Case Studies in Structural Engineering最新文献

The seismic analysis and retrofit of prestressed reinforced concrete bridge is discussed by considering a real case of a viaduct still in use. The unique features of this bridge make this type of bridge particularly interesting, either structurally or architecturally. The paper begins with the analysis of certain particular structural deficiencies that emerged during the viaduct operation. The results of the analysis indicate that the structural performance can be enhanced by only modifying the support devices. The primary structural components are not required to be involved in the retrofitting process. Using the modern seismic code, the upgrading of the viaduct performance is obtained by replacing the old bearing devices on the piers and existing viscous dampers connected abutments to the deck with new modernised ones.

Strain gages are applied to get the strain and stress of a CPR1000 Nuclear Power Plant (NPP) pressurizer during the pre-delivery hydrostatic test. The measured strain curves are discussed to find the deformation features of the cylinder. The stresses of cylindrical base metal, longitudinal welds and girth welds are calculated and compared with the theoretical values. The stresses in girth welds and upper head nozzle welds show non-uniformity at these areas. The possible reasons are discussed for this phenomenon. The stress intensity is calculated and evaluated according to the allowable limit. The fatigue usage factor is evaluated by considering the effect of internal pressure rise-and-fall cycle to pressurizer’s total fatigue life. The evaluated results show that the hydrostatic test has little effect on the integrity or fatigue life of the pressurizer. This test provides the basic deformation data of the pressurizer, which plays an important role in the ageing assessment and management during operation.

A large cinematographic and shopping centre is designed to be built in Tirana. It will be a special structure, partially underground, situated in an excavation of depth 22 m, with a minimum distance of 10 m to a large existing shopping centre. For the first phase of the project, the main engineering challenge was to design a safe and economic structure to ensure the stability of the neighbouring existing shopping centre and the ground itself. This paper is focused on the engineering challenges of the design and construction of the earth retaining structure, which was decided to be a combination of a piled wall and reinforced concrete frames forming a rather complicated structure but a very economical solution. The solution described in this paper made the construction costs drop to 35% of the cost of the initial design. The construction of the earth retaining structure began in 2011 and was successfully completed in 2012. The rest of the project, the commercial centre itself, is still under construction.

The project “Brick-topia” was based on a combination of the latest structural analysis and form-finding computational tools with traditional, cheap and effective construction techniques. It is the result of innovation to fight against budget and time. The initial budget was 3000 euros and only seven weeks was the time to look for sponsors, design the pavilion, plan the construction phases and build it.

The whole process of designing, decision on the materials, structural analysis and construction is presented in the paper, including exploration on new form-finding methods to redesign a project in situ and research on a new formwork system using scaffolding, cardboard, wire and steel rods and having a cutter as main tool.

Strong damage was observed in Colima Mexico on most of the cultural patrimony (mainly churches) after the 2003 M7.5 earthquake. In order to find a correlation between the observed damage on the historical buildings and the earthquake intensity, the vulnerability is assessed by qualitative methods, including the vulnerability class method (VCM) and the vulnerability index method (VIM). The latter method is modified and adapted in this research to assess the seismic vulnerability of historical buildings such as churches and cathedrals located in areas from high to very high seismicity. The results are intended to serve as preliminary indicators of expected damage levels that allow the local authorities to take measures oriented to disaster prevention. The assessment using both methodologies is developed on 15 historical masonry churches, most of them from XIX century. With the results, a correlation between damage and intensity taking into account a Macroseismic Scale is developed and the qualitative methodologies to assess the seismic vulnerability of historical constructions are compared each other.