The test results were then used to calibrate a finite element model of a bridge column. This bridge column model was incorporated into a hybrid model of a typical California overpass bridge and tested using the hybrid simulation technique. The finite element model of the typical California overpass bridge was validated using the data from hybrid simulations. The validated model of the typical bridge was used to evaluate its post-earthquake truck load capacity in an extensive parametric study that examined the effects of different ground motions and bridge modeling parameters such as the boundary conditions imposed by the bridge abutments, the location of the truck on the bridge, and the amount of bridge column residual drift. The principal outcomes of this study are the following findings.

Evaluation of the post-earthquake capacity of a bridge to carry self-weight and traffic loads is essential for a safe and timely re-opening of the bridge after an earthquake. Although modern highway bridges in California designed using the Caltrans Seismic Design Criteria are expected to maintain at minimum a gravity load-carrying capacity during both frequent and extreme seismic events, as of now, there are no validated, quantitative guidelines for estimating the remaining load carrying capacity of the bridges after an earthquake event. In this study, experimental and analytical methods were combined to evaluate the post-earthquake traffic load carrying capacity of a modern California highway overpass bridge. An experimental study on models of circular reinforced concrete bridge columns was performed first to investigate the relationship between earthquake-induced damage in bridge columns and the capacity of the columns to carry axial load in a damaged condition. The earthquake-like damage was induced in the column specimens in bi-lateral quasi-static lateral load tests. The damaged column specimens were then tested in compression to failure to evaluate their remaining axial load strength. It was found that well-confined modern bridge columns loose approximately 20% of their axial load capacity after sustaining displacement ductility demands of 4.5 in both principal directions of the bridge. Typical California highway overpass bridges are designed such that they are not expected to develop displacement ductility demands larger than 4.0 in design-basis earthquake events. These test results were used to calibrate a finite element model of a bridge column. This bridge column model was incorporated into a hybrid model of a typical California overpass bridge and tested using the hybrid simulation technique. This typical bridge is a straight 5-span overpass with single-column bents. During these hybrid simulations a heavy truck load was applied on the bridge immediately after the earthquake to study the behavior of the damaged bridge under such truck load. The hybrid bridge model safely carried the applied truck load after surviving an earthquake that induced displacement ductility demands of 4.7 and 6.7 in the longitudinal and transverse direction of the bridge, respectively. The finite element model of the typical California overpass bridge was validated using the data from hybrid simulations. The validated model of the typical bridge was used to evaluate its post-earthquake truck load capacity in an extensive parametric study that examined the effect of different ground motions and bridge modeling parameters such as the boundary conditions imposed by the bridge abutments, location of the truck on the bridge, and amount of bridge column residual drift. The principal outcomes of this study are the following findings. A typical modern California highway bridge overpass is safe for traffic use after an earthquake if none of its columns failed, i.e. none of the column main reinforcing bars fractured, and if its abutments are still capable for restraining torsion of the bridge deck about its longitudinal axis. If any of the columns failed, i.e. if broken column reinforcing bars were discovered in a post-earthquake inspection, the bridge should be closed for regular traffic. Emergency traffic with weight, lane and speed restrictions may be allowed on a bridge whose columns failed if the abutments can restrain torsion of the bridge deck. These findings pertain to the bridge configuration investigated in this study. Additional research on the post-earthquake traffic load capacity of different bridge configurations is strongly recommended.

"TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 440, Performance-Based Seismic Bridge Design (PBSD) summarizes the current state of knowledge and practice for PBSD. PBSD is the process that links decision making for facility design with seismic input, facility response, and potential facility damage. The goal of PBSD is to provide decision makers and stakeholders with data that will enable them to allocate resources for construction based on levels of desired seismic performance"--Publisher's description.

This is the proceedings of the 4th International Conference on Strain-Hardening Cement-Based Composites (SHCC4), that was held at the Technische Universität Dresden, Germany from 18 to 20 September 2017. The conference focused on advanced fiber-reinforced concrete materials such as strain-hardening cement-based composites (SHCC), textile-reinforced concrete (TRC) and high-performance fiber-reinforced cement-based composites (HPFRCC). All these new materials exhibit pseudo-ductile behavior resulting from the formation of multiple, fine cracks when subject to tensile loading. The use of such types of fiber-reinforced concrete could revolutionize the planning, development, dimensioning, structural and architectural design, construction of new and strengthening and repair of existing buildings and structures in many areas of application. The SHCC4 Conference was the follow-up of three previous successful international events in Stellenbosch, South Africa in 2009, Rio de Janeiro, Brazil in 2011, and Dordrecht, The Netherlands in 2014.

Post-earthquake highway bridge repair is an ever-present part of the lifecycle of transportation systems in seismic regions. These repairs require multi-level decisions involving various stakeholders with differing values. The improvement of the repair decision process, repair decision itself, and repair decision outcomes, requires an evaluation of current practices in post-earthquake repair decision-making. This dissertation assesses these current practices within the California Department of Transportation (Caltrans), outlines areas where the current process is ineffective, and highlights areas for improvement. Current repair decision-making practice is focused on the repair of individual bridges given a limited set of established repair methods. To improve upon these practices, this dissertation presents the Bridge Repair Decision Framework (BRDF), a new and unique methodology that allows for simultaneous consideration of all earthquake-damaged bridges as individual elements of a larger regional transportation system. This systematic approach enables the achievement of short- and long-term transportation system performance objectives while accounting for engineering, construction, financing, and public policy constraints. Furthermore, the BRDF allows for continuous refinement of the decision-making process to incorporate engineering and construction innovations, changes in the financial and public policy environment and, most importantly, changes in transportation system performance goals. While existing methodologies allow the incorporation of some of these changes, the BRDF provides a flexible structure that can account for all of these changes simultaneously. This is accomplished through a rigorous, performance-based, and risk-informed decision-making approach that presents repair decisions using a traditional engineering demand-capacity inequality. As a result, the BRDF empowers decision-makers with a holistic understanding of the transportation network condition on a microscopic (bridge) as well as macroscopic (overall system) level. The BRDF also accounts for the probabilistic nature of the earthquake hazard, bridge seismic capacity, and subsequent repair decisions, providing decision-makers with transparency regarding the uncertainties of system condition, repair method reliability, construction workforce availability, and public and business risks. BRDF decision-outcomes are technology-neutral as a result, greatly expanding the range of repair method alternatives that a decision-maker may consider while allowing for tradeoffs to be made between performance, cost, and time in light of transportation system condition and constraints. The BRDF is validated using a simulated bridge system case study that requires post-earthquake repair. This study was designed to demonstrate the functionality of the framework and to examine two alternate decision-making strategies: one with complete and the other with incomplete post-earthquake bridge damage state information. This case study led to refinements in the framework and insights about the benefits of additional information on the damage state of bridges in terms of overall repair time and cost of the regional transportation system. Additionally, the validation revealed areas where the current BRDF can be improved in future studies. The BRDF was created for large public transportation organizations such as the California Department of Transportation (Caltrans), where implementation of the BRDF requires several important prerequisites, including new database creation and additional training for engineers. Once implemented however, the BRDF allows decision-makers to potentially reduce repair costs and times, minimize system downtime, make better investments, and account for transportation system performance goals given current financial and public policy constraints.

Focusing on fundamental principles, Hydro-Environmental Analysis: Freshwater Environments presents in-depth information about freshwater environments and how they are influenced by regulation. It provides a holistic approach, exploring the factors that impact water quality and quantity, and the regulations, policy and management methods that are necessary to maintain this vital resource. It offers a historical viewpoint as well as an overview and foundation of the physical, chemical, and biological characteristics affecting the management of freshwater environments. The book concentrates on broad and general concepts, providing an interdisciplinary foundation. The author covers the methods of measurement and classification; chemical, physical, and biological characteristics; indicators of ecological health; and management and restoration. He also considers common indicators of environmental health; characteristics and operations of regulatory control structures; applicable laws and regulations; and restoration methods. The text delves into rivers and streams in the first half and lakes and reservoirs in the second half. Each section centers on the characteristics of those systems and methods of classification, and then moves on to discuss the physical, chemical, and biological characteristics of each. In the section on lakes and reservoirs, it examines the characteristics and operations of regulatory structures, and presents the methods commonly used to assess the environmental health or integrity of these water bodies. It also introduces considerations for restoration, and presents two unique aquatic environments: wetlands and reservoir tailwaters. Written from an engineering perspective, the book is an ideal introduction to the aquatic and limnological sciences for students of environmental science, as well as students of environmental engineering. It also serves as a reference for engineers and scientists involved in the management, regulation, or restoration of freshwater environments.

The 1994 Northridge Earthquake severely damaged many of the structures at the I-14/I-5 interchange near Los Angeles, California. Most of the bridges at this location were removed and replaced. Many new and challenging aspects of seismic bridge design were implemented into the construction of these structures in an extremely short amount of time. In this paper I will concentrate on one of the ramps which had the old structure removed and the new structure completed and open to traffic in just one hundred seventy-one days after the earthquake.