This thesis investigates the effects of elastic restraint at the supports on the behaviour of shallow concrete arches, and the time-dependent effects of shrinkage and creep of concrete on the nonlinear behaviour of shallow arches. The nonlinear behaviour of shallow circular arches with elastic rotational restraints at each support and subjected to a uniformly distributed radial load is firstly investigated. A virtual work formulation is used to establish both the nonlinear equilibrium equations and the buckling equilibrium equation for shallow arches. The analytical results show that the effects of the stiffness of the rotational restraints on the prebuckling and buckling response are significant. An analytical model is developed for the in-plane elastic stability analysis of shallow parabolic arches with horizontal spring supports subjected to a uniformly distributed vertical load. A parametric study is undertaken using the proposed analytical model. It is found that the effects of the stiffness of the horizontal springs on the prebuckling response, buckling load and buckling behaviour of arches are significant. An analytical model is developed to simulate the time-dependent behaviour of shallow concrete parabolic arches with horizontal spring supports subjected to a sustained loading, and in particular to investigate creep buckling. The time-dependent buckling load and the critical time (or age) of the arches are calculated by using an iterative process based on the proposed model. A systematic parametric study is undertaken, and the results show that the various parameters have a profound effect on the time-dependent buckling load and the prebuckling life of arches. Both short-term and long-term experimental investigations of shallow parabolic tied concrete arches are described and used to validate the analytical models. For the short-term tests, three concrete arches were subjected to a uniformly distributed vertical load and were loaded to failure. For the long-term tests, seven concrete arches were subjected to sustained service loads. The instantaneous and time-dependent deflections were recorded throughout the period of loading, together with the distribution of the horizontal thrust at the supports. Comparisons between the experimental results and the analytical predictions using the analytical models are made to verify the accuracy of the theoretical models.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains x, 147 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 117-121).

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 65-66).

Thesis (Ph.D.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 171-177.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 108-112.

Thesis (M.S.)--University of Nevada, Reno, 2006. / "December, 2006." Includes bibliographical references (leaves 82-85). Online version available on the World Wide Web.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 107-109).

Master of Science

A postbuckling analysis procedure for simply-supported, symmetrically laminated, rectangular, generally orthotropic plates under uniaxial compression based on a Marguerre-type energy method was developed. The analysis assumes the out-of-plane displacement to be represented by using a truncated Fourier sine series. The unknown coefficients of the displacement function were obtained from a system of nonlinear algebraic equations by using the principle of minimum potential energy. The number of terms that are to be retained in the out-of-plane displacement function to obtain an accurate response was studied and identified for a wide range of generally orthotropic plates. In the postbuckling load range, plates are also allowed to change their buckled form. The magnitudes of the total potential energy for possible different deformed shapes of a plate were compared to determine the actual deformed shape. The effect of bending-twisting coupling terms on the postbuckling behavior of anisotropic laminates was also investigated. Several postbuckling problems for isotropic, orthotropic, and anisotropic plates were considered and the results obtained by the present approach were compared with available literature results and finite element solutions to demonstrate the present analysis procedure. The analysis procedure developed was, then, applied to minimum-weight design of laminated plates for postbuckling performance. Laminate failure load used in the postbuckling regime was calculated based on a maximum strain failure criterion. The failure criterion was demonstrated to predict the failure load reasonably well when compared with available test results. Weight comparison between the plates designed against buckling and the ones designed for the postbuckling strength was made to quantitatively evaluate the weight savings achieved for plates that are allowed to buckle. The design variables were assumed to be the layer thicknesses with specified fiber orientations and assumed to take only discrete values. A simple approach based on the penalty method was proposed to achieve the discrete-valued designs. In addition to the regular penalty terms for constraint violation, the proposed approach introduces penalty terms to reflect the requirement that the design variables take discrete values. A variable magnitude penalty term in the form of a sine function was implemented with the extended interior penalty method of the optimization package NEWSUMT-A. The proposed discrete optimization technique was applied to the classical truss and laminated composite plate design problems to demonstrate the performance of the procedure. / Ph. D.

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 1992. / This thesis presents the results of theoretical and experimental investigations into the behaviour and ultimate load capacity of latticed lower panels with cross-bracing diagonals made of equal-leg, hot-rolled steel angles under the effects of in-plane loads. Loading tests to collapse are carried out on cross-bracings in reduced-scale two-dimensional frames of various arrangements. The Southwell-plot of deflection measurements immediately prior to first yield of the diagonals is used to define equivalent end eccentricities and effective length factors, which therefore account for geometric and material imperfections of the test specimens. A proposal for new design formulae for calculating the resistance of struts is presented. The new design equations are based on the secant formula and are calibrs"ed against the experimental results. A computer model is developed based on flexibility equations which do not require an narative analysis procedure. The non-linear effects are given through the inclusion of Berry stability functions. The effects of eccentric forces and nodal restraints are simulated at all joints in which diagonals and main chords are connected . An additional model is formulated using a mainframe finite-element cod, demonstrating that it is now possible to perform non-linear analyses of complex frames including asymmetric members. Experimental results from this and other investigations are compared with ultimate load predictions based on the new design equations and the computer models and also usual buckling curves for design of steel transmission towers. In all cases the proposed models give acceptable predictions ot the behaviour and ultimate capacity of the bracings. In particular, failure loads calculated with the new design equations show improvements with respect to predictions based on current design buckling curves. These equations, therefore, can be used for design of steel latticed tower structures with angle members.