Assessment of ASCE 7-10 for wind effects on low-rise wood frame buildings with database-assisted design methodology

Jing He,Fang Pan,C.S. Cai 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.3

The design wind pressure for low-rise buildings in the ASCE 7-10 is defined by procedures that are categorized into the Main Wind Force-Resisting System (MWFRS) and the Components and Cladding (C&C). Some of these procedures were originally developed based on steel portal frames of industrial buildings, while the residential structures are a completely different structural system, most of which are designed as low-rise light-frame wood constructions. The purpose of this study is to discuss the rationality (or irrationality) of the extension of the wind loads calculated by the ASCE 7-10 to the light-frame wood residential buildings that represent the most vulnerable structures under extreme wind conditions. To serve this purpose, the same approach as used in the development of Chapter 28 of the ASCE 7-10 that envelops peak responses is adopted in the present study. Database-assisted design (DAD) methodology is used by applying the dynamic wind loads from Louisiana State University (LSU) database on a typical residential building model to assess the applicability of the standard by comparing the induced responses. Rather than the postulated critical member demands on the industrial building such as the bending moments at the knee, the maximum values at the critical points for wood frame buildings under wind loads are used as indicators for the comparison. Then, the critical members are identified through these indicators in terms of the displacement or the uplift force at connections and roof envelope. As a result, some situations for each of the ASCE 7 procedures yielding unconservative wind loads on the typical low-rise residential building are identified.

Assessment of ASCE 7-10 for wind effects on low-rise wood frame buildings with database-assisted design methodology

He, Jing,Pan, Fang,Cai, C.S. Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.27 No.3

The design wind pressure for low-rise buildings in the ASCE 7-10 is defined by procedures that are categorized into the Main Wind Force-Resisting System (MWFRS) and the Components and Cladding (C&C). Some of these procedures were originally developed based on steel portal frames of industrial buildings, while the residential structures are a completely different structural system, most of which are designed as low-rise light-frame wood constructions. The purpose of this study is to discuss the rationality (or irrationality) of the extension of the wind loads calculated by the ASCE 7-10 to the light-frame wood residential buildings that represent the most vulnerable structures under extreme wind conditions. To serve this purpose, the same approach as used in the development of Chapter 28 of the ASCE 7-10 that envelops peak responses is adopted in the present study. Database-assisted design (DAD) methodology is used by applying the dynamic wind loads from Louisiana State University (LSU) database on a typical residential building model to assess the applicability of the standard by comparing the induced responses. Rather than the postulated critical member demands on the industrial building such as the bending moments at the knee, the maximum values at the critical points for wood frame buildings under wind loads are used as indicators for the comparison. Then, the critical members are identified through these indicators in terms of the displacement or the uplift force at connections and roof envelope. As a result, some situations for each of the ASCE 7 procedures yielding unconservative wind loads on the typical low-rise residential building are identified.

A coupled wind-vehicle-bridge system and its applications: a review

Cai, C.S.,Hu, Jiexuan,Chen, Suren,Han, Yan,Zhang, Wei,Kong, Xuan Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

The performance of bridges under strong wind and traffic is of great importance to set the traveling speed limit or to make operational decisions for severe weather, such as controlling traffic or even closing the bridge. Meanwhile, the vehicle's safety is highly concerned when it is running on bridges or highways under strong wind. During the past two decades, researchers have made significant contributions to the simulation of the wind-vehicle-bridge system and their interactive effects. This paper aims to provide a comprehensive review of the overall performance of the bridge and traffic system under strong wind, including bridge structures and vehicles, and the associated mitigation efforts.

A coupled wind-vehicle-bridge system and its applications: a review

C.S. Cai,Jiexuan Hu,Suren Chen,Yan Han,Wei Zhang,Xuan Kong 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

The performance of bridges under strong wind and traffic is of great importance to set thetraveling speed limit or to make operational decisions for severe weather, such as controlling traffic or evenclosing the bridge. Meanwhile, the vehicle‟s safety is highly concerned when it is running on bridges orhighways under strong wind. During the past two decades, researchers have made significant contributionsto the simulation of the wind-vehicle-bridge system and their interactive effects. This paper aims to providea comprehensive review of the overall performance of the bridge and traffic system under strong wind,including bridge structures and vehicles, and the associated mitigation efforts.

Activated Microglia Are Less Vulnerable to Hemin Toxicity due to Nitric Oxide-Dependent Inhibition of JNK and p38 MAPK Activation

Cai, Y.,Cho, G.-S.,Ju, C.,Wang, S.-L.,Ryu, J.H.,Shin, C.Y.,Kim, H.-S.,Nam, K.-W.,Jalin, A.M.A.A.,Sun, W. American Association of Immunologists 2011 JOURNAL OF IMMUNOLOGY Vol.187 No.3

Design strategy of hybrid stay cable system using CFRP and steel materials

C.S. Cai,Wen Xiong,Rucheng Xiao,Yin Zhang 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.13 No.1

To enhance cable stiffness, this paper proposed a combined application of carbon fiber reinforced polymers (CFRP) and steel materials, resulting in a novel type of hybrid stay cable system especially for the cable-stayed bridges with main span lengths of 1400~2800 m. In this combination, CFRP materials can conserve all their advantages such as light weight and high strength; while steel materials help increase the equivalent stiffness to compensate for the low elastic modulus of CFRP materials. An increase of the equivalent stiffness of the hybrid stay cable system could be further obtained with a reasonable increase of its safety factor. Following this concept, a series of parametric studies for the hybrid stay cable system with the consideration of stiffness and cost were carried out. Three design strategies/criteria, namely, best equivalent stiffness with a given safety factor, highest ratio of equivalent stiffness to material cost with a given safety factor, and best equivalent stiffness under a given cost were proposed from the stiffness and cost viewpoints. Finally, a comprehensive design procedure following the proposed design strategies was suggested. It was shown that the proposed hybrid stay cable system could be a good alternative to the pure CFRP or traditional steel stay cables in the future applications of super long span bridges.

Optimal variables of TMDs for multi-mode buffeting control of long-span bridges

Chen, S.R.,Cai, C.S.,Gu, M.,Chang, C.C. Techno-Press 2003 Wind and Structures, An International Journal (WAS Vol.6 No.5

In the past decades, much effort has been made towards the study of single-mode-based vibration controls with dynamic energy absorbers such as single or multiple Tuned Mass Dampers(TMDs). With the increase of bridge span length and the tendency of the bridge cross-section being more slender and streamlined, multi-mode coupled vibrations as well as their controls have become very important for large bridges susceptible to strong winds. As a simple but effective device, the TMD system especially the semi-active one has become a promising option for such coupled vibration controls. However, despite various studies of optimal controls of single-mode-based vibrations with TMDs, research on the corresponding controls of the multi-mode coupled vibrations is very rare so far. For the development of a semi-active control strategy to suppress the multi-mode coupled vibrations, a comprehensive parametric analysis on the optimal variables of this control is substantial. In the present study, a multi-mode control strategy named "three-row" TMD system is discussed and the general numerical equations are developed at first. Then a parametric study on the optimal control variables for the "three-row" TMD system is conducted for a prototype Humen Suspension Bridge, through which some useful information and a better understanding of the optimal control variables to suppress the coupled vibrations are obtained. This information lays a foundation for the design of semi-active control.

Re-assessing the enhanced permeability and retention effect in peripheral arterial disease using radiolabeled long circulating nanoparticles

England, C.G.,Im, H.J.,Feng, L.,Chen, F.,Graves, S.A.,Hernandez, R.,Orbay, H.,Xu, C.,Cho, S.Y.,Nickles, R.J.,Liu, Z.,Lee, D.S.,Cai, W. IPC Science and Technology Press 2016 Biomaterials Vol.100 No.-

<P>As peripheral arterial disease (PAD) results in muscle ischemia and neovascularization, it has been claimed that nanoparticles can passively accumulate in ischemic tissues through the enhanced permeability and retention (EPR) effect. At this time, a quantitative evaluation of the passive targeting capabilities of nanoparticles has not been reported in PAD. Using a murine model of hindlimb ischemia, we quantitatively assessed the passive targeting capabilities of Cu-64-labeled PEGylated reduced graphene oxide iron oxide nanoparticles (Cu-64-RGO-IONP-PEG) through the EPR effect using positron emission tomography (PET) imaging. Serial laser Doppler imaging was performed to monitor changes in blood perfusion upon surgical induction of ischemia. Nanoparticle accumulation was assessed at 3, 10, and 17 days post-surgery and found to be highest at 3 days post-surgery, with the ischemic hindlimb displaying an accumulation of 14.7 +/- 0.5% injected dose per gram (%ID/g). Accumulation of Cu-64-RGO-IONP-PEG was lowest at 17 days post-surgery, with the ischemic hindlimb displaying only 5.1 +/- 0.5%ID/g. Furthermore, nanoparticle accumulation was confirmed by photoacoustic imaging (PA). The combination of PET and serial Doppler imaging showed that nanoparticle accumulation in the ischemic hindlimb negatively correlated with blood perfusion. Thus, we quantitatively confirmed that Cu-64-RGO-IONP-PEG passively accumulated in ischemic tissue via the EPR effect, which is reduced as the perfusion normalizes. As Cu-64-RGO-IONP-PEG displayed substantial accumulation in the ischemic tissue, this nanoparticle platform may function as a future theranostic agent, providing both imaging and therapeutic applications. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Association analyses of East Asian individuals and trans-ancestry analyses with European individuals reveal new loci associated with cholesterol and triglyceride levels

Spracklen, C. N.,Chen, P.,Kim, Y. J.,Wang, X.,Cai, H.,Li, S.,Long, J.,Wu, Y.,Wang, Y. X.,Takeuchi, F. IRL Press 2017 Human molecular genetics Vol.26 No.9

<P>Large-scale meta-analyses of genome-wide association studies (GWAS) have identified > 175 loci associated with fasting cholesterol levels, including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). With differences in linkage disequilibrium (LD) structure and allele frequencies between ancestry groups, studies in additional large samples may detect new associations. We conducted staged GWAS meta-analyses in up to 69,414 East Asian individuals from 24 studies with participants from Japan, the Philippines, Korea, China, Singapore, and Taiwan. These meta-analyses identified (P < 5 x 10(-8)) three novel loci associated with HDL-C near CD163-APOBEC1 (P = 7.4 x 10(-9)), NCOA2 (P = 1.6 x 10(-8)), and NID2-PTGDR (P = 4.2 x 10(-8)), and one novel locus associated with TG near WDR11-FGFR2 (P = 2.7 x 10(-10)). Conditional analyses identified a second signal near CD163-APOBEC1. We then combined results from the East Asian meta-analysis with association results from up to 187,365 European individuals from the Global Lipids Genetics Consortium in a trans-ancestry meta-analysis. This analysis identified (log(10)Bayes Factor a 6.1) eight additional novel lipid loci. Among the twelve total loci identified, the index variants at eight loci have demonstrated at least nominal significance with other metabolic traits in prior studies, and two loci exhibited coincident eQTLs (P < 1 x 10(-5)) in subcutaneous adipose tissue for BPTF and PDGFC. Taken together, these analyses identified multiple novel lipid loci, providing new potential therapeutic targets.</P>

Electrochromism in indium-tin-oxide films for laser-writing application

Mane, R.S.,Cai, G.,Hoeil, C.,Lokhande, C.D.,Han, S.-H. North-Holland 2009 Physica E, Low-dimensional systems & nanostructure Vol.41 No.7

We report for the first time laser-writing application on an electrochemically NH<SUB>4</SUB><SUP>+</SUP> ion intercalated indium-tin oxide (ITO). NH<SUB>4</SUB><SUP>+</SUP> ion intercalation results into a color change from transparent to brown with a significant enhancement of the surface roughness. Both bare and intercalated ITO's are explored for their structural, surface morphological, and wettability studies. Upon NH<SUB>4</SUB><SUP>+</SUP> intercalation, both an optical absorbance and the surface wettability of ITO changes substantially. A micrometer-scale laser-writing application on intercalated ITO film is achieved after exposing an Ar-ion laser that is non-erasable even after a period of six months. This idea can be used for maintaining long-term safe secrete data.