Numerical Investigation of Composite Floor Beam Resilience to Realistic Fire Scenarios

This thesis provides a computational investigation of three separate composite steelbeam fire tests conducted at Lehigh University’s ATLSS Laboratory as well as parametricanalyses with various fire curves and levels of passive protection. The objective of thisstudy was to validate numerical models that conservatively capture structural failure ofcomposite floors subjected to fire, while striving for simplicity, to help further realizeperformance-based design and evaluation approaches for structural-fire resistance andresilience of secondary floor framing in steel buildings.The first pair of tests were identical structural systems with one having passive fireprotection and the other being unprotected subjected to the ASTM E119 fire curve.Thermal analysis of the steel was performed using a lumped mass approach, which can beimplemented via spreadsheet or a simple, explicit programmed solution. Thermal analysisof the slab was performed using a simple one-dimensional heat flow model. Two types offinite element analyses were performed: one composed of shell elements and anothercomposed of fiber-beam elements. The slab was unrestrained in all cases, so the effects ofslab continuity and membrane action were neglected. The structural models referencedboth lumped mass prediction temperatures as well as measured test temperatures as inputfor the temperature-dependent material properties of the specimens. The results of allmodels show conservative agreement with the experimentally observed behavior. Theplasticity of the section is analyzed over the duration of the tests using the concept ofwarping axial-moment failure envelopes which consider shifting of the effective centroiddue to the thermal gradient per three-sided heating. These models can be leveraged as part of a conservative performance-based approach to design composite floor assemblies forone-way flexural behavior under fire.The final validation case consisted of an unprotected composite beam subjected toa realistic fire curve with a decay phase. The objective of this study was to point towardsthe possibility of surviving a realistic fire scenario with a decay phase, as opposed to thecontinued growth of the ASTM E119 curve. The test fire curve closely matches the E119fire for 20 minutes prior to rapidly decaying. The test beam was shown to withstand theparametric fire curve computationally, resulting in relatively little damage, matching thetest observations reported. According to the ASTM E119 thermal criteria, the beam“failed” around 13 minutes. The same pair of SAFIR finite element models used in therunaway failure model validation were used to compare structural behavior of an assemblywhen it is permitted to cool in the case of fire suppression.The models of the realistic fire test were then parametrically extended to variouscombinations of active and passive protection, as well as different fire curve formulations.The fact that these models could capture failure per the first validation study allowed forthis extension to be confidently applied. The model comparisons highlight the current E119standard‘s lack of resiliency quantification. The standard may have potential to be used asa benchmarking tool in resiliency calculations, in turn making use of the plethora of datathat has already been obtained over the last several decades

Contrasting the capabilities of building energy performance simulation programs

For the past 50 years, a wide variety of building energy simulation programs have been developed, enhanced and are in use throughout the building energy community. This paper is an overview of a report, which provides up-to-date comparison of the features and capabilities of twenty major building energy simulation programs. The comparison is based on information provided by the program developers in the following categories: general modeling features; zone loads; building envelope and daylighting and solar; infiltration, ventilation and multizone airflow; renewable energy systems; electrical systems and equipment; HVAC systems; HVAC equipment; environmental emissions; economic evaluation; climate data availability, results reporting; validation; and user interface, links to other programs, and availability

CXCL12 Chemokine Expression and Secretion Regulates Colorectal Carcinoma Cell Anoikis through Bim-Mediated Intrinsic Apoptosis

BACKGROUND: Resistance to anoikis, apoptosis triggered by a loss of cellular adhesion to the underlying extracellular matrix, is a hallmark of metastatic cancer. Previously we have shown re-establishment of CXCL12 expression in colorectal carcinoma cells inhibits metastasis by enhancing anoikis sensitivity. The objective of these studies was to define the signaling mechanisms regulating CXCL12-mediated anoikis. METHODOLOGY/PRINCIPAL FINDINGS: Adhesion, examined by crystal violet staining, immunofluorescence microscopy, and immunoblot analysis indicated decreased focal adhesion signaling corresponding with loss of adhesion in cells constitutively simulated by CXCL12. Loss of adhesion was inhibited by pertussis toxin treatment, indicating CXCL12 regulating anoikis through G(αi)-protein coupled receptors. Non-adherent HCT116 and HT29 colorectal carcinoma cells expressing CXCL12 exhibited enhanced anoikis sensitivity by propidium iodide staining, caspase activity assays, and immunoblot compared to GFP control cells. CXCL12 producing carcinomas cultured on poly-HEMA displayed heightened Bim and loss of Mcl-1 and Bcl-2 preceding cytochrome c release, and caspase-9 activation. RNAi knockdown of Bim reversed anoikis sensitivity of CXCL12-expressing cells and fostered increased soft-agar foci formation and hepatic tumors in an orthotopic mouse model of metastasis. CONCLUSIONS/SIGNIFICANCE: These data indicate CXCL12 provides a barrier to metastasis by increasing anoikis via activation of a Bim-mediated intrinsic apoptotic pathway. These results underscore the importance of retaining CXCL12 expression to sensitize colorectal carcinomas to anoikis and minimize tumor progression

Triacylglycerol mobilization is suppressed by brefeldin A in Chlamydomonas reinhardtii

Brefeldin A suppresses vesicle trafficking by inhibiting exchange of GDP for GTP in ADP-ribosylation factor. We report that brefeldin A suppresses mobilization of triacylglycerols in Chlamydomonas reinhardtii, a model organism of green microalgae. Analyses revealed that brefeldin A causes Chlamydomonas to form lipid droplets in which triacylglycerols accumulate in a dose-dependent manner. Pulse labeling experiment using fluorescent fatty acids suggested that brefeldin A inhibits the cells from degrading fatty acids. The experiment also revealed that the cells transiently form novel compartments that accumulate exogenously added fatty acids in the cytoplasm, designated fatty acid-induced microbodies (FAIMs). Brefeldin A up-regulates the formation of FAIMs, whereas nitrogen deprivation that up-regulates triacylglycerol synthesis in Chlamydomonas does not cause the cells to form FAIMs. These results underscore the role of the vesicle trafficking machinery in triacylglycerol metabolism in green microalgae. © 2013 The Author

Risk-taking that signals trust increases social identification

ocial identification predicts many important phenomena; however, its determinants have received comparably little research attention. We argue that people are more likely to socially identify with others who engage in risky behavior that implies trust than with those who act cautiously, and test this in four experiments with over 900 participants. The experiments found support for the hypotheses across diverse risk contexts – specifically, risk of physical injury, disease risk, and financial risk. These findings indicate that others’ risk taking can strengthen shared psychological group membership