Thesis. 1977. M.Arch.A.S.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography : p. 177. / M.Arch.A.S.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Nov. 13, 2009). Includes bibliographical references (p. 47).

Typescript, etc. / Digitized by Kansas Correctional Industries

The primary objective of the dissertation work is to examine the capacity of precast concrete diaphragms. This work is part of a multi-university research effort to develop a new seismic design methodology for precast/prestressed concrete floor diaphragms. To accomplish this, two-dimensional finite element (FE) models of precast floor diaphragms are created, including new elements to match the response of reinforcing details under combined forces. Using these models, nonlinear static "pushover" analyses are performed by applying body forces in the plane of the floor.The analyses are composed of three major parts:(1) Parametric studies to determine the required diaphragm shear strength relative to design (flexural) strength, termed "shear reinforcement overstrength", to promote a ductile mechanism in precast diaphragms. The performance of precast diaphragms with different shear reinforcement overstrength is examined. Appropriate shear reinforcement overstrength design factors are proposed to produce certain performance targets, in terms of a number of key parameters related to diaphragm geometry and the properties of the diaphragm reinforcing details.(2) Parametric studies to examine the effects of "secondary" diaphragm elements (spandrels, internal beams) on precast diaphragm behavior. Though not directly counted in design to participate diaphragm action, the secondary elements and their connections to the main diaphragm may modify the strength, stiffness and deformation capacity of the diaphragm. Analytical studies are performed to examine their effect on the global characteristics and local demands of precast floor diaphragms. The parameters evaluated include the characteristics of the connection details, the seismic hazard level used in design, diaphragm geometry, and layouts of spandrels and internal beams.(3) Development of a rational method for calculating the service stiffness and yield strength of precast concrete diaphragms. The method involves input of diaphragm geometry and reinforcing details. The method is verified analytically through comparisons to a set of FE analyses for an idealized diaphragm representation (regular single span diaphragm idealized with simple end supports). The method verified for a single set of diaphragm reinforcement details is used to estimate the properties over a range of untopped and topped diaphragm systems. Consideration of spandrel and internal beams in the method is discussed.

This investigation was part of a greater research initiative regarding the seismic vulnerability of precast hollowcore floor systems. The primary focus throughout the research programme has been to investigate the susceptibility to loss of vertical support of the floor system, from the seating beam. Previous research firstly focussed on identifying and understanding preconceived deficiencies with existing seating connection details. This was followed by the validation of amended, superior performing, 'new' seating connection details. However, little consideration has been given to retrofit techniques for already existing buildings, with potentially poor performing existing seating connections. A two-dimensional, single hollowcore unit, seating connection sub-assembly is used to experimentally investigate the seismic behaviour of previously un-tested existing seating connections pre- and post-retrofit. Three existing seating connection configurations, with the hollowcore unit seated directly on the bare concrete seating ledge and with varying seating lengths were tested. These tests were followed by a fourth retrofitted specimen. Both relative rotation between the hollowcore unit and seating beam, and beam elongation 'pull-off' deformations (resulting from the supporting frame deformations) were imposed on the test specimens. In conjunction with this experimental investigation and with prior knowledge from previous investigations, three primary failure mechanisms for existing hollowcore seating connections are summarised. A suite of conceptual retrofit techniques which target the critical structural weaknesses attributed to causing the primary failure mechanisms are outlined. In general, unfavourable performance was exhibited by the existing seating connections in the experimental investigation, resulting in loss of vertical support of the hollowcore unit under imposed 'pull-off' effects. In contrast, when the retrofit strategy was implemented, a higher level of seismic performance, leading to collapse prevention was achieved. A review is carried out into existing beam elongation numerical models, which are simple and involve only hand-type calculation procedures. The aim of this was to investigate potential methods for predicting the 'pull-off' effects on suspended floor systems. From this, a modification is made to an existing, loading dependent method developed by Matthews (2004). The modified method aimed to more accurately represent the loading dependant nature of beam elongation (and the resulting 'pull-off' effects) as described by Lee and Watanabe (2003). A number of beam elongation predictions for a suite of experimental beam elongation data sets were carried out with the modified method. Good agreement was generally seen, both in terms of prediction of the magnitude of elongation and the shape of the elongation profile.

The research on headed stud connections described in this dissertation forms a part of an overall objective of predicting the behaviour of precast concrete panel buildings under earthquake loads. Existing laboratory test data and current design procedures of headed stud connections are briefly reviewed. It is postulated that shear loads are transmitted via a connection to the surrounding concrete by three distinct mechanisms: 1. friction between faceplate and concrete 2. bearing of end of faceplate on concrete 3. interaction between studs and concrete Tests on laboratory models designed to isolate individual aspects of these mechanisms confirm that all three exist. Friction forces between faceplate and concrete are small in comparison with the remaining forces acting in a connection, particularly under cycled loading. Bearing of the end of the faceplate on concrete and interaction between studs and surrounding concrete are shown to be the main contributions to the total load carried by a connection. A simple analytical model is presented for the prediction of the ultimate shear load capacity of a connection and a computer algorithm is proposed for the prediction of the load versus deflection behaviour of a connection under both monotonic and cyclic conditions. Existence of the three mechanisms whereby a connection transfers applied shear forces to the surrounding concrete contradicts the shear friction equation which is currently used in the design of connections. The analytical equations developed in the investigation indicate that the strength of a connection is directly dependent upon the strength of the surrounding concrete, as opposed to the expression for shear friction, which does not contain concrete strength as a variable. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

With the increase in the number of functions in the modern age, it has become quite a challenge for an architect to satisfy the requirements and still have an appropriate architectural expression for the materials and the underlying structure. Such challenges may be found both in nature and man made machines, giving rise to elements with multiple functions. This thesis attempts to explore such precedents offered in both architecture and other areas, and apply the ideas and principles in the design of a primary school. / Master of Architecture

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1963. / MIT Institute Arcives copy has the appropriate accompanying leaves of plates after each title; MIT Rotch Library copy has them all lumped-together at the end. / Three individual titles bound together with a collective title and an introduction. Compiled, with an introduction, by Prof. Eduardo F. Catalano. / Preface: By presenting the three individual theses with a common analysis of material pertinent to the design of each thesis it is hoped that a more rich and extensive result has been attained. / Brunken, Alan Wayne. A multistory precast concrete office building (1963) -- Henney, Thomas. A precast concrete high-rise office building (1963) -- Westbury, Rodney Ames. A multi-story precast concrete office building (1963). / M.Arch.

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