IMPROVING DUCTILITY OF SLENDER REINFORCED CONCRETE SHEAR WALLS WITH FRP SHEETS AND SPLAY ANCHORS

The Sylmar earthquake of 1971 caused significant damage to slender, non-ductile reinforced concrete (RC) shear wall buildings in California. A later survey by the Concrete Coalition in 2011, under the guidance of EERI members, indicated that there are over 3000 vulnerable concrete buildings in California [8]. This led to City of Los Angeles (LA) Ordinance 193893 enacted in 2015, which requires mandatory upgrades to these concrete buildings by 2035. Current practice to meet the requirements of this ordinance, with respect to RC wall buildings, involves adding new shear walls to the building plan or increasing the cross-sectional area of existing walls using shotcrete. Both options are invasive, costly, and time consuming as they increase the strength of the walls, requiring additional upgrade of the slabs and foundation. The experimental test program described in this report, occurring at the California Polytechnic State University (Cal Poly), College of Architecture and Environmental Design (CAED) High Bay Laboratory, will consist of a non-ductile reinforced concrete (RC) wall modelled after pre 1980’s walls. The shear wall will be retrofitted with fiber reinforced polymer (FRP) sheets wrapped around the wall boundary elements over the height of the plastic hinge region. The goal of this retrofit application is to provide improved confinement of the concrete to increase the ductility of the wall, with minimal increase in strength. The collaborative team of industry members, faculty advisors, and student researchers hopes to see improvements in the compressive strain capacity in the boundary element concrete and increase the global displacement capacity. FRP splay anchors are also used to prevent delamination of the FRP sheets bonded to the concrete. This report provides a literature review of past FRP use on RC shear walls, specimen design, experimental test setup, and the construction approach. If effective, this retrofit strategy will provide a cost and time efficient means of improving the seismic performance of slender, non-ductile concrete structures with walls as the primary lateral force resisting system

Improving Ductility of Slender Reinforced Concrete

The Sylmar earthquake of 1971 caused significant damage to slender, non-ductile reinforced concrete (RC) shear wall buildings in California. A later survey by the Concrete Coalition in 2011, under the guidance of members of the Earthquake Engineering Research Institute (EERI), indicated that there are over 3000 vulnerable concrete buildings in California [8]. This led to City of Los Angeles (LA) Ordinance 193893 enacted in 2015, which requires mandatory upgrades to these concrete buildings by 2035. Current practice to meet the requirements of this ordinance, with respect to RC wall buildings, involves adding new shear walls to the building plan or increasing the cross-sectional area of existing walls using shotcrete. Both options are invasive, costly, and time consuming as they increase the strength of the walls, requiring additional upgrade of the slabs and foundation. The experimental test program described in this report, being conducted at the California Polytechnic State University (Cal Poly) College of Architecture and Environmental Design (CAED) High Bay Laboratory, will consist of a non-ductile reinforced concrete (RC) wall modelled after pre-1980’s walls. The shear wall will be retrofitted with fiber reinforced polymer (FRP) sheets wrapped around the wall boundary elements over the height of the plastic hinge region. FRP splay anchors will also be used to prevent delamination of the FRP sheets bonded to the concrete. The goal of this retrofit application is to provide improved confinement of the concrete to increase the ductility of the wall, with minimal increase in strength. The collaborative team of industry members, faculty advisors, and student researchers hopes to see improvements in the compressive strain capacity in the boundary element concrete and increase the global displacement capacity of the wall. This report provides a literature review of past FRP use on RC shear walls as well as specimen design, experimental test setup, and the construction approach for the Cal Poly wall test program. If effective, the proposed FRP retrofit strategy will provide a cost and time efficient means of improving the seismic performance of slender, non-ductile concrete walls

The Use and Performance of IntensiveRotational Grazing Among Wisconsin Dairy Farms in the 1990s

Growing numbers of Wisconsin dairy farmers have reported success using management intensive rotational grazing (MIRG) techniques that rely on pastures as the primary source of forage for their milking herds. The Program on Agricultural Technology Studies (PATS) has been tracking the use and performance of MIRG systems in Wisconsin since the early 1990s through periodic, large-scale, random sample surveys and on-farm interviews with Wisconsin farmers. Utilizing recent results from the PATS 1997 and 1999 Wisconsin Dairy Farm Polls, this report provides an important update to previous PATS reports. In our surveys, the dairy farmers who report utilizing pastures for forage are a diverse group. Grazing practices ranged from moving livestock several times a day through an extensive network of improved pasture paddocks to grazing the same large field all summer long. For purposes of maintaining consistency, in analyzing our data we defined MIRG as a system in which dairy farmers rely on pastures for at least part of the forage ration of their milking cows and move these cows to fresh pastures at least once a week. Farms that utilized pastures to obtain forage for their milking cows, but did not rotate their cows to a fresh pasture at least once a week, were classified as non-intensive grazing operations. Farm operations that did not rely on pasture for any part of their forage ration were categorized as confinement systems. On our 1999 survey, 22 percent of farmers reported using MIRG systems, 22 percent used pastures non-intensively, and 56 percent used full confinement systems

Management Intensive Rotational Grazingin Wisconsin: the 1990s

Growing numbers of Wisconsin dairy farmers have reported success using management intensive rotational grazing (MIRG) techniques that rely on pastures as the primary source of forage for their milking herds. The Program on Agricultural Technology Studies (PATS) has been tracking the use and performance of MIRG systems in Wisconsin since the early 1990s through periodic large-scale, random sample surveys of Wisconsin dairy farmers. This fact sheet incorporates recent results from PATS 1999 Dairy Farmer Poll into an overall summary of PATS grazing research

Construction of silicon nanocolumns with the scanning tunneling microscope

Voltage pulses to a scanning tunneling microscope (STM) are used to construct silicon columns of 30–100 Å diameter and up to 200 Å height on a silicon surface and on the end of a tungsten probe. These nanocolumns have excellent conductivity and longevity, and they provide an exceptional new ability to measure the shapes of nanostructures with a STM. This construction methodology and these slender yet robust columns provide a basis for nanoscale physics, lithography, and technology

Persuading consumers to reduce their consumption of electricity in the home

Previous work has identified that providing real time feedback or interventions to consumers can persuade consumers to change behaviour and reduce domestic electricity consumption. However, little work has investigated what exactly those feedback mechanisms should be. Most past work is based on an in-home display unit, possibly complemented by lower tariffs and delayed use of non-essential home appliances such as washing machines. In this paper we focus on four methods for real time feedback on domestic energy use, developed to gauge the impact on energy consumption in homes. Their feasibility had been tested using an experimental setup of 24 households collecting minute-by-minute electricity consumption data readings over a period of 18 months. Initial results are mixed, and point to the difficulties of sustaining a reduction in energy consumption, i.e. persuading consumers to change their behaviour. Some of the methods we used exploit small group social dynamics whereby people want to conform to social norms within groups they identify with. It may be that a variety of feedback mechanisms and interventions are needed in order to sustain user interest

Smart Antennas Made Practical: The SPIDA Way

Smart antennas are a specific type of directional antenna able to dynamically control the gain as a function of direction. This contrasts with more traditional directional antennas, where the dynamic ability is missing, and with omni-directional antennas, which are designed to have equal gain in all directions

Wisconsin Dairy Farmer Views onUniversity Research and Extension Programs

Over the last decade, the Program on Agricultural Technology Studies (PATS) at the University of Wisconsin-Madison has received a wide range of formal and informal comments from Wisconsin farmers regarding the direction of university research and extension programs. In an era of declining Extension budgets, increasing privatization, and a rapidly changing farm structure, the debate about where to focus scarce public resources takes on an added significance. Is there still an important role for land grant institutions to play in agriculture in the new century? If so, how can limited resources be targeted most effectively? What do farmers and other citizens want from the land grant system? In order to systematically solicit farmer feedback on these issues, a series of questions about research and extension programs at the University of Wisconsin was included in the PATS 1999 Wisconsin Dairy Farm Poll, a statewide survey sent to 1,600 randomly selected dairy farmers. While the results summarized below focus primarily on the responses of dairy farmers, similar questions were asked of other types of farms in a separate survey sent out at the same time. In general, the response patterns of the nondairy farmers were similar to those of the dairy farm sample