利用加设钢支撑改变单跨框架结构体系的抗震加固效果研究

单跨框架结构大量存在于中小学建筑中,中小学建筑已提高到乙类设防,根据抗震鉴定标准GB50023-2009,框架结构不宜为单跨框架;乙类设防时,不应为单跨框架。单跨框架是一种抗震严重不利体系,缺乏冗余约束,易发生整体倒塌。若从构件加固层次提高建筑的抗震性能,不但造价高、施工复杂,而且效果也不明显。加设支撑是一种改变建筑结构体系的方法,本文结合工程实例,讨论了加设钢支撑后原结构性能变化以及加固过程中应该注意的问题。研究表明,利用支撑改变结构受力体系,可以明显改善结构性能,提高抗震能力

Chlorofullerenes featuring triple sequentially fused pentagons

通讯作者地址: Tan,YZ(通讯作者),Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Coll Chem & Chem Engn, Dept Chem, Xiamen 361005, Peoples R China 电子邮件地址: [email protected], [email protected] triple sequentially fused pentagons (TSFP) motif is one of the basic subunits that could be used for constructing fullerenes, but it violates the isolated pentagon rule (IPR) and has not been found in carbon cages to date. The properties of TSFP-incorporating fullerenes are thus poorly explored both theoretically and experimentally. Reported herein are four chlorinated derivatives of three different fullerene cages, all with the TSFP motif. X-ray crystallographic analyses indicate that the molecular strain inherent to the pentagon adjacency of a TSFP is significantly relieved upon exohedral chlorination, leaving one of the four pentagon fusion sites unsaturated and rendering the present derivatives chiral. This unique reactivity, in stark contrast to that of previously reported non-IPR fullerenes containing double fused pentagons or triple directly fused pentagons, can be rationalized by density functional theory calculations, and are expected to stimulate further studies of these new members of the fullerene family, both theoretically and experimentally.NNSF of China 20525103,20531050,20721001,20423002 20673088 973 Program 2007CB81530

機械鬆弛定量分析模式建立：填充顆粒效應

本報告將報導研究計劃「機械鬆弛定量分析模式建立：填充顆粒效應」研究的成果。採用添加碳黑的天然橡膠為系統。添加碳黑會使橡膠產生物理交連，程度隨碳黑量增加上升，但橡膠的化學交連則沒有顯著變化。使用DMA 量測頻率為1Hz 不同溫度下的機械鬆弛行為，顯示分子運動受到交連點的限制。進一步以Havriliak-Negami(HN)方程式分析機械鬆弛譜，可知碳黑添加越多時，分子運動所需的活化能越高，熵值的變化也越大。其原因可由交連對分子運動及分子鏈構形的影響來加以說明。由HN 方程式參數α及αβ的分析中可發現交連現象主要影響分子鏈間(inter-chain)的運動，因此造成α值的減小。但分子鏈內(intra-chain) 運動則沒有受到很大的影響，因而αβ的變化並沒有一定的趨勢。The effect of carbon black on the dynamic mechanical relaxation of DCP-cured natural rubber utilizing Dynamic Mechanical Analyzer (DMA) was studied in this work. Adding carbon black increased physical cross-links, while the chemical cross-link density basically maintained the same. From the result of DMA, it was clear the molecular motions were influenced by cross-linking. Further analyzing by Havriliak-Negami (HN) equation, it was found that the more the amount of carbon black, the larger activation energy and the change of entropy of molecular motions. This could be explained by the influence of cross-link density on molecular motions and chain conformations. The analysis of parameters, α and β of HN equation, revealed the cross-linking influenced the inter-chain molecular motions obviously, but not the intra-chain ones. Thus, α decreased with the increase of cross-link density. However, the change of αβ did not have a trend