Engineering Commons^™

Density Currents In Circular Wastewater Treatment Tanks, David M. Laliberte

Dissertations and Theses

Deviations from ideal flow and settling occur in circular wastewater treatment tanks because of tank geometry, flow conditions, and density currents caused by variations in suspended solids concentration and temperature distributions. Thermally induced density currents were investigated in this study. Under winter, low flow conditions, measurements were made of vertical and radial temperature distributions in the circular chlorination tank at Lake Oswego, Or., and in the circular primary and secondary clarifiers at Bend, Or. Thermistor arrays were used to collect the data which exhibited both vertically well-mixed and a two-layer flow regime. Inlet geometry and suspended solids in the secondary …

Investigation Of Mixed-Made Fracture In Concrete, Stylianos C. Aniftos

Theses

This study is aimed at evaluating the failure characteristics of concrete in the notched beam configuration. In general, for Mode I failure tension is commonly encountered. However, in the area of high shear stress, it remains to be a question whether shear or Mode II failure exists. Researches carried out in the past decade confirmed the existance of both Mode I and Mode II failure. It is the objective of this investigation to clarify this failure characteristics using FRANC an interactive fracture mechanics software.

The investigation carried out in this study used the experimental results of Bazant and Pfeiffer (3) …

Construction Cost Estimating In Project Management, Kalpit N. Patel

Theses

The primary objective of Cost Estimating is to support the timely generation of bid or alternative estimates. Cost Estimating also supports management analysis of estimate accuracy, reasonableness and project risk through the generation of summary reports and analysis. Estimates also provide a base of information during construction for such items as scope changes to the contract, variations in costs of the project cost, total project cost, feedback for scheduling etc.

Contruction cost estimating is the process of identifying and compiling the many items of cost that will enter into a construction project. This is a procedure that requires very detailed …

Experimental Evaluation Of Process Zone Deformation In Concrete, Cherng-Maou Meng

Theses

Concrete structures are often subjected to a variety of loading conditions. Under ultimate load design, concrete structures can resist these loads without evident deformation. However, under service, tension cracks will develop and depending on their location, they may impair load carrying capacity.

It is generally believed that microcrack development is preceeded by formation of a relatively long microcracked region. A large number of studies have indicated that due to formation of this process zone (microcracked zone), Linear Elastic Fracture Mechanics (LEFM) principles are not applicable to concrete. However, a number of nonlinear models can be developed if the length of …

The Frontal Method For Finite Element Analysis On Ibm-3090 Vector Computer, Chaerul Kamal

Civil & Environmental Engineering Theses & Dissertations

In this report, a Finite Element program based on the Frontal method was implemented on the IBM-3090 to exploit the vector capabilities offered by modern high performance vector computers. The overall computational speed for the Frontal Finite Element program was increased by 30% when the vector instructions were introduced. The Frontal solution for a system of simultaneous linear equations, however, has shown only minor improvement when vector instructions were used. More improvement in computational speed and memory storage can be expected by using the Parallel Frontal method with Substructures.

Nonproportionally Loaded Steel Beam-Columns And Flexibly-Connected Nonsway Frames, Siva Prasad Darbhamulla

Civil & Environmental Engineering Theses & Dissertations

A theoretical study of the inelastic stability of nonproportionally loaded steel beam-columns and flexibly-connected frames is conducted. Specifically, solution techniques are formulated to predict the nonlinear behavior of cross sections, spatial beam-columns, and nonsway plane frames under the combined influence of imperfections, flexible connections, and nonproportional loads. A set of new inelastic slope-deflection equations for imperfect members are derived and their use illustrated through in-depth studies of flexibly-connected portal and two-bay two-story frames. These equations are derived from a system of nonlinear ordinary differential equations. The member studies are carried out using a second-order finite-difference solution to a set of …