Academic literature on the topic 'Thermal Bridges'

Thesis (M.S.)--West Virginia University, 2005.<br>Title from document title page. Document formatted into pages; contains x, 131 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 115-122).

Integral bridges are generally considered an attractive alternative to conventional bridges presenting the economic advantage of lower construction and maintenance costs. However, the concept of the integral bridge presents other challenges primarily arising from the monolithic connection that exists between the superstructure and the substructure. Thermal loading leads to daily cycles of expansion and contraction superimposed on seasonal cycles. This results in significantly higher soil-structure interaction activity that may lead to excessive earth pressures behind the abutment and potential failure of the soil and structure. A parametric study was carried out to evaluate the impact of change in the backfill soil parameters and change in the season of construction on the earth pressures developed behind the abutment. The frequency of the daily and seasonal cycles of expansion and contraction is such that granular soils respond as fully drained materials. This is seldom the case for fine grained soils. Excess pore pressures are developed and some drainage may occur. However, data and resource limitations make it not feasible to accurately model this over the long term. Further the need to make assumptions about the temperature cycles and the permeability characteristics weakens the strength of the analysis. Therefore, an envelope of earth pressure generation was created in these parametric studies by modelling fine grained soils as fully drained and fully undrained. Plaxis 2D was used to model the bridge and surrounding soil. In developing a realistic model of an integral bridge, the first stage was to simulate a constructed instrumented integral bridge which presented measured values of temperature, deformation and earth pressures in time. This allowed the model to be validated and the sensitivity of the analysis to the parameters assessed. A second simulation was undertaken to compare the output of an integral bridge analysis using Plaxis 2D finite element software with a published study output carried out using the finite difference method. There were a number of challenges to overcome in modelling an integral bridge. These are described in some detail, highlighting the impact the assumptions made within this studies, had upon the output. It was found that the backfill stiffness parameter was the dominant factor that controlled the magnitude of earth pressure. The parametric study revealed that the season of construction affected the earth pressures generated behind the abutment with autumn and summer construction often leading to cumulatively lower earth pressures than spring and winter respectively. In integral bridge construction, it is common to use granular soils in backfill construction. However, the use of granular soils in foundation construction may not be sustainable as a result of material availability and construction cost. Fine grained soils are alternatively used where granular soils are not. It was found that modelling fine grained foundation soils as fully drained and fully undrained produced significant variations in the behaviour of the backfill soil and the resulting earth pressure pattern. It is therefore necessary to take into account the impact of thermal loading on the envelope of earth pressure to ensure that the capacity of the structure and soils are not exceeded or underutilised.

Green design is now a ubiquitous term in the profession of architecture, yet the energy performance of buildings in real-world conditions is poorly documented. A large number of buildings use substantially more energy than is predicted during design, and one possible explanation is that designers do not adequately understand the impact of thermal bridging through insulation on the energy use of a building. This study proposes a methodology that uses the parametric design program Grasshopper to quantitatively analyze infrared images for the degree of thermal bridging in a wall assembly. The end result is a user-friendly tool that architects can use to study the relative energy performance of their buildings in the field, giving them an increased understanding of the energy efficiency of their designs. Case studies of various details show a ten to fifty-five percent reduction in the effective R-value of the overall wall assemblies due to thermal bridging.<br>10000-01-01

Bridges are critical pieces of infrastructure important to public safety and welfare. Fires have the potential to damage bridges and have been responsible for taking many bridges out of service. The hazard fire poses to bridges is a little studied risk unlike more common threats such as impact, scour and earthquake. Information on the rate of occurrence of bridge fires and the mechanisms of structural response of bridges subjected to fire are both vital to policy makers seeking to address the hazard rationally.<br />The investigation presented developed frequency statistics of bridge fire incidents from several sources of vehicle accident and fire statistics. To further investigate the fire hazard a computational model integrating the simulation of large fires and the simulation of bridge superstructure mechanical response was created. The simulation was used to perform a parametric study of fire size and location to investigate the relationship between these parameters and damage tot bridge super-""structure. The statistics investigation resulted in an observed rate of fires due to vehicle accidents of approximately 175 per year. Approximately one of these per year was the result of a tanker truck carrying a flammable liquid leading to extensive superstructure damage. The simulation showed that a tanker fire resulted in permanent damage to the bridge by several measures where as the affects of a bus fire were minimal. The simulations also demonstrated the mechanisms of bridge response; the importance of girder temperature in that response; and the differences in the response to a tanker fire that can lead to collapse.<br>Ph. D.