当前位置:考试网  > 试卷库  > 学历类  > 自考  > 自考专业(建筑工程)  > 混凝土及砌体结构  > 简述受弯构件正截面的三种破坏形态。
试题预览

简述受弯构件正截面的三种破坏形态。

查看答案
收藏
纠错
正确答案:

适筋:当受拉区配置适量的钢筋时,受拉钢筋首先到达屈服强度而引起破坏,破坏时有明显的预兆,为“塑性破坏”。钢筋和混凝土基本上都得到充分利用。

超筋:当受拉区配置的钢筋过多时,受压区混凝土首先被压碎而引起破坏,钢筋拉应力尚小于屈服强度,破坏前没有明显的预兆,为“脆性破坏”。

少筋:当配筋量很低,构件破坏前的极限弯矩Mu不大于开裂时的弯矩Mcr;构件混凝土一开裂,受拉钢筋立即屈服,受压区混凝土进入强化阶段产生破坏。构件开裂后立即发生很宽的裂缝和很大的挠度,也属于“脆性破坏”。

答案解析:

暂无解析

你可能感兴趣的试题

在以下单层厂房结构的各构件中,不属于主要受力构件的有()

对结构进行设计时的荷载组合包括()、标准组合、频遇组合、和准永久组合。

下面说法正确的是()

先张法和后张法预应力混凝土构件,其传递预应力方法的区别是()

影响裂缝宽度的主要因素是()

热门试题 更多>
某市建筑公司承建的供毛公司职工培训楼工程,地下一层;地上十二层,建筑面积24000m2,钢筋混凝土框架结构,计划竣工日期为2006 年 8 月 8 日。2000 年 4 月 28 日,市建委有关经管部门按照《建筑施工安全检查规范》〔JGJ59-99〕等有关规定对本工程进行了安全质量大检查。检查人员在询问工程经理有关安全职责履行情况时,工程经理认为他已配备了专职安全员,而且给予其经济奖罚等权力,他已经尽到了安全经管责任,安全搞得好坏那是专职安全员的事;在对专职安全员进行考核时,当问到《安经管检查评分表》检查工程的保证工程有哪几项时,安全员只说到了“目标经管”、‘施工组织设计” 两项; 检查组人员在质量检查时,还发现第二层某柱下部混凝土表面存在较严重的“蜂窝”现象。检查结束后检查组进行了讲评,并宣布部分检查结果如下: (1)该工程《文明施工检查评分表》、《“三宝”、“四口”防护检查评分表》 、《施工机具检查评分表》等分项检查评分表(按百分制)实得分分别为80 分、 85 分和 80 分(以上分项中的满分在汇总表中分别占20 分、10 分和 5 分);(2)《起重吊装安全检查评分表》实得分为0 分;( 3)汇总表得分值为79 分。 问题: 1.工程经理对自己应负的安全经管责任的认识全面吗?说明理由。 2.专职安全员关于《安全经管检查评分表》中保证工程的回答还应包括哪几项? 3.该工程的混凝土表面的“蜂窝”现象应该知何处理? 4.根据各分项检查评分换算成汇总表中相应分项的实得分。 5.本工程安全生产评价的结果属于哪个等级?说明理由。
试题分类: 一级建造师
练习次数:0次
We can begin our discussion of “population as global issue” with what most persons mean when they discuss “the population problem”: too many people on earth and a too rapid increase in the number added each year. The facts are not in dispute, It was quite right to employ the analogy that likened demographic growth to “a long, thin powder fuse that burns steadily and haltingly until it finally reaches the charge and explodes.” To understand the current situation, which is characterized by rapid increases in population, it is necessary to understand the history of population trends. Rapid growth is a comparatively recent phenomenon. Looking back at the 8,000 years of demographic history, we find that populations have been virtually stable or growing very slightly for most of human history. For most of our ancestors, life was hard, often nasty, and very short. There was high fertility in most places, but this was usually balanced by high mortality. For most of human history, it was seldom the case that one in ten persons would live past forty, while infancy and childhood were especially risky periods. Often, societies were in clear danger of extinction because death rates could exceed their birthrates. Thus, the population problem throughout most of history was how to prevent extinction of the human race. This pattern is important to notice. Not only does it put the current problems of demographic growth into a historical perspective, but it suggests that the cause of rapid increase in population in recent years is not a sudden enthusiasm for more children, but an improvement in the conditions that traditionally have caused high mortality. Demographic history can be divided into two major periods: a time of long, slow growth which extended from about 8,000 BC.till approximately AD. 1650. In the first period of some 9600 years, the population increased from some 8 million to 500 million in 1650. Between 1650 and the present, the population has increased from 500 million to more than 4 billion. And it is estimated that by the year 2000 there will be 6.2 billion people throughout the world. One way to appreciate this dramatic difference in such abstract numbers is to reduce the time frame to something that is more manageable. Between 8000BC and 1650, an average of only 50,000 persons was being added annually to the world’s population each year. At present, this number is added every six hours. The increase is about 80,000,000 persons annually. 1.Which of the following demographic growth pattern is most suitable for the long thin powder fuse analogy? A.A virtually stable or slightly decreasing period and then a sudden explosion of population. B.A slow growth for a long time and then a period of rapid, dramatic increase. C.Too many people on earth and a few rapid increase in the number added each year. D.A long period when death rates exceeds birthrates and then a short period with higher fertility and lower mortality. 2.During the first period of demographic history, societies were often in danger of extinction because___. A.only one in ten persons could live past 40. B.there was higher mortality than fertility in most places. C.it was too dangerous to have babies due to the poor conditions. D.our ancestors had little enthusiasm for more children. 3.Which statement is true about population increase? A.There might be an increase of 2.2 billion persons from now to the year 2000. B.About 50,000 babies are born every six hours at present. C.Between 8000 BC and the present, the population increase is about 80,000,000 persons each year. D.The population increased faster between 8000BC and 1650 than between 1650 and the present. 4.The author of the passage intends to___. A.warn people against the population explosion in the near future. B.compare the demographic growth pattern in the past with that after 1650. C.find out the cause for rapid increase in population in recent years. D.present us a clear and complete picture of the demographic growth. 5.The word “demographic” in the first paragraph means___. A.statistics of human. B.surroundings study. C.accumulation of human. D.development of human.
试题分类: 大学英语六级
练习次数:3次
试题分类: 安全员
练习次数:1次
Recent research has claimed that an excess of positive ions in the air can have an ill effect on people’s physical or psychological health. What are positive ions? Well, the air is full of ions, electrically charged particles, and generally there is a rough balance between the positive and the negative charged. But sometimes this balance becomes disturbed and a larger proportion of positive ions are found. This happens naturally before thunderstorm, earthquakes when winds such as the Mistral, Hamsin or Sharav are blowing in certain countries. Or it can be caused by a build-up of static electricity indoors from carpets or clothing made of man-made fibres, or from TV sets, duplicators or computer display screens. When a large number of positive ions are present in the air many people experience unpleasant effects such as headaches, fatigue, irritability, and some sensitive people suffer nausea or even mental disturbance. Animals are also affected, particularly before earthquakes, snakes have been observed to come out of hibernation, rats to flee from their burrows, dogs howl and cats jump about unaccountably. This has led the US Geographical Survey to fund a network of volunteers to watch animals in an effort to foresee such disasters before they hit vulnerable areas such as California. Conversely, when large numbers of negative ions are present, then people have a feeling of well-being. Natural conditions that produce these large amounts are near the sea, close to waterfalls or fountains, or in any place where water is sprayed, or forms a spray. This probably accounts for the beneficial effect of a holiday by the sea, or in the mountains with tumbling streams or waterfalls. To increase the supply of negative ions indoors, some scientists recommend the use of ionisers: small portable machines, which generate negative ions. They claim that ionisers not only clean and refresh the air but also improve the health of people sensitive to excess positive ions. Of course, there are the detractors, other scientists, who dismiss such claims and are skeptical about negative/positive ion research. Therefore people can only make up their own minds by observing the effects on themselves, or on others, of a negative rich or poor environment. After all it is debatable whether depending on seismic readings to anticipate earthquakes is more effective than watching the cat. 1.What effect does exceeding positive ionization have on some people? A.They think they are insane. B.They feel rather bad-tempered and short-fussed. C.They become violently sick. D.They are too tired to do anything. 2.In accordance with the passage, static electricity can be caused by___. A.using home-made electrical goods. B.wearing clothes made of natural materials. C.walking on artificial floor coverings. D.copying TV programs on a computer. 3.A high negative ion count is likely to be found___. A.near a pound with a water pump. B.close to a slow-flowing river. C.high in some barren mountains. D.by a rotating water sprinkler. 4.What kind of machine can generate negative ions indoors? A.Ionisers. B.Air-conditioners. C.Exhaust-fans D.Vacuum pumps. 5.Some scientists believe that___. A.watching animals to anticipate earthquakes is more effective than depending on seismography. B.the unusual behavior of animals cannot be trusted. C.neither watching nor using seismographs is reliable. D.earthquake
试题分类: 大学英语六级
练习次数:2次
背景资料: 某建设单位新建一工业项目,经招标, 机电工程由具备机电工程总承包一级资格的A 安装工程公司总承包。 其中,车间内的消防工程、锅炉房工程、变电所工程由建设单位直接发包给具有专业资质的B公司。合同规定,施工现场管理由 A公司总负责,工程项目主材由A 公司提供,工程设备由建设单位指定厂家,A 公司负责采购并与制造厂商签订合同。 A、B 两个公司都分别组建了项目部。在施工过程中,发生如下事件: 事件 1:监理公司发现B公司在锅炉安装施工前,没有办理书面告知手续就进行施工,施工作业人员没有持证上岗,便指令 B 公司停工。 事件 2:由于 A 公司采购的变压器延期一个月到现场,致使B 公司发生窝工和停工,造成经济损失,B 公司向 A公司提出索赔。 事件 3:A公司在跟制造商签订采购合同以后,积极督促制造商,并且经常与之协调,保证了设备的按时供应。 事件 4:消防工程验收时,B施工单位提交的有关验收技术资料不完整,公安消防监督机构不予验收。消防工程竣工后,建设单位向公安消防监督机构提交工程消防验收申请,填写了《建筑工程消防验收申报表》,要求公安消防监督机构进行消防验收并投入使用,但公安消防监督机构不受理。 问题: 1. 在事件 1 中,说明监理公司指令B公司停工的理由。锅炉安装工程应配备哪些主要的特种作业人员? 2. 在事件 2 中, B 公司向 A 公司提出索赔,是否合理?说明理由。 3. 在事件 3 中, A 公司与供货商协调了哪些方面的问题? 4. 通过事件 4,说明消防工程验收的条件。
试题分类: 安全员
练习次数:0次
Passage 2 Questions 6 to 10 are based on the following passage: In order to learn to be one’s true self, it is necessary to obtain a wide and extensive knowledge of what has been said and done in the world; critically to inquire into it; carefully to consider it; clearly to analyze it; and earnestly to carry it out. It matters not what you learn, but when you once learn a thing, you must never give it up until you have mastered it. It matters not what you inquire into, but when you once inquire into a thing, you must never give it up until you have thoroughly understood it. It matters not what you try to think out, but when you once try to think out a thing, you must never give it up until you have got what you want. It matters not what you try to carry out, but when you once carry out a thing, you must never give it up until you have don’t it thoroughly and well. If another man succeeds by one effort, you will use a hundred efforts. If another man succeeds by ten efforts, you will use a thousand. 6. According to the author, first of all one must . A. analyze B. inquire C. obtain knowledge D. act 7. According to the author, . A. learning is not important B. thinking is not necessary C. knowledge means little D. it is not important what we learn 8. The end of learning should be . A. thought B. mastery C. inquiry D. analysis 9. According to the author, another man’s success should . A. make greater efforts B. make us nervous C. not be taken into consideration D. cause one to stop trying 10. The author implies but does not say what . A. the way to knowledge is through specialization B. one has to know everything to be successful C. success depends not so much on natural ability as it does on effort D. success in one’s profession is latest important in one’s life
试题分类: 大学英语四级
练习次数:16次
扫一扫,手机做题