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An analytical and experimental investigation on the shear strength of High Performance Concrete (HPC) beams with vertical shear reinforcement or stirrups was carried out. The analytical work involved developing a theory based on the truss analogy, capable of predicting the response and shear strength of such beams subjected to combined bending moment and shear force.The experimental work comprised forty-eight beam specimens in eight series of tests. Most of the beams were 250 mm wide, 350 mm deep and had a clear span of approximately 2 metres. The largest beam was 250 mm wide, 600 mm deep and had a clear span of 3.1 metres. Test parameters included the concrete cover to the shear reinforcement cage, shear reinforcement ratio, longitudinal tensile steel ratio, overall beam depth, shear span-to-depth ratio and concrete compressive strength. The loading configurations included using one, two or four symmetrically placed concentrated loads on simply supported spans.The theory predicted the shear strength of the beams in the present study well. When beams from previous investigations were included, the theory also gave good prediction of the shear strength. Apart from this, comparisons of shear strength were also made with the predictions by the shear design provisions contained in the Australian Standard AS 3600 (1994), American Concrete Institute Building Code ACI 318-95, Eurocode EC2 Part 1 and Canadian Standard CSA A23.3-94. The AS 3600 method was found to give the best correlation with the test results among all the code methods.

Abstract not available

Abstract In order to improve the optimisation of mineral processing operations the rheological properties of slurries must be determined as accurately as possible under the conditions that closely resemble actual site conditions. The rheology of particles suspended in Newtonian fluids is well documented. However, the rheology of particles in non-Newtonian fluids has not been the subject of much investigation till now. The work conducted here attempts to fill this gap in knowledge. The rheological properties of slurries are heavily dependent on the solids concentrations and particle-solid interaction. At low solids concentrations, constant viscosity and Newtonian behaviour is observed, but as solids concentration increases the rheological behaviour becomes increasingly complex and non-Newtonian with viscosity becoming dependent on the shear rate. The nature of the non-Newtonian behaviour depends on the solid concentration, particle shape, particle size, particle size distribution and the suspending liquid rheological properties. The suspension/slurry may develop a yield stress and become time dependent in nature as structures develop within the fluid at higher solids concentrations. This study however, is primarily focused on the measurement of the rheological properties, where it is assumed that the fluid will be fully sheared and that the rheological properties will be unlikely to change with time. Shear thickening behaviour of slurries was the focus of this work. The aim was to investigate the slurry concentration region where shear thickening occurs. The first objective of the project was to develop a fluid analogue which will have similar rheological behaviour to that of concentrated tailings from gold mines so that it can be used as a test material to simulate the flow behaviour of the tailings in a pipe. The second objective of this project was to enable the prediction of flow behaviour in the pipe loop under certain conditions using the fluid analogue for slurry from Sunrise dam. In order to achieve the objectives, experiments were carried out to obtain a fluid analogue of a shear thickening slurry. CSL 500 and SR 200 rheometers were used for the characterisation of different fluid analogues and shear thickening mineral slurries. Malvern Sizer, model: mastersizerX v1.1, was used to obtain particle size distributions. A mini pipe loop system, located in the laboratory of the Rheology and Materials Processing Centre (RMPC) was used to get pipe line flow data for comparison with the rheometer data. A few fluid analogues with different suspending medium and different concentrations of glass spheres was tested before finally using, 48 vol% glass spheres in 1.8 wt% CMC solution as a fluid analogue for the mineral tailings obtained from Sunrise dam, WA. For comparison between the pipe line and rheometer data, all pipe line data (in the form of 8V/D) were converted to rheometer data (in the form of du/dr) using the Robinowitsch-Mooney equation. The above comparison indicated that it is possible to produce fluid analogue to simulate the flow behaviour of Sunrise dam slurry using a shear thinning suspending medium with high concentration of glass particles. Shear thickening flow behaviour was clearly observed in the rheometer while it was less predominant in a pipe line flow.

A nonlinear finite element model was developed to study the behaviour of unstiffened steel plate shear walls. The model was validated using the results from quasi-static and dynamic experimental programs. With the validated finite element model, the performance of 4-storey and 8-storey Type D (ductile) and Type LD (limited-ductility) steel plate shear walls with moment-resisting beam-to-column connections was studied under spectrum-compatible seismic records. A design procedure that aims to achieve optimal seismic behaviour for steel plate shear walls was proposed. The proposed method uses the concepts of indirect capacity design principles of CAN/CSA-S16-01 to identify the infill plates that are likely to yield in the design earthquake. The proposed method was used for the design of two 4-storey and one 8-storey shear walls. Design axial forces and moments in the boundary columns for the shear walls were shown to be in good agreement with nonlinear seismic analysis results. Results also showed that some of the other capacity design methods available generally underestimate the maximum design forces in the columns, while others can be overly conservative. The effect of loading rate on the dynamic behaviour of steel plate shear walls was also investigated, as was the P-Delta effect in terms of its influence on seismic demand in shear and flexure. A shear strength model of the infill plate with circular openings at any location was developed based on a strip model where all the strips with perforations were partially discounted. A design method for steel plate shear walls with perforations was introduced. The method was applied for the design of boundary columns of a 4-storey steel plate shear wall with perforations. The predicted design forces in the columns for the 4-storey perforated shear wall agreed well with the forces obtained from nonlinear seismic analysis. Finally, an improved simple formula for estimating the fundamental period of steel plate shear walls was developed by regression analysis of the period data obtained from frequency analysis of series of steel plate shear walls. In addition, the effectiveness of a shearflexure cantilever formulation for determining fundamental periods and P-Delta effects of steel plate shear walls was studied. / Structural Engineering

This study assesses the suitability of four sectional shear methods for predicting the shear capacity of reinforced concrete members which do not comply with S6-06 Section 14 stirrup spacing and area requirements. The results of the evaluations indicate that the sectional shear provisions in S6-06, AASHTO LRFD-05 and software Response 2000 appropriately account for variations in stirrup spacing and area detailing, and present with good agreement between predicted and tested shear capacities for member with deficient shear reinforcement. However, shear capacities calculated using ACI 318-08 do not agree well with tested capacities for members with less than minimum stirrups. Two modified shear methods are proposed, which revise the diagonal crack spacing and concrete contribution area assumed by S6-06. The modified shear methods improve predictions of shear capacity relative to predictions calculated using S6-06 and eliminate the issue of non-convergent shear capacity predictions which can result from evaluation using S6-06. / Structural Engineering

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

This dissertation describes the development of a new multi-directional direct simple shear testing device, the Texas A&M Multi-directional Direct Simple Shear (TAMU-MDSS), for testing marine soil samples under conditions, which simulate, at the element level, the state of stress acting within a submarine slope under dynamic loading. Prototype testing and an experimental program to characterize the response of marine clays to complex loading conditions are presented. The work is divided into four major components: 1) Equipment Development: Design and construction of a prototype multi-directional direct simple shear testing device (TAMU-MDSS) that addresses the limitations of previous devices. 2) Support systems: selection of control software, development of data acquisition system and design of back pressure systems for direct pore pressure measurements. 3) Prototype Testing: performance of the TAMU MDSS system and testing of strain-control and stress-control capabilities. 4) Experimental Testing: characterize the response of marine clays to monotonic, dynamic and random loads. The two-directional monotonic, cyclic, circular and figure-8 tests demonstrated the undrained shear strength increases with increasing initial shear stress, (i.e, slope), for shearing in the same direction (equivalent to downhill). The strength decreases for shearing in the direction opposite to the initial stress (shearing uphill). The response is as brittle for shearing in the same direction as the shear stress applied during consolidation initial shear stress and ductile for shearing opposite to initial shear stress. These findings have important implications for the stability of the slope, predicting that forces acting downward in the slope direction will need to mobilize less strain to reach peak strength and initiate failure. This information provides insight into the behavior of marine soils under complex loading conditions, and provides high quality laboratory data for use in constitutive and finite element model development for analysis of submarine slopes.

An extensive review was made to study the wake characteristics of a backward-facing step. Experimental and numerical studies of the backward-facing step suggest that the wake of a separated shear layer to be dependent on parameters such as: expansion ratio, aspect ratio, free stream turbulence intensity, boundary layer state and thickness at separation. The individual and combined effects of these parameters on the reattachment length are investigated and discussed in detail in this thesis. A new scaling parameter, sum of step height and boundary layer thickness at separation is proposed, which yields significant collapse of the available data. Based on the literature review, an axisymmetric model is designed for further investigating the dynamics of the flow independent of aforementioned parameters. Additionally, porous suction strips are incorporated to study the step wake characteristics independent of Reynolds number. This model has been built and will be tested extensively at UTIAS.

An extensive review was made to study the wake characteristics of a backward-facing step. Experimental and numerical studies of the backward-facing step suggest that the wake of a separated shear layer to be dependent on parameters such as: expansion ratio, aspect ratio, free stream turbulence intensity, boundary layer state and thickness at separation. The individual and combined effects of these parameters on the reattachment length are investigated and discussed in detail in this thesis. A new scaling parameter, sum of step height and boundary layer thickness at separation is proposed, which yields significant collapse of the available data. Based on the literature review, an axisymmetric model is designed for further investigating the dynamics of the flow independent of aforementioned parameters. Additionally, porous suction strips are incorporated to study the step wake characteristics independent of Reynolds number. This model has been built and will be tested extensively at UTIAS.