Response of high-strength steel reinforced concrete structures to simulated earthquakes

In reinforced concrete (RC) structures expected to resist earthquake demands, substituting smaller amounts of high-strength steel for conventional steel reinforcement can help reduce reinforcement congestion and placement costs while keeping strength unchanged. Provided cross-sectional dimensions remain unchanged, reducing the amount of longitudinal steel in a member will result in a member with similar initial stiffness but lower post-cracking stiffness. Nominal strength can be kept nearly the same if this reduction in the amount of steel is accompanied by a corresponding increase in the strength of the steel. The topic of this investigation is whether two frames with the same initial stiffness and nominal strength, but different post-cracking stiffnesses, reach comparable peak drift during a given ground motion. This is a question about drift demand, not drift capacity. The impact of changes in steel strength on drift capacity has been examined by others and is not the subject of this study. Four nominally identical reinforced concrete frames were tested on a unidirectional earthquake simulator. In two frames, conventional reinforcing steel was used in the columns at a reinforcement ratio of 1.8%. In the other two frames, high-strength reinforcing steel was used in the columns at a reinforcement ratio of 0.8%. Each frame was subjected to one of two series (or sequences) of five ground motions. The first four motions were of either increasing intensity (series 1) or decreasing intensity (series 2). The last motion was the strongest used in this study, and had a peak ground acceleration of 1 g, a peak ground velocity of 11 in./sec, and a peak ground displacement of 1.3 in. Comparisons of frames with different post-cracking stiffness, and comparisons of similar frames subjected to different ground motion sequences supported the hypothesis that the dominant factor driving peak drift is initial period calculated using gross cross-sectional properties. To examine further the idea that initial period drives peak drift in RC structures subjected to earthquake demands, a dataset was compiled using results from more than 160 dynamic tests of RC structures and the measured responses of 3 instrumented RC buildings. This dataset was used to evaluate an expression proposed by Sozen (2003) indicating that peak drift is directly proportional to the product of peak ground velocity and initial period (calculated from gross cross-sectional properties). Comparisons of measured-to-estimated peak drift revealed that, for ground motions with PGV/PGA \u3e 0.03 sec, the studied expression produced reasonable and safe estimates of peak drift. Ground motions outside this range have been used in laboratory tests but are unlikely to occur frequently in the field. All the evidence examined suggest that peak drift caused by earthquake demands is proportional to initial period. It follows that replacing conventional steel reinforcing bars with fewer or smaller bars of higher strength is unlikely to result in consistent increases in drift demand, provided the cross-sectional dimensions remain unchanged

GIS Analysis: Hill Top Tree Removal Analysis

https://digitalcommons.tacoma.uw.edu/gis_projects/1025/thumbnail.jp

Universal Test Facility

A universal test facility (UTF) for Space Station Freedom is developed. In this context, universal means that the experimental rack design must be: automated, highly marketable, and able to perform diverse microgravity experiments according to NASA space station requirements. In order to fulfill these broad objectives, the facility's customers, and their respective requirements, are first defined. From these definitions, specific design goals and the scope of the first phase of this project are determined. An examination is first made into what types of research are most likely to make the UTF marketable. Based on our findings, the experiments for which the UTF would most likely be used included: protein crystal growth, hydroponics food growth, gas combustion, gallium arsenide crystal growth, microorganism development, and cell encapsulation. Therefore, the UTF is designed to fulfill all of the major requirements for the experiments listed above. The versatility of the design is achieved by taking advantage of the many overlapping requirements presented by these experiments

Blogging as a Medium of Social Support During the Adoption Process: A Phenomenological Study of Adopting Parent-Bloggers.

The purpose of this research was to investigate the community of support prospective adoptive parents create by way of blogging during the adoption process. This study used phenomenology and grounded theory strategies as they pertain to the qualitative method inquiry to collect data through in depth interviews of nine participants, field notes, blog reading and relating artifacts. In order to get a balanced view of the phenomenon, this study included both blogger and non-blogger adoptive parents, who all participated in subsequent open-ended interviews. To analyze data, I used the following analytical tools: servant leadership, narrative paradigm, social support, and care theories. Completion of this research created greater understanding of how social media invites interactions and connections that may not happen otherwise between people who shared the common purpose to adopt. Findings of this study revealed the following: blogging built a support community for adoptive parents; it offered a place to share information and process emotions; it became a medium for adoptive parents to tell their stories; in particular, writing blogs turned blogging parents into servant leaders whose experience pave the way for future generations. These findings suggest that future prospective adoptive parents could use blogs to research sources and to find support groups both online and otherwise whose help could guide them down the least stressful path of adopting a child

Effects of Warnings on Responsibility Allocation

ABSTRACT Four experiments explored the effects of warnings on people's allocation of responsibility for product safety. Participants read descriptions of accident scenarios in which injuries occurred during the use of products. They then allocated responsibility to the manufacturer, retailer, or consumer (user). Results of two experiments indicated more responsibility was assigned to the consumer and less to the manufacturer when products were accompanied hy a warning (76%-94% to the consumer), compared to a no-warning condition (41%-68%). A third experiment compared responsibility allocations for good versus poor warnings. Consumers were assigned more responsihility (83%) with good warnings than with poor warnings (69%). The fourth experiment again showed warnings played a significant role in the allocations, but injury severity did not. Interactions in all four experiments indicated the role of warnings in responsibility allocations was less for products where the hazards are more obvious. In addition to implications for product safety, the results provide insights into jury decision making regarding the role of warnings in product liability litigation

Warnings

The communication-human information processing (C-HIP) model ) is a framework showing Warning

Performance of Mud Mortar Walls Under Seismic Loading

The inherently brittle nature of unreinforced masonry structures results in poor performance during earthquakes, presenting major hazards to communities. Many of these structures found in Nepal were severely damaged or destroyed during two earthquakes in 2015. The purpose of this project is to test the effect on seismic response of several modifications to stone and mud mortar structures. These structures are common in many areas of Nepal. Two T-shaped stone and mud mortar masonry walls are constructed. The first wall has no modifications and represents current building practices. The second wall uses steel wire mesh as external reinforcement. Each wall is subjected to simulated strong ground motions of increasing intensity until failure. The results are expected to indicate better toughness during an earthquake as a result of the steel reinforcement. Therefore, these results can be applied in regions like Nepal in an effort to avoid a repeat of the catastrophic damage seen in 2015

The Institute’s Team for Damage Investigations

ACI Committee 133, Disaster Reconnaissance, was conceived in the aftermath of the 2010 Chilean Earthquake, an event that affected thousands of structures. That event caused extensive damage to an estimated 50 to 100 mid-rise and high-rise reinforced concrete (RC) buildings, including seven that were damaged beyond repair.1-3 Although ACI has had a strong history of publishing assessments of disasters (refer to textbox: Historical Disasters Examined in ACI Publications), the Institute had no formal mechanism in place to deploy a team to investigate and report on critical lessons to its technical committees and membership. Furthermore, the broadening international reach of the ACI 318 Building Code, which has been adopted or referenced in the national code of more than 30 countries, including Chile,4 highlighted the need for ACI liaisons to be on the ground immediately after a disaster to serve as a technical resource to local engineers. Recognizing these needs, former ACI Committee 318 Chair Jack Moehle consulted with former ACI Presidents José Izquierdo-Encarnación and Luis García about the formation of a committee with a disaster reconnaissance directive. In October 2012, a proposal was submitted to the ACI Board of Direction to establish and fund a new committee with the primary objectives of: Providing a mechanism for evaluating the application of ACI documents internationally; and Disseminating deployment findings to ACI technical committees and through ACI publications.5 To date, the Chairs of the resulting committee, ACI Committee 133, have included Jack Moehle, Ken Elwood, Michael Kreger, and Santiago Pujol. This committee has actively engaged a diverse group of practitioners and researchers

Can brewer-sponsored ‘drink responsibly’ warning message be effective without alcohol policies in Nigeria?

Alcohol availability, use and misuse and their related problems are rising in many parts of the African continent and this has been attributed to many factors such as non-existent or ineffective regulatory measures. In contemporary Nigeria, while a culture of intoxication is growing, there are no regulatory measures in the form of alcohol policies to reduce it. What exists is brewer-sponsored self-regulation. This paper therefore, critically analyses this self-imposed 'drink responsibly' warning message, arguing that because responsible drinking messages are strategically designed to serve the interest of alcohol industries, it cannot be effective. The paper further argues that because there are no definitions of standard drinks and where alcohol by volume (ABV) is scarcely inscribed on product labels of alcoholic beverages, such message will remain ineffective. Therefore, it recommends that an urgent step should be taken by the government to formulate and implement comprehensive evidence-based alcohol policies in Nigeria