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This paper describes and discusses the vibration serviceability of the innovative prestressed cable-reinforced concrete truss (i.e., prestressed cable RC truss, PCT for abbreviation) floor system subjected to heel-drop impact loading, based on the theoretical and experimental studies. In the theoretical analysis, the PCT floor system is idealized as an anisotropic rectangular plate with four built-in edges and the weighted residual method was used. A field test was carried out to investigate the dynamic characteristics of the PCT floor system and to validate and demonstrate the convergence of the theoretical solution. As a result, the experimental results agree well with the theoretical ones. The decrease of vibration is dramatic in the direction perpendicular to the PCT girder and is at a slower rate along the direction of the girder. The investigated PCT floor system has a low fundamental natural frequency (<4 Hz) with low damping ratio (≈2%). According to one standard of vibration criteria, the innovative floor system exhibits satisfactory vibration perceptibility. [ABSTRACT FROM AUTHOR]

The tubed steel-reinforced-concrete (TSRC) column can be interpreted as a special steel-reinforced-concrete (SRC) column where the reinforcement cage is replaced with an outer encased thin-walled steel tube for confining the concrete core. In this study, seven circular TSRC columns using high-strength concrete ( f cu , 150 = 97.6 MPa) were tested under combined constant axial compression and lateral cyclic load. Two primary system parameters, the axial load ratio and the arrangement of shear studs, were considered in this test. The test results indicate that the TSRC specimens exhibit excellent ductility and plastic deformation ability. The deformation of the steel section develops coherently with the high-strength concrete for both the specimens with shear studs on the steel section and those without, due mainly to the confinement from the steel tube. The lateral strength, ductility, and deformability of the circular TSRC specimens are not effectively enhanced by installing shear studs on the steel section. The axial load-moment interaction diagrams of the specimens were developed according to the ACI and EC4 methods. The predictions from the EC4 method appear to better match with the experimental results. [ABSTRACT FROM AUTHOR]

The circular tubed-reinforced concrete (TRC) column is a kind of special concrete-filled steel tube (CFST) columns, in which the outer thin-walled steel tube does not pass through the beam-column joint and thus can avoid the direct transfer of an axial load and maximize the confinement effect from the steel tube. Although the columns possess high load-carrying capacities and good ductility performance in seismic zones, there is a possible decrease in the axial bearing capacity of the TRC column to RC beam connections due to the discontinuity of the column tube, which is a particular concern to engineers. To compensate for the discontinuity of the column tube, strengthening stirrups, a tube with rectangular openings, and horizontal haunches are adopted in the connection zone as Type A, Type B, and Type C connections, respectively. Nine connections aforementioned and four reference circular TRC columns were tested under axial compression. The experimental results show that Type B and Type C connections are effectively strengthened, while Type A connection needs further strengthening because of the lower axial bearing capacity than the reference columns. A finite element (FE) model was developed to simulate the behavior of connections under axial compression. The predicted load-stain curves are in good agreements with the measured ones. A theoretical model for predicting the axial bearing capacities of the connections which is based on the confined concrete theory and local compression theory is proposed. [ABSTRACT FROM AUTHOR]