Seismic Fragility Analysis for Highway Bridges with Consideration of Soil-Structure Interaction and Deterioration

Bridges are critical elements within the highway transportation network. It is very important for the owner or designer to perform the risk assessment of the highway bridges during extreme events, such as earthquakes, due to their importance to the network, commerce, economic vitality and mobility. Recent studies show that seismic fragility curves are useful tools for the seismic risk assessment of highway bridges. Although general seismic fragility approach has been well established in the last two decades and numerous retrofit methods have been applied to highway bridges in New York City (NYC) metropolitan area, which has been classified as moderate seismic zone as per American Association of State Highway and Transportation Officials (AASHTO), there is a need to carry out detailed and further work on seismic fragility by considering soil-structure interaction (SSI) and deterioration effects because of the differences in ground motion characteristics, construction practices and inevitable deterioration of construction materials. The main objective of this research work is to refine existing methods for the development of analytical seismic fragility curves for bridges in NYC metropolitan area by introducing detailed consideration and modeling of the SSI and deterioration of critical bridge elements. To meet above objective, several sets of typical synthetic bedrock and ground surface motions in NYC metropolitan region are developed in this thesis. A detailed soil material modeling along with the sensitivity analysis of the soil properties has been investigated, followed by the development of more reliable SSI model. General deterioration models, for both elastomeric bearings and reinforcement steel deterioration have been constructed. With these investigated and developed models, more realistic structural model for the typical multi-span continuous (MSC) bridges in NYC metropolitan area has been constructed. Nonlinear structural analysis as well as corresponding limit states and probabilistic analysis, have been carried out using this detailed bridge model. Based on analysis results, more realistic and reliable seismic fragility curves, which is the function of peak ground acceleration, for bridge and its components have been developed. The evaluation of seismic fragility curves constructed in this research work shows that typical MSC bridges in NYC metropolitan area would benefit from the consideration of the detailed SSI model and the risk of these bridges experiencing different extents of damage under earthquake disaster decreases because of modeling of SSI effects. However, when these bridges have been in service and have undergone deterioration for 20 years, the risk increases by the same level as the decrease because of inclusion of SSI modeling

Firstborn microcrystallization method to prepare nanocapsules containing artesunate

We developed a novel method to prepare nanocapsules. A solute often crystallizes when its solubility alters from one solvent to another, and its firstborn crystals are used as templates to prepare nanocapsules for the first time, which is called firstborn microcrystallization method. By using this method, the maximum diameter of the nanocapsules including artesunate is about 76 nm, and wrapping state is well. One important advantage of our method is that the preparation of the nanocapsules operates easily and is a one-time process with no other cumbersome processes necessary, therefore avoiding secondary pollution. The proposed method provides a new route to prepare monodisperse nanocapsules to increase bioavailability of hydrophobic solutes

New Method for Numerically Solving the Chemical Potential Dependence of the Dressed Quark Propagator

Based on the rainbow approximation of Dyson-Schwinger equation and the assumption that the inverse dressed quark propagator at finite chemical potential is analytic in the neighborhood of $\mu=0$, a new method for obtaining the dressed quark propagator at finite chemical potential $\mu$ from the one at zero chemical potential is developed. Using this method the dressed quark propagator at finite chemical potential can be obtained directly from the one at zero chemical potential without the necessity of numerically solving the corresponding coupled integral equations by iteration methods. A comparison with previous results is given.Comment: Revtex, 14 pages, 5 figure

Estimating fine-scale visibility in a temperate forest landscape using airborne laser scanning

Visibility is a key factor influencing animal behavior in forest ecosystems. Fine-scale visibility in forested areas has been measured by ground-based approaches at the plot level, using site-specific methods that have limited spatial coverage. Here we examine airborne laser scanning (ALS) as a novel tool to quantify fine-scale visibility in the temperate forests of Germany at a landscape scale. We validate the (vertically derived) ALS-derived visibility measures using proven (horizontally derived) terrestrial laser scanning (TLS) estimates of true visibility. Our results indicate that there is a good agreement between the visibility resulting from ALS and TLS with an R2 ranging from 0.53 to 0.84 and a normalized RMSE varying from 15.92% to 11.81% at various plot sizes, with the highest accuracy achieved using a plot size of 35 × 35 m. Our study demonstrates for the first time that ALS can be successfully applied to quantify fine-scale visibility in temperate forests at a landscape level. This approach holds potential for studying the spatial behavior of animals (e.g., habitat selection and predator–prey relationships) in forest ecosystems.publishedVersio

The Impact of Different Herdsmen’s Size on Grassland Ecosystem of Eastern Transect in Tibetan Plateau: A Case Study from Maqu

In order to address grassland degradation, an individual contracting system, or namely, single-household rangeland management, based on Garrett Hardin theory of “tragedy of the commons”, had been conducted in Maqu since 1980s. Despite the support of local government, such a well-intentioned system saw little fruits on managing degradation, encountering extensive frustration due to its poor practical outcomes. Meanwhile, joint-household rangeland management, as an inheritance of locality-based management, has been vigorously pursued and has played an important role on Maqu’s grassland management system. In order to better illustrate the impact of size on managing the grassland ecosystem, an experiment was set up in which different herdsmen’s scales (single household, small-scale, medium-scale, large-scale, oversized-scale) existing in Maqu grassland was conducted. This study was an attempt to provide a groundbreaking management model, thus inspiring the policy-makers to achieve better solutions