[en] This paper describes the dynamic response to simulated tornadic forces of a nuclear reactor building mounted on a floating platform, moored within a protective breakwater. The time-histories of wind forces are simulated considering the size and layout of the floating nuclear plant (FNP) at several different heights. Due to the strong up-draft and steep pressure gradient at the core of the tornado, the inertial force, usually negligible in winds caused by large scale storms, plays a dominant role in the conversion of wind speed to wind force. Serious underestimation of the wind forces would result if this inertial effect is not considered. The structure considered is a floating platform with the reactor containment shell mounted on it. The eigenvalues and eigenvectors are determined for the platform-building assembly (assumed elastically supported) moored in a basin formed by a rubble mound breakwater. (Auth.)

[en] The paper describes an experimental and analytical investigation of the one-shot impact behavior of reinforced concrete beams subjected to varying periods of accelerated corrosion in seawater with induced current. The objective was to simulate long-term field corrosion and determine the reduction in structural integrity. An instrumented electromagnet-triggered dropweight system was used to determine the load and energy traces of beams supported on an isolation block. Three linear physical models, i.e. beam, two and three-degree-of-freedom spring mass, and a nonlinear finite element model, were used and the analytical energy and load values compared with those from the tests. (orig.)

[en] The paper presents the results of a two-phase experimental investigation on the fatigue and fracture of six different types of concrete: plain, 0.5%, 1.0%, 1.5%, and 2.0% steel fibers and 0.5% kevlar fibers. In the first phase the J-integral was evaluated for different types of concrete from load-displacement curves. The value shows a marked increase in the energy required to fracture concrete when fibers are added. The values did not vary substantially for different notch depths. In the second phase concrete beams were subjected to fatigue by applying a pure bending on the notch. The effect of fiber addition was examined with emphasis on the crack propagation and the increase in the fatigue strength. The crack pattern was mainly influenced by the presence, amount, and the distribution of the fibers in the concrete. (orig./HP)

[en] The dynamic response to seismic forces of a floating nuclear plant restrained by mooring struts attached to the caissons within a protective breakwater is described. The floating platform is idealised as an equivalent thick plate. The reactor building is considered as a uniform shear-bending beam with lumped masses, the properties of which are based on frequency equivalence with the actual containment structure. The linear elastic mooring system with known strut stiffnesses, is idealised using beam elements. The Taft accelerogram is used for the excitation input at the ocean bed level and at all the mooring struts attached to the mooring caissons. Taking into account the hydrodynamic effects of the sea water, the time histories of displacements and stresses at typical sections are evaluated. (author)

[en] This paper describes the calculations of probabilistic dynamic responses to seismic forces of a Floating Nuclear Plant (FNP) Platform restrained by mooring struts attached to caissons, within a protective breakwater. An offshore nuclear power plant, similar to the one proposed for the Atlantic Generating Station, is chosen as the example problem. The FNP is modelled using eight-noded isoparametric plane strain elements. The buoyancy effects are accounted for by boundary elements with appropriate axial stiffnesses. The fluid medium is isolated from the structure, and discretized using two-dimensional plane strain eight-noded isoparametric quadrilateral finite elements with pressures as the nodal unknowns. The fluid structure interaction is simulated by incorporating the hydrodynamic forces, associated with frequency-dependent added mass and damping, as external loading at the interfacial nodes of the FNP platform. (orig.)

[en] This paper describes the dynamic response to simulated tornadic forces of a nuclear reactor building mounted on a floating platform, moored within a protective breakwater. The structure considered is a floating platform with the reactor containment shell mounted on it. The platform consists of a layered rectangular gridwork of bulkheads, and the reactor building is a cylindrical shell with a hemispherical dome. Two kinds of models are considered for the floating platform: 1) A rectangular box grid made up of individual equivalent orthotropic plates, 2) The entire grid assembly replaced by a single equivalent thick plate. The reactor building for both cases is idealised as a uniform shear-bending beam with lumped masses, the properties of which are based on frequency equivalence with the actual containment structure. The eigenvalues and eigenvectors are determined for the platform -building assembly moored in a basin formed by a rubble mound breakwater. The linear elastic mooring system with known strut stiffnesses, is idealised using beam elements. Hydrodynamic effects of the sea water in the basin are included, in view of their significant effect on the response. The fundamental frequency values obtained from plane strain and three-dimensional modelling agree well with those reported by earlier investigators. A time-domain response analysis considering the combined inertia and dynamic effects is carried out for tornadic forces applied directly to the reactor building. The dynamic magnification factor is determined based on the static deflection at the top due to uniform wind speed