Collective Chord Behavior in Large Flexible Diaphragms

The seismic behavior of large low-rise buildings with rigid walls and flexible diaphragms will be dominated more by the diaphragm’s seismic response than by the very stiff vertical walls. For practitioners, estimating the stiffness of large flexible diaphragms is important for computing building setbacks from property lines and adjacent structures as well as evaluating structural integrity under seismic loads. In addition, researchers attempting to accurately model a building’s dynamic behavior need to assemble an accurate diaphragm stiffness prediction. The traditional diaphragm chord model consists of a single continuous line of axial resistance at the diaphragm boundaries; however, as this paper will demonstrate a collective series of structural members distributed across the diaphragm will function intentionally or unintentionally as a collective chord, adding significant flexural stiffness and reducing chord forces. In seismically active areas, masonry and concrete wall anchorage forces utilize code-mandated continuous cross-ties within the diaphragm, and often these cross-ties are sufficiently strong and stiff to unintentionally develop collective chord behavior whether in steel or in wood diaphragm systems. While neglecting this embedded collective chord behavior results in conservative chord and diaphragm drift designs, researchers or practitioners trying to predict seismic response of these buildings will potentially underestimate the true seismic response

Control moment gyro optimization study

Control moment gyro optimizatio

A theory-based approach to understanding condom errors and problems reported by men attending an STI clinic

The official published version can be accessed from the link below - Copyright @ 2008 Springer VerlagWe employed the information–motivation–behavioral skills (IMB) model to guide an investigation of correlates for correct condom use among 278 adult (18–35 years old) male clients attending a sexually transmitted infection (STI) clinic. An anonymous questionnaire aided by a CD-recording of the questions was administered. Linear Structural Relations Program was used to conduct path analyses of the hypothesized IMB model. Parameter estimates showed that while information did not directly affect behavioral skills, it did have a direct (negative) effect on condom use errors. Motivation had a significant direct (positive) effect on behavioral skills and a significant indirect (positive) effect on condom use errors through behavioral skills. Behavioral skills had a direct (negative) effect on condom use errors. Among men attending a public STI clinic, these findings suggest brief, clinic-based, safer sex programs for men who have sex with women should incorporate activities to convey correct condom use information, instill motivation to use condoms correctly, and directly enhance men’s behavioral skills for correct use of condoms