Non-Linear Analysis Of A Nuclear Containment Structure Under High Internal Pressure

The main objective of the current study is to investigate the response of an internally pressurized nuclear power plant containment structure at pressure values higher than design pressure, and is focused on the response of prestressed concrete containment to ultimate global structural failure. The containment structure consists of a prestressed concrete cylindrical perimeter wall, with a prestressed concrete tori-spherical dome, prestressed concrete ring beam, and conventionally reinforced concrete base slab. The finite element program ANSYS is used to predict the non-liner behaviour of the containment structure. Different techniques available in ANSYS program to model steel reinforcements for reinforced concrete and prestressed concrete is estimated to define a more suitable approach to model prestressing system. The approach proposed here is capable of incorporating parameters such as variation in tendon layout and non-uniform prestress losses in comparison to those done by other researchers. It is concluded that the design criteria for the containment structure are fully satisfied. No through crack was observed at design pressure. The first through crack develops in the dome at a pressure of 2.1 times the design pressure. There is no damage to be expected to the reactor systems up to a pressure well above design pressure. It is observed that the containment structure subject of this study meets the design requirement of the current standards and behaves linearly in excess of 1.5 times the design pressure. The response of the internally pressurized containment structure including the major openings is investigated. It is concluded that presence of openings does not have a significant effect on the pressure capacity of the containment structure. The minor differences in the responses are at pressure values beyond the linear limit and are less than 5%. The response when openings are included are very similar to those without openings, except at the immediate neighboring of the equipment airlock opening. It is concluded that to predict the pressure response of containment structure, including the openings can be ignored. In case of need for a more exact response, only the equipment airlock can be included in the model

Non-Linear Analysis Of A Nuclear Containment Structure Under High Internal Pressure

The main objective of the current study is to investigate the response of an internally pressurized nuclear power plant containment structure at pressure values higher than design pressure, and is focused on the response of prestressed concrete containment to ultimate global structural failure. The containment structure consists of a prestressed concrete cylindrical perimeter wall, with a prestressed concrete tori-spherical dome, prestressed concrete ring beam, and conventionally reinforced concrete base slab. The finite element program ANSYS is used to predict the non-liner behaviour of the containment structure. Different techniques available in ANSYS program to model steel reinforcements for reinforced concrete and prestressed concrete is estimated to define a more suitable approach to model prestressing system. The approach proposed here is capable of incorporating parameters such as variation in tendon layout and non-uniform prestress losses in comparison to those done by other researchers. It is concluded that the design criteria for the containment structure are fully satisfied. No through crack was observed at design pressure. The first through crack develops in the dome at a pressure of 2.1 times the design pressure. There is no damage to be expected to the reactor systems up to a pressure well above design pressure. It is observed that the containment structure subject of this study meets the design requirement of the current standards and behaves linearly in excess of 1.5 times the design pressure. The response of the internally pressurized containment structure including the major openings is investigated. It is concluded that presence of openings does not have a significant effect on the pressure capacity of the containment structure. The minor differences in the responses are at pressure values beyond the linear limit and are less than 5%. The response when openings are included are very similar to those without openings, except at the immediate neighboring of the equipment airlock opening. It is concluded that to predict the pressure response of containment structure, including the openings can be ignored. In case of need for a more exact response, only the equipment airlock can be included in the model

A Finite Element Parametric Study of Reinforced Concrete Horizontally Circular Deep Beams

A parametric study of twenty-five reinforced concrete ring deep beams using finite element analysis is presented in this study. This paper took into account the kind of loading (partial and complete), the diameter, depth, and width of the ring beam, as well as the NO. of supports. When compared to equivalent concentrated central loading, acting a central partial distributed loading of 25-100 percent of the length of span increased capacity of load by about 3-80 percent while decreasing max. deflection and moments of torsion by about 4-14 percent and 1-9 percent, respectively. Decreases in load capacity of about 10-33 percent were observed when beam diameter was increased by 20-80%, while deflection and moments of torsion increased by about 30-145 percent and 8-23 percent, respectively. When the depth of the beam was increased by 12-50 percent, the capacity of load and moments of torsion increased by about 15-61 percent, while deflection reduced by about 8-21 percent. When the circular beam width was increased by 40-160 percent, the capacity of load, deflection, and moments of torsion increased by about 142-690 percent, 26-62 percent, and 137-662 percent, respectively. Finally, when the NO. of supports increased by 25-150 percent, the capacity of load increased by about 70-380 percent, while the deflection and moments of torsion decreased by about 27-71 percent and 16-72 percent, respectively.

Simplified Design of Masonry Ring-Beams Reinforced by Flax Fibers for Existing Buildings Retrofitting

Seismic events have repeatedly highlighted the vulnerability of existing masonry buildings. Seismic retrofitting is frequently focused on improving the connection between walls and roof for ensuring behavior able to resist loads from any horizontal direction. This paper deals with the design of masonry ring-beams made of clay bricks reinforced by natural fibers. Various solutions to ensure a masonry building box-behavior are possible, but this is a good combination of both static and conservation requirements, as it allows the use of bio-composites and grouts. It is a relevant possible alternative to the traditional reinforced concrete ring-beams, which are proven to be very ineffective under earthquakes. A simplified model for designing clay brick beams reinforced by flax fibers is provided, and a comparison with customary and traditional floor/roof masonry ring-beams is carried out.

Vaults, roof truss and walls interaction issue in monumental masonry structures

The paper discusses the subject of interaction between a roof truss, vaults and load-bearing walls in a masonry monumental structure. The static structural analysis of the Assumption of the Blessed Virgin Mary Basilica in Bialystok, as an example of Polish neogothic architecture from the turn of the 19th and 20th centuries has been carried out. The building consists of a three-aisled masonry walls system, which in cooperation with cross-ribbed vaults and a timber roof truss determine the spatial rigidity of the structure. Lack of concrete ring-beams and horizontal oriented ceiling slabs cause global stiffness reduction to the horizontal loads. In the past, it could have been one of the main reason for the appearance of cracks in the structure. The basic aspect having a real influence on building global behaviour is interaction of load-bearing structural parts. This structure was subjected to the static analysis with an investigation about the influence of interaction between the roof truss, vaults and walls. The values of horizontal displacements of walls were compared as a result of wind pressure acting on the structure. Numerical calculations were carried out using finite element method.