The main objective of this study was to determine whether Limit Design could be applied to low-rise unbraced concrete frames. The investigation was carried out both analytically and experimentally. In the analytical part, two mathematical models were used to determine the behavior of unbraced frames. The first method used a nonlinear computer program, which takes into account the material and geometric nonlinearities of concrete frames. Several cases of frames with different reinforcement ratios and under different beam to column load ratios were investigated. For each frame the gravity loads were increased proportionately to 3/4 of the ultimate frame capacity. Then, lateral load was applied to failure while keeping the beam and column loads constant. The second mathematical model solved for the frame stability equation by assuming elasto-plastic moment curvature relationships for members. Also, the stability solution was carried out by reducing the frame to a column attached to a linear spring. In the experimental part, two frames were designed for the same loading conditions but by two different methods; and were tested to failure. Frame USD-1 was designed by the Ultimate Strength Design, while Frame LD-1 by a Limit Design method. The columns were 21-in high while the beam was 84-in long. The loading procedure consisted of proportionately loading the beam and columns up to the design load, and then applying the lateral load to failure. The computer study and the stability model solution showed that frames subjected to low column thrusts remained in stable equilibrium until two plastic hinges form, thus constituting a mechanism. The two experimental frames remained in stable equilibrium until two plastic hinges formed in the beams. The ultimate lateral loads of Frames USD-1 and LD-1 exceeded the design lateral load by 66% and 33%, respectively. Based on this investigation, it appears that Limit Design may be used for low-rise unbraced reinforced concrete structures.

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Includes corrigenda inside back cover. / Bibliography: leaves 310-332. / xx, 332 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 1994

Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 2002. / Includes corrigenda (inserted at front) and list of publications published as a result of this research. Includes bibliographical references (leaves 192-199).

Microreproduction of original thesis. / Thesis (PhD)--Stellenbosch University, 1990. / Some digitised pages may appear illegible due to the condition of the original microfiche copy. / ENGLISH ABSTRACT: see item for full text / AFRIKAANSE OPSOMMING: sien item vir volteks.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Four full-size statically indeterminate reinforced concrete frames with two symmetrical bays were tested to obtain sufficient data to evaluate the adequacy of the current ACI-ASCE Committee 352 design recommendations, as well as to determine whether a relaxation of some of the limits in these guidelines can be justified. Each specimen contained three 8.5-foot-long columns, connected at mid-height by two 9-foot-long beams. Initially, a constant axial load was applied to each column. The specimens were then subjected to a displacement-controlled loading schedule to simulate the type of displacements a frame may experience during a severe earthquake. In designing the specimens, the latest recommendations of the ACI-ASCE Committee 352 and the ACI building code ACI 318-83 were satisfied except for the following modifications: (1) the flexural strength ratio (M(R)) in the second specimen was reduced from 1.4 to 1.2, (2) the shear-stress factors (γ) in the joints of the third specimen were increased from 12 and 15 to 15 and 20 for the exterior and interior joints respectively, and (3) the number of the transverse reinforcements inside the right exterior joint in the fourth specimen was reduced from 4 to 2 sets of hoops. The conclusion inferred from the results indicate that for drift levels within the elastic range, the elongations and the rotations of the beam regions near the faces of the columns, in addition to the joint shear strains, were not affected by the design values for the primary variables in the last three specimens. For larger excursions into the inelastic range, the relaxation of the current Committee 352 design recommendations in the last three specimens not only showed a significant effect in reducing the elongations and the rotations of the beams, or in increasing the joint shear strains but led to lower energy dissipation of the specimens. Consequently, the current design guidelines by the ACI-ASCE Committee 352 yield statically indeterminate frames which exhibit sufficient ductility.

This manuscript predicts the behavior of a doubly reinforced concrete beam with a circular opening at its midspan by closely analyzing traditional beam theory and design. It then confirms these predictions with finite element modeling software while providing design suggestions. The analysis is limited to the tensile and compressive stresses and cracking behavior. The objectives are to determine the stress distribution around a circular opening that agrees with conventional beam theory. The beam behavior is examined from zero load to failure load. ANSYS is utilized in lieu of real world testing, and the appendix includes the finite element results for a beam including design recommendations. The results lay the foundation for a possible new design procedure of concrete beams with single or multiple circular openings. This research offers useful information that was unavailable previously. More research can be conducted to help designers to design lighter, more efficient concrete beams. / by Heather R. Anesta. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

A cyclic polarization procedure was designed to evaluate the pitting potentials of high performance stainless steels in synthetic concrete pore water at different chloride concentrations. Cyclic polarization scans were performed on high performance stainless steel reinforcements, S32201, S32305 and S32205. Pitting initiation was observed below the oxygen evolution potential for high chloride concentrations. S32201 and S32304 showed the presence of metastable pitting before reaching its pitting potential. Pitting resistance performance, based on cyclic polarization, was consistent with each material's respective Pitting Resistance Equivalent Number (PREN) value. For S32201 and S32304, pitting potential decreased as the chloride concentration increased, whereas S32205 did not pit at the chloride concentrations tested. / by Erika Maria Sanchez. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

Thesis. 1978. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / by George Szepesi. / M.Arch.A.S.