This study concerns the strength and behaviour of low-rise shear walls made from high-strength concrete under reversed cyclic loading. The response of such walls is often strongly governed by the shear effects leading to the shear induced or brittle failure. The brittle nature of high-strength concrete poses further difficulties in obtaining ductile response from shear walls. An experimental program consisting of six high-strength concrete shear walls was carried out. Specimens were tested under inplane axial load and reversed cyclic displacements with the test parameters investigated being longitudinal reinforcement ratio, transverse reinforcement ratio and axial load. Lateral loads, lateral displacements and the strains of reinforcement in edge elements and web wall were measured. The test results showed the presence of axial load has a significant effect on the strength and ductility of the shear walls. The axially loaded wall specimens exhibited a brittle behaviour regardless of reinforcement ratio whereas the specimen with no axial load had a lower strength but higher ductility. It was also found that an increase in the longitudinal reinforcement ratio gave an increase in the failure load while an increase in the transverse reinforcement ratio had no significant effect on the strength but influenced the failure mode. A non-linear finite element program based on the crack membrane model and using smeared-fixed crack approach was developed with a new aggregate interlock model incorporated into the finite element procedure. The finite element model was corroborated by experimental results of shear panels and walls. The finite element analysis of shear wall specimens indicated that while strengths can be predicted reasonably, the stiffness of edge elements has a significant effect on the deformational results for two-dimensional analyses. Therefore, to capture the deformation of walls accurately, three-dimensional finite element analyses are required. The shear wall design provisions given in the current Australian Standard and the Building Code of American Concrete Institute were compared with the experimental results. The comparison showed that the calculated strengths based on the codes are considerably conservative, specially when there exists the axial load.

This study concerns the strength and behaviour of low-rise shear walls made from high-strength concrete under reversed cyclic loading. The response of such walls is often strongly governed by the shear effects leading to the shear induced or brittle failure. The brittle nature of high-strength concrete poses further difficulties in obtaining ductile response from shear walls. An experimental program consisting of six high-strength concrete shear walls was carried out. Specimens were tested under inplane axial load and reversed cyclic displacements with the test parameters investigated being longitudinal reinforcement ratio, transverse reinforcement ratio and axial load. Lateral loads, lateral displacements and the strains of reinforcement in edge elements and web wall were measured. The test results showed the presence of axial load has a significant effect on the strength and ductility of the shear walls. The axially loaded wall specimens exhibited a brittle behaviour regardless of reinforcement ratio whereas the specimen with no axial load had a lower strength but higher ductility. It was also found that an increase in the longitudinal reinforcement ratio gave an increase in the failure load while an increase in the transverse reinforcement ratio had no significant effect on the strength but influenced the failure mode. A non-linear finite element program based on the crack membrane model and using smeared-fixed crack approach was developed with a new aggregate interlock model incorporated into the finite element procedure. The finite element model was corroborated by experimental results of shear panels and walls. The finite element analysis of shear wall specimens indicated that while strengths can be predicted reasonably, the stiffness of edge elements has a significant effect on the deformational results for two-dimensional analyses. Therefore, to capture the deformation of walls accurately, three-dimensional finite element analyses are required. The shear wall design provisions given in the current Australian Standard and the Building Code of American Concrete Institute were compared with the experimental results. The comparison showed that the calculated strengths based on the codes are considerably conservative, specially when there exists the axial load.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [268]-284).

Thesis (M.Sc.(Eng.))--University of Hong Kong, 1968. / Also available in print.

Thesis (Ph. D.)--Lehigh University, 2004. / Includes vita. Includes bibliographical references (leaves R1-R7).

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.L.A.)--University of Hong Kong, 2005. / Includes special report study entitled: Conservation and treatment to cultural landscape.

The object of this thesis is twinfold. Firstly, to study and check the effective width requirements recommended by different committees¹ for the design of ribbed precast concrete load bearing walls. Secondly, to rationalize the practice of the designing of the precast prefabricated components of any general polygonal shape. The recommendations regarding the minimum thickness of a thin wall, the effective width, etc., have been specified for some cases in code books and other tentative specification books², in the form of rules of thumb. In these rules of thumb, several parameters which may be of significance, such as dimensions of the rib itself, are not taken into account. A finite element approach has been adopted to investigate various combinations of these parameters, as well as the effects of different boundary conditions. Similar problems arise also in the cases of T-beams, L-beams and design of aircraft structures, in which a stressed skin is mounted on ribs, which are assembled in the form of a space frame. So far interaction curves have been made available in some design books only for the prestressed concrete member having rectangular cross-sections and for any other shape, approximations are made, such as making a rectangular section having an equivalent area or having the same moment of inertia or section modulii, etc. But this practice seems very irrational especially in the case of precast components which are always produced in a factory on a mass scale. A computer program has been written which can give the interaction curve for the member of any polygonal shape. 1. DRAFT 3: Of PCI Committee, 'Recommendations for Prestressed Bearing Wall Design.' 2. 'Symposium on Precast Concrete Wall Panels.' Publications ACI, SP-11, Second Printing 1966, pp. 39-44. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

A solution to the current problem of wind tunnel wall interference could be achieved by ventilating the test section and thereby controlling the flow pattern around the model. The motivation for the slotted wall test section arises from the fact that a fully open jet and a fully closed jet introduce corrections of opposite sign to the wind tunnel data. This current work is limited to axisymmetric wind tunnels and solid blockage corrections. Such a tolerant axisymmetric wind tunnel (TAWT), which does not need any correction to the measured flow quantities and which is also independent of the test model shape and size would find wide application in the field of industrial aerodynamics. A numerical model based on a surface singularity potential flow method showed that at 70% OAR (open area ratio) for models of size up to 25% blockage and for three different shapes the tunnel design would yield results (coefficient of pressure) with less than 2% error while such models might need up to 75% data correction if tested in a solid wall wind tunnel. Experiments indicated good agreement with the numerical investigation and at 60% OAR the TAWT gave results close to free air results for all the models tested (up to 25% blockage). / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Centrifuge modeling technique is widely used in geotechnical research. Due to the complexity of geosynthetic-reinforced soil retaining walls (GRS-RWs), the centrifuge models of such walls are typically constructed in one stage, where the model is prepared to full height under 1-g and then spun in a centrifuge to the desired g-level or till failure. However, for a retaining wall built in the field, the placement of new soil layer and compaction induces deformations on the previously constructed soil layers, and the wall facing is aligned according to the design at each construction stage. The different construction sequences will lead to differences in the wall performance, including the stress mobilized in the geosynthetic layers. In this study, a multi-stage constructed centrifuge modeling technique was proposed to simulate the construction sequence in the field. The wall facing deformation, tensile force in the geosynthetic layers, and lateral earth pressure behind the wall facing were measured and compared with the traditional one-staged centrifuge model. The results were verified with actual field measurements. The results obtained from multi-staged construction compared favorably to the field measurements. In addition to the construction sequence, the backfill close to the wall facing is usually not as well compacted in the field. The effects of such loose front backfill were also studied by a series of centrifuge models of reinforced soil retaining walls. In addition to the centrifuge modeling of the reinforced soil retaining walls, two series of finite element models were conducted to further study the wall performance. The first series of numerical models included a unified sand model, which was implemented into Abaqus to simulate the backfill. The sand model was firstly calibrated based on the triaxial test results; then, it was used to simulate the wall performance under gravity and dynamic loading. An additional series of FE models were constructed in OptumG2, a 2D finite element geotechnical software to numerically study the influence of loose front and construction sequence of the concrete block reinforced soil retaining walls. Based on the results of centrifuge modeling, simulation of the construction sequence is necessary to obtain a satisfactory assessment of GRS-RWs performance. In this study, the models prepared with multi-staged construction techniques showed better agreement with the field measurements than the models prepared with one-staged construction. In addition, the models with reinforcement simulating the stiffness of the prototype geogrid showed better agreement with field measurements than the models with reinforcement simulating the strength of the prototype geogrid. Besides, a loose front probably existed in the concrete block walls during the field construction based on the comparison of the test results and field measurements. Conclusions from the centrifuge modeling studies were verified by FEM analysis. The dynamic simulation results showed that the studied gabion walls are stable when subjected to a horizontal acceleration up to 0.4 at the bottom of the wall.