潮汐区海水侵蚀混凝土结构加速模拟试验装置

在海水潮汐区,氯盐侵蚀是混凝土结构耐久性能降低的主要因素针对潮汐区的环境特点设计制作了潮汐区海水侵蚀混凝土结构加速模拟试验装置,该装置主要由微电脑时控开关、全自动水位控制器、磁力水泵、水位传感器、试验箱等组成通过微电脑时控开关控制磁力水泵的开始启动时间;水位控制器和水位传感器控制磁力水泵停止工作时间,使2个试验箱中的混凝土试件交替处于浸润和干燥状态来模拟处于潮汐区的混凝土周期性浸润和干燥的过程.利用设计的试验装置进行了潮汐区混凝土氯盐侵蚀加速试验,试验中该装置严格按照设定的时间制度工作.另外,试验装置工作稳定、噪音小,制作成本很低,并可方便地放置在人工气候环境模拟箱中进行不同环境条件下的耐久性试验.     

碳纤维混凝土抗裂性能的试验研究

采用圆环试验法研究了碳纤维体积掺量对混凝土抗裂性的影响,并结合复合材料理论和纤维间距理论对碳纤维的抗裂机理进行了分析探讨.结果显示:碳纤维的掺入能延缓裂缝的出现,有效抑制裂缝的扩展;碳纤维掺量越大,试件开裂越晚,主裂缝宽度越小,试件抗裂性越好;用复合材料理论和纤维间距理论分析碳纤维对混凝土抗裂性的增强作用,得出的结论与试验结果是一致的.     

混凝土结构裂缝成因与防治措施浅析

混凝土裂缝一直严重困扰着混凝土结构工程的质量,在混凝土生产以及施工、养护过程中有针对性地采取预防措施,尽可能采取有效的技术措施控制裂缝,使结构尽量不出现裂缝,或尽量减少裂缝的数量和宽度,特别是避免有害裂缝的出现,以确保工程质量,使建筑物具备良好的耐久性和结构稳定性.     

浅谈混凝土开裂成因及预防措施

近年来,随着我国交通基础建设得到迅猛发展,在施工过程中,混凝土开裂可以说是"常发病"和"多发病",给广大居民带来了极大的不便.混凝土工程施工过程中,经常发生一些裂缝,影响结构的安全,保证工程结构安全,是工程管理人员急需掌握的,为了进一步加强对混凝土裂缝的认识,尽量避免工程中出现危害较大的裂缝,本文对混凝土裂缝的产生的原因作出分析,重点阐述了防止裂缝采取的措施以及裂缝修补方法.     

自密实混凝土受弯梁受力各阶段的裂缝测量试验研究

自密实混凝土是混凝土的一个重要组成部分和未来发展方向,因其良好的工作性能和优越的耐久性而在土木工程各个领域得到越来越多的广泛应用。钢筋混凝土结构受力反应的主要特征是裂缝的产生和发展,受弯梁的裂缝测量对确定结构的开裂荷载,研究结构的抗裂和变形性能及破坏过程都有十分重要的意义。对自密实混凝土受弯梁的裂缝做了一定研究。     

钢筋锈蚀对再生混凝土梁柱节点抗震性能的影响

为研究钢筋锈蚀后再生混凝土框架节点的破坏特征和抗震性能,对钢筋未锈蚀、锈蚀而保护层未开裂、平均锈胀裂缝宽度为0．2mm及平均锈胀裂缝宽度为0．4mm四种情况下的再生混凝土及普通混凝土框架边节点,进行了低周反复荷载对比试验;观察节点的受力过程及破坏形态,分析试件的荷载一位移滞回曲线、承载能力、强度和刚度退化、延性以及耗能能力等力学特性．结果表明：相同锈蚀程度下,再生混凝土节点的强度比普通混凝土节点小,再生混凝土节点的刚度退化比普通混凝土节点严重,再生混凝土节点表现出更好的延性,再生混凝土耗能较普通混凝土耗能弱;随着钢筋锈蚀程度的增加,再生混凝土与普通混凝土节点的强度降低,刚度减小,延性减小,耗能能力降低．     

基于LNG混凝土储罐的预制裂缝混凝土超低温冻融循环试验研究（英文）

为探究液化天然气混凝土储罐泄露工况下混凝土的物理力学特性,采用液氮制冷和浸水融化的方式,开展了混凝土超低温冻融循环试验,分析了超低温、冻融循环、预制裂缝、是否掺加钢纤维等因素对混凝土抗压强度、抗折强度、劈裂抗拉强度的影响.试验结果表明,预制裂缝宽度在冻融循环后呈扩大趋势.当冷冻温度为-80℃时,预制裂缝相对宽度扩大1～2倍;当冷冻温度为-120℃时,预制裂缝相对宽度扩大2～5倍.与未掺加钢纤维的混凝土试件相比,掺有钢纤维的混凝土试件经历力学性能试验后仍能保持较完整的外观结构.混凝土抗压强度、抗折强度、劈裂抗拉强度随冷冻温度降低而减小,掺加钢纤维后则均有所提高.     

浅谈混凝土结构裂缝产生的原因及防治措施

本文分析了混凝土结构裂缝的种类和产生的原因,介绍了防治裂缝的措施和方法.在混凝土结构施工过程中应尽可能地采取有效的技术措施控制裂缝,使结构尽量不出现裂缝,或尽量减少和避免不良裂缝的产生,以确保混凝土工程质量.     

桥梁施工中钢筋混凝土裂缝的成因及防范措施

混凝土是桥梁建设中的主要材料之一,桥梁80％以上的构件均为钢筋混凝土结构。尽管我们已采取各种措施,在各结构施工过程中混凝土产生的裂缝却无所不在。为了尽量避免工程中危害较大的裂缝和控制可克服裂缝的产生,文对桥梁混凝土施工过程中所产生的裂缝成因作了较为深入的分析,以便在施工过程中采取行之有效的控制措施,证混凝土结构的使用功能及安全性能。     

带初始裂缝钢筋与混凝土粘结破坏机理

钢筋与混凝土之间的粘结是保障钢筋混凝土结构实现其建筑功能(安全性、适用性和耐久性)的关键影响因素之一.通过实验室模拟不同工作环境中带有不同初始裂缝宽度、以及不同水灰比铰梁试件,经海水浸泡180 d干湿循环或大气环境180 d等环境作用下,对钢筋与混凝土粘结性能进行研究.本文主要分析钢筋与混凝土之间粘结破坏机理.本文试验研究结果表明:(1)钢筋与混凝土粘结破坏主要表现为混凝土沿纵筋方向劈裂破坏(贯穿劈裂破坏和部分劈裂破坏);(2)带预制裂缝试件钢筋与混凝土粘结受预制裂缝的影响,钢筋与混凝土的粘结应力分布改变,钢筋与混凝土的粘结破坏为部分劈裂破坏;(3)如果试件中的钢筋不能提供足够拉力时,会发生钢筋受拉屈服的破坏而钢筋与混凝土的粘结不破坏.     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

汉字倒说

汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

钱生钱!

我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了     

Social and Cultural Influence on Word Meaning

Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language.     

Inequalities for inscribed simplexes

The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex.