response to the need for rapid damage identification and integrity assessment of continuous beam bridges, a novel bridge safety monitoring method relying solely on bearing reaction forces is proposed. Firstly, the analytical expressions for the bearing reaction influence lines of a three-span continuous beam bridge under damage conditions were derived. Secondly, a rapid structural damage localization method based on the bearing reaction influence lines was proposed. Finally, feasibility and applicability were confirmed through numerical simulations and experimental validation. Additionally, the discussion includes the implementation of the warning classification and threshold setting using data from bearing force monitoring. The research demonstrates that utilizing a limited amount of bearing reaction force information can not only identify damage areas in a “non-full-coverage” manner, but also facilitates early warning and the integrity assessment of bridges. In the future, there is potential for large-scale application in medium- and small-span continuous beam bridges.

“…Shaking table tests can also be performed on the overall structural model using this type of wall panel. Additionally, the theoretical models proposed in references [27][28][29] regarding the behavior of cracked plate-like structures under dynamic loading are helpful for studying the vibration characteristics of structures. We also consider conducting research in this area in the future.…”

Section: Future Workmentioning

confidence: 99%

Experimental Study on Seismic Performance of Prefabricated Monolithic Concrete–Polystyrene Panel Composite Wall Panels

Zhao,

Fan,

Zhang

et al. 2024

A normal composite wall panel is a structural component composed of polystyrene insulation boards and concrete surface layers reinforced with steel wire mesh. It can be entirely prefabricated in a factory or constructed with the concrete surface layers cast on-site. A novel prefabricated monolithic concrete–polystyrene panel composite wall panel (CPC wall panel) is proposed in this study. The CPC panel features a middle part that is prefabricated in the factory while the reinforced concrete regions at its two side ends are cast on-site. To evaluate the seismic performance of the wall panel, 18 CPC specimens were designed, manufactured, and quasi-statically tested, through which the structural behaviors, failure mode, and load-bearing capacity were studied. In addition, the influences of the height-to-width ratio and the vertical compressive stress level on the seismic performance of the CPC panels were also investigated. The test results showed that the connectors spaced at 400 mm × 500 mm could ensure the concrete layers on both sides of the polystyrene board worked collectively under seismic conditions. When subjected to lateral loads, the interface between the newly poured concrete and the existing concrete exhibited good bonding. Moreover, the failure mode of the CPC wall panel was largely correlated to the height-to-width ratio that, for specimens having four steel bars of 12 mm diameter and a height-to-width ratio greater than 1, the flexural failure was initially developed, followed by diagonal shear failure. In specimens with a height-to-width ratio of 1, flexural and diagonal shear failures occurred almost simultaneously. For specimens with a height-to-width ratio of less than 1, the final diagonal shear failure was predominant. The longitudinal reinforcing bars at the two ends of the CPC panels could effectively improve their lateral load-bearing capacity, with the enhancement influenced by the height-to-width ratio, the vertical load applied to the wall panel, and the cross-sectional area of the steel bars. In practice, the lateral load-bearing capacity of the CPC panel can be conservatively evaluated using the calculation method of the reinforced concrete shear walls. Finally, the ductility of the CPC specimens was affected by the height-to-width ratio and the axial compressive stress level, such that the specimens with a larger height-to-width ratio and lower axial compressive stress exhibited better ductility.