Developing a Comprehensive Business Planning Extension Program

The Tomorrow\u27s Top Agricultural Producer program was developed to assist agricultural producers in planning. Through the use of highly intensive classroom lectures, a case study reference guide, and mentor committees, the program assists agricultural producers in the development and implementation of a complete business plan

Skewed Steel Bridges, Part I: Effect of Cross-Frame Layout on Lateral Flange Bending Stresses

Lateral flange bending stresses can arise from a number of sources, such as wind loading or eccentric concrete placement, but of particular interest are lateral flange bending stresses, fl, that occur due to skew. Lateral flange bending stresses that occur in skewed bridge systems tend to develop due to lateral forces transferred through cross-frames which may connect adjacent girders at different span points. In lieu of a refined analysis, the AASHTO-LRFD Bridge Design Specifications currently permit engineers examining bridges skewed more than 20° to use a minimum value of fl = 10 ksi for an interior girder and fl = 7.5 ksi for an exterior girder. The estimates for fl provided within the AASHTO-LRFD Bridge Design Specifications are based on a limited data set for skewed bridges. Additionally, since the AASHTO-LRFD Design Specifications state that cross-frames or diaphragms should be placed in a staggered configuration when a bridge is skewed more than 20°, the approximate values provided for fl should not be expected to be indicative of the lateral flange bending stresses experienced when cross-frames are instead carried parallel to the skew in bridges skewed beyond 20°. Carrying cross-frames and diaphragms parallel to the skew angle in bridges skewed more than 20° is a practice implemented by some state DOTs, and is primarily done to minimize problems with cross-frame fit-up during erection. The authors have performed a study to investigate the effects of cross-frame orientation and skew angle upon lateral flange bending stresses, by examining lateral flange bending stresses in a suite of detailed 3D, solid finite element analyses of skewed bridge systems, in which cross- frame layout, spacing, and skew angle were varied. Skewed bridge systems with cross-frames placed parallel to the skew angle as well as systems with cross-frames arranged in a staggered configuration were considered. The models included both material and geometric nonlinearities to assess the lateral flange bending stresses in the different bridge systems. The findings of this study showed that cross-frames placed parallel to the angle of skew produced significantly lower values for fl than cases in which cross-frames were placed perpendicular to the girder line and staggered. Both reducing the skew angle and decreasing cross-frame spacing were found to reduce lateral flange bending stresses. The values of lateral flange bending stress for all configurations were greater than the bounds of the approximate values suggested by AASHTO. Moreover, the minimum values for fl provided in the AASHTO- LRFD Bridge Design Specifications were found to be significantly lower than the results obtained from this study.The Kansas Department of Transportatio

Repair of Distortion-Induced Fatigue Damage in Bridge No. 135-87 (043SB and 044NB) Using Newly-Developed Strengthening Schemes

A steel girder twin bridge structure located near Park City, Kansas has experienced extensive distortion-induced fatigue cracking in its web gap regions. Due to the bridge’s skewed, staggered configuration, the majority of these cracks have occurred in the bottom web gap region. The bridge was previously the subject of a series of detailed finite element analyses that investigated the effectiveness of several types of retrofits in repairing its distortion-induced fatigue cracks. One of these retrofits, the “angles-with-plate” retrofit, was developed and tested at the University of Kansas as a new retrofitting technique aimed at providing a more economical and easy-to-install distortion-induced fatigue cracking repair. The retrofit is made up of a pair of angles and a backing plate that connect the cross frame connection plate and girder web in order to stiffen the web gap region. Results from the finite element analyses determined that the angles-with-plate retrofit was the most effective and economical choice for repairs in the bridge, and plans were made for its installation. To investigate the performance of the angles-with-plate retrofit, two field tests were performed that monitored behavior of the bridge both before and after the retrofit was installed. Results from these field tests were compared with results from complementary finite element analyses to determine the overall effectiveness of the retrofit. In the bottom web gap region, where cracking is most prevalent in the bridge, the angles-with-plate retrofit was successful at lowering stress demands that would lead to crack propagation. The same conclusion could not clearly be made for all cases in the bridge’s less problematic top web gap region, so a secondary set of finite element analyses was performed to gain a better understanding of what was happening in that region. Further analyses of the two common types of distortion-induced fatigue cracking determined that, while not always large, the angles-with-plate retrofit was successful in reducing stress demands in the top web gap region. Therefore, it was concluded that the angles-with-plate retrofit was an effective repair for the problematic bottom web gap regions of the bridge, and if needed, can be used effectively in the less demanding top web gap region.The Kansas Department of Transportatio

Improving Infrastructure Sustainability II: Repairing Existing Fatigue Cracks in Steel Bridges Using CFRP Materials

Distortion-induced fatigue affects a large number of bridges of the US highway system. This type of damage is commonly observed at connections between cross-frames and steel girders. The differential displacement induced by bridge traffic induces forces in the cross frames that cause out-of-plane distortion of the web, inducing highly localized stresses at the welds that tie the connection plate used to attach the cross frame to the girder. This report describes the results of an experimental program to evaluate the use of composite materials to prevent and repair distortion-induced fatigue damage in web-gap regions of steel girders. In this method of repair, a composite block is cast in place in the area surrounding the cross-frame to girder connection to provide an alternate load path and reduce the stress demands in the welds of the connection. Two full-depth bridge girders were subjected to dynamic loading under a constant force range and allowed to develop fatigue cracks. The girders were subsequently repaired using composite blocks and subjected to several million fatigue cycles. Test results showed that the repair method was effective in halting the propagation of fatigue cracks in the bridge girders, and that it was particularly effective when anchor bolts were attached to the girder flange. The main body of the report focuses on the experimental study, while additional details regarding computational simulations of the composite block and fabrication techniques are provided in Appendices A and B.The Kansas Department of Transportatio

Improving Infrastructure Sustainability I: Extending Useable Lives of Steel Bridges by Halting Distortion-Induced Fatigue Crack Propagation Using Pretensioned Bolts and Plate Washers

Drilling crack-arrest holes to halt fatigue crack propagation is a simple technique that is commonly used by bridge owners controlling and/or repairing fatigue cracking in steel bridges. Well-established relationships exist for sizing the diameter of the crack-arrest holes for in-plane fatigue loading; however, the effectiveness of crack-arrest holes under out-of-plane (distortion-induced) fatigue is not well-understood. Distortion-induced fatigue cracking is much more common in steel bridge infrastructure than in-plane fatigue cracking, and bridge owners often utilize drilled crack-arrest holes in these cases as a “first response” against fatigue cracks discovered during inspections. The purpose of the crack-arrest hole is to smooth out the sharp crack tip, reducing the stress concentration and halting/delaying crack propagation. Common knowledge has been that large diameter crack- arrest holes are more effective at halting crack propagation under distortion-induced fatigue than small diameter crack arrest holes. However, drilling large diameter crack-arrest holes can have strength implications for a structure, and may not be desirable. Additionally, there is little evidence in the literature that large diameter crack-arrest holes perform better than small diameter crack-arrest holes under distortion-induced fatigue. A study examining the effectiveness of crack-arrest holes of varying diameters under distortion-induced fatigue loading was performed. The investigation was comprised of both experimental and analytical components. The experimental study was performed on segments of plate girder loaded under distortion-induced fatigue. Crack-arrest holes of various diameters were drilled at the tips of the cracks of different lengths, and their effectiveness were evaluated. A suite of three-dimensional, solid-element finite element analyses was also used to parametrically vary crack-arrest hole diameter, placement, and crack length. The study also included an analytical examination of using pretensioned bolts and plate washers in a crack-arrest hole. Limited effectiveness was noted for this technique, so the majority of the research focused on appropriate crack-arrest hole sizing and placement. The findings from the experimental and analytical components of this study were compared against common industry practices. The results show that crack-arrest hole placement, rather than hole diameter, has a much greater effect on the effectiveness of the crack arrest hole in bridge girders susceptible to distortion-induced fatigue.The Kansas Department of Transportatio

Editorial : Recent advances in the ecology and evolution of the Bathyergidae

No abstract available.http://frontiersin.org/Ecology_and_Evolutiondm2022Zoology and Entomolog

Directly interrogating single quantum dot labelled UvrA2 molecules on DNA tightropes using an optically trapped nanoprobe

AbstractIn this study we describe a new methodology to physically probe individual complexes formed between proteins and DNA. By combining nanoscale, high speed physical force measurement with sensitive fluorescence imaging we investigate the complex formed between the prokaryotic DNA repair protein UvrA2 and DNA. This approach uses a triangular, optically-trapped “nanoprobe” with a nanometer scale tip protruding from one vertex. By scanning this tip along a single DNA strand suspended between surface-bound micron-scale beads, quantum-dot tagged UvrA2 molecules bound to these ‘”DNA tightropes” can be mechanically interrogated. Encounters with UvrA2 led to deflections of the whole nanoprobe structure, which were converted to resistive force. A force histogram from all 144 detected interactions generated a bimodal distribution centered on 2.6 and 8.1 pN, possibly reflecting the asymmetry of UvrA2’s binding to DNA. These observations successfully demonstrate the use of a highly controllable purpose-designed and built synthetic nanoprobe combined with fluorescence imaging to study protein-DNA interactions at the single molecule level.</jats:p

First report on National Health Priority Areas 1996

Focuses on the health of Australians by documenting progress towards goals and targets for the five priority areas of cardiovascular health, cancer control, injury prevention and control, mental health, and diabetes mellitus

Speculating with Voyant: Designs for Data Walls

In recent years, there has been an explosion of data. One approach to big data is visualization. Data can be transformed in aesthetic ways to reveal its truths and to make it appear accessible to humans. What often gets ignored in visualization is the context of consumption of visualizations. Increasingly visualizations are showing up on data walls in public spaces. The scale of data walls and the types of spaces where they are installed change the interpretation and rhetorical affordances of visualization, and that is what this paper is about: exploring the new visual space of data walls through speculative design prototypes

1935 The Freshman, vol. 2, no. 13

The Freshman was a weekly, student newsletter issued on Mondays throughout the academic year. The newsletter included calendar notices, coverage of campus social events, lectures, and athletic teams. The intent of the publication was to create unity, a sense of community, and class spirit among first year students. The front page of issue 13 is dedicated in memoriam of Emile J. Dawson (1910-1932), who died from a cerebral hemorrhage after he struck his head on a concrete floor at the Armory, knocked down by his opponent in an intramural boxing tournament