The objectives of the research were threefold. Firstly, to improve .the numerical modelling capability for reinforced embankments constructed over soft compressible soils containing vertical drains. Secondly, to demonstrate the ability to model accurately such embankments. Finally, to develop simplified procedures to be used in the design of embankments over soft soils. The modifications to the finite element program, CRISP, included the incorporation of three additional elements: modelling the reinforcement, the soil/reinforcement interface and the vertical drains. The facility to vary permeability with stress level was also implemented. A technique for modelling the consolidation of soil containing vertical drains in plane strain finite element analyses was developed and validated. The modified program was validated in three ways. Firstly, each element was used to analyse simple problems so that the correct formulation was ensured. Secondly, a series of analyses was carried out of problems for which analytical solutions were available; these problems involved collapse of undrained sub soils and consolidation around a single vertical drain. Thirdly, an analysis of a case history of an embankment constructed over a normally consolidated clay, improved with vertical drains, was performed. Based on the results of the previous finite element analyses, and an additional analysis of an idealized two-stage constructed embankment, simple design procedures have been proposed. Firstly, a method for the design of single stage embankments and, secondly, a method for the calculation of subsoil strength increases in multi-stage construction, which can be used in conjucntion with limit equilibrium analyses. It is concluded that the finite element method is a useful technique for the analysis of reinforced embankments over soft soils containing vertical drains.

This thesis describes an experimental study undertaken to examine the influence of joint resistance to in-plane moments on the performance of steel columns and complete frames. The principal objective of the tests was to provide experimental data against Which sophisticated computer analysis programs may be verified. Details of the experimental study of 22 joint tests, eight column subassemblages, and two three storey, two bay steel frames are reported. It is demonstrated that all beam to column connections have an inherent degree of stiffness and that their moment-rotation characteristics are non-linear. The load carrying capacity of columns, confined to buckle in-plane, is shown to be enhanced considerably by the resistance to rotation provided by simple beam to column connections. In frames incorporating flange cleat connections the beams and columns can sustain greater loading and deflect less than is predicted by current design models. The assumptions of pin-ended columns and simply supported beams are shown to be conservative. Comparisons of the results of the column and frame tests with two finite element analysis programs are presented. The use of computer programs for semi-rigid design as well as the development of a simple approach are discussed.

This thesis reports the research investigation on the behaviour of non-sway frames with SHS columns taking into consideration the influence of semi-rigid flowdrill connections. The aim of the studies was to investigate the behaviour of the non-sway frames in the elastic and inelastic ranges, the acceptability of the flowdrill connections for low-rise non-sway frames and to develop a simplified semi-rigid design that is suitable for daily design routine. The analytical studies were conducted using an existing finite element program which was modified to work with frames employing tubular columns. The program is able to simulate the response in the elastic and inelastic ranges taking into account the semi-rigid connections, the geometrical and material nonlinearities and the development of spread yield. The program has been validated against the experimental results and can reasonably predict the true frame behaviour. The results of the parametric studies show several important observations;one of which is the phenomenon of moment shedding. This phenomenon causes the relaxation of the detrimental moment at the column top end which in turn causes the moment redistribution to the neighbouring members. Eventually, the detrimental column moment diminishes and sometimes acts as restraining moments. As a consequence, at ultimate load, the columns behave in the general form of axially loaded compression members and the beams as simply supported with a certain degree of end restraint. Knowing that restrained beam-columns can be treated as axially loaded, extensive parametric studies on different frame configurations were conducted to determine the ultimate strength of beam-columns. The studies were conducted on low rise multi-storey non-sway frames. The principal parameters varied are the column slenderness, connection types and the magnitude of beam loads. The values of ultimate strength of restrained beam-columns are compared directly against the strength of pin ended columns as specified by the BS 5950 and EC3 codes. The results show that in many cases, the ultimate strength of restrained beam-columns are in excess to the strength of axially loaded pin ended column as specified by BS 5950 and EC3. Based on the results of the parametric studies, a simplified design for simple, semi-rigid and rigid frames is developed. The columns are designed as axially loaded compression members without any consideration of eccentricity or partial fixity moments. The beams for simple construction are designed as simply supported with pin ends; whereas, the beams for semi-rigid and rigid construction are designed as simply supported with a certain amount of end restraint moment to take into account the effect of semi-rigid and rigid connections. The design of strength for beams and columns can be carried out individually and is not dependent on the stiffnesses of the M-0 of the connections, beams and columns. Finally, general conclusions and recommendations for further work are also included.

This thesis describes research work undertaken to examine the influence of joint resis- tance to in-plane moments on the assessment of five fun scale two dimensional steel frames. All the available information has been collected into a form which is readily usable by the wider research community. The findings have been used to develop improved semi-rigid design methods. Details of the experimental results of five frames are discussed and reported. A variety of joint types were tested, each type of joint exhibited some degree of moment and rota- tional stiffness, leading to frame responses involving significant interaction between beams and columns. This affects both beam and column deflections, the pattern of frame mo- ments, ultimate capacity of members and collapse modes. The principal objective of the tests was to provide experimental data against which two in house sophisticated computer analysis programs may be verified. Details of modifications to an existing databank of the moment-rotation test results to provide a more efficient and user friendly tool for research workers are explained. The main objective of the work described herein was to investigate the influence of semi-rigid connection behaviour on a wide range of subassemblage configurations. A new method for the non-sway column design is developed and validated using the test and analytical results. The new approach is found to be more economical than the existing BS 5950 method but it still essentially conservative. The methods to design the lateral restraint beam including the serviceability and ultimate limit states are also proposed and examined. The most important feature is that the precise form of the M-Ø responses are not important for the semi-rigid design. Finally, a complete set of design methods is advised to take into account the inherent strength and stiffness of semi-rigid joint.

This thesis describes a combined analytical and experimental investigation into the influence of human occupants on the dynamic properties of civil engineering structures. This is an increasingly important issue in the design of assembly structures against human-induced vibrations. An analytical parametric study demonstrated that a damped single degree of freedom (SDOF) model of one or more human occupants can explain (1) natural frequency increases and decreases, (2) additional natural frequencies, and (3) response reductions, reported in the literature. Experimental investigations employed a lightly damped simply supported prestressed concrete beam spanning 11 m and weighing 15 tonnes. The influence of up to five stationary humans on the modal properties of this laboratory based, but realistic, full-scale test structure was quantified. For this purpose, natural frequencies, damping ratios, mode shapes, and modal masses were estimated by curve-fitting of measured frequency response functions. It was shown that the occupants affected the three investigated vertical bending modes of the test structure (at about 4.5 Hz, 17 Hz, and 38 Hz). The occupants most significantly increased damping and it was established that the location, the posture and the number of occupants were important. Within the range of low-level vibrations studied, the level of vibration of the structure had only little effect. The combined analytical studies and experiments demonstrated that the presence of groups of stationary humans can be modelled by a damped 'human' SDOF system attached to the 'structural' SDOF system representing a well separated mode of an empty assembly structure. Based on the obtained experimental data, the mass, frequency and damping properties (mH, f and ýH) of a damped SDOF model of groups of sitting occupants were derived. It was established that these properties varied with the natural frequency of the structural system. It was found that mH decreases while fH and ýH increase with increasing natural frequency of the empty structural system. Based on these findings, mH should be assumed to be greater than 60% of the total mass of occupants, fH smaller than approximately 9 Hz and ýH less than 40% in the case of empty structures with natural frequencies below about 17 Hz. The derived damped SDOF human model was used to quantify the influence of occupants on the dynamic response of a range of structures modelled as SDOF systems. These data are provided in the form of design charts. They can, until further information becomes available, be used to estimate dynamic responses of civil engineering structures occupied by sitting humans to sinusoidal excitation.

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