Analysis of elastic systems with discontinuous parameters
Constructions in the form of rectangular planar plates and shallow shells reinforced by a cross system of ribs of great rigidity and loaded with an arbitrary lateral load are considered. The stress-strain state of such structures is described by technical theories of plates and shallow shells. The effect of the stiffeners is taken into account in the equations as additional terms containing factors with the Dirac δ-function and its derivatives. The plate and the shell may have a stepwise variable thickness. The ribs are arbitrary thin-walled beams of variable cross-section that play an essential role in providing the load-carrying capacity of the structure as a whole. The stress-strain state of not only the plate and the shell but also the stiffeners themselves is determined. The questions of the rate of convergence of solutions in the form of trigonometric series describing the stress-strain state in the stiffeners are discussed. The results of analyses of reinforced plates are presented.
Calculation of the ribbed plate in the mixed form “deflection - function of efforts”
Analytical solution of a boundary-value problem for a system of differential equations of deformation is obtained for the rectangular plate supported with ribs of rigidity in the “function of deflection - function of efforts” mixed form. The solution is presented in the form of a series over combinations of regular and special discontinuous functions. The solution leads to fast converging series. A simple algorithm for computations is provided.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.