问题 问答题 案例分析题

某公共建筑工程,建筑面积82000m2,地下三层,地上二十层,层高3.8m,钢筋混凝土框架结构。大堂一至三层中空,大堂顶板为钢筋混凝土井字梁结构,某施工总承包单位承担施工任务。

在工程施工过程中,发生了如下事件:

事件一:开工前,地方建设行政主管部门检查项目施工人员三级教育情况,质询项目经理部的教育内容。施工项目负责人回答:“进行了国家和地方安全生产方针、企业安全规章制度、工地安全制度、工程可能存在的不安全因素四项内容的教育”。受到了地方建设行政主管部门的严厉批评。

事件二:施工总承包单位进场后,采购了Ⅱ级钢筋110t,钢筋出厂合格证明资料齐全。施工总承包单位将同一炉罐号的钢筋组批,在监理工程师见证下,取样复试。复试合格后,施工总承包单位在现场采用冷拉方法调直钢筋,冷拉率控制为3%,监理工程师责令施工总承包单位停止钢筋加工工作。

事件三:施工总承包单位根据《建筑施工模板安全技术规范》,编制了《大堂顶板模板工程施工方案》,并绘制了模板及支架示意图,如下所示。监理工程师审查后要求重新绘制。

事件四:拆模后发现梁底的外露面出现麻面、露筋等表面缺陷。监理要求分析原因并提出后续工程的防治措施。

问题:

指出事件二中施工总承包单位做法的不妥之处,分别写出正确做法。

答案

参考答案:

事件二中施工总承包单位做法的不妥之处及正确做法分别如下:

不妥之一:施工总承包单位将同一炉罐号的钢筋组批进行取样复试;

正确做法:按同一厂家、同一牌号、同一规格,将同一进场批次进场的钢筋,按不超过60t为一检验批量进行取样复试。

不妥之二:调直钢筋时,冷拉率控制为3%;

正确做法:调直钢筋时,冷拉率不应超过1%。

解析:

事件二描述了两件事,一是钢筋组批取样复试,二是钢筋冷拉调直。故回答时,至少要分成两部分来答题。

(1)根据《混凝土结构工程施工质量验收规范》GB50204~2002(2011年版)条文说明第5.2.1条规定,钢筋进场时,应检查产品合格证和出厂检验报告,并按相关标准的规定进行抽样检验。由于工程量、运输条件和各种钢筋的用量等的差异,很难对钢筋进场的批量大小作出统一规定。实际检查时,若有关标准中对进场检验作了具体规定,应遵照执行;若有关标准中只有对产品出厂检验的规定,则在进场检验时,批量应按下列情况确定:

①对同一厂家、同一牌号、同一规格的钢筋,当一次进场的数量大于该产品的出厂检验批量时,应划分为若干个出厂检验批量,按出厂检验的抽样方案执行。

②对同一厂家、同一牌号、同一规格的钢筋,当一次进场的数量小于或等于该产品的出厂检验批量时,应作为一个检验批量,然后按出厂检验的抽样方案执行。

③对不同时间进场的同批钢筋,当确有可靠依据时,可按一次进场的钢筋处理。

(2)根据《混凝土结构工程施工质量验收规范》GB50204~2002(2011年版)第5.3.3条规定,钢筋宜采用无延伸功能的机械设备进行调直,也可采用冷拉调直。当采用冷拉调直时,HPB300光圆钢筋的冷拉率不宜大于4%;HRB335、HRB400、HRB500、HRBF335、HRBF400、HRBFS00及RRB400带肋钢筋的冷拉率不宜大于1%。

由此可见,采用冷拉方法调直钢筋并没有错,不正确的地方是控制3%的冷拉率。对于Ⅱ级钢筋,冷拉率不应超过1%。

问答题

Power StruggleArnold Schwarzenegger has a mission: he wants to terminate global warming. In June, the California governor called for the state to cut down drastically its greenhouse-gas emissions to 80% of 1990 levels in the next 45 years. "The debate is over," he said in a forthright speech in San Francisco. "We know the science. We see the threat. And we know the time for action is now."This was fighting talk, but if any advanced economy can pull off such drastic cuts in emissions, this high-technology Pacific Rim state and its 36 million residents probably can. Schwarzenegger has help. He gets support from a team of state energy-conservation experts who have been in the business for years. And first among them is Arthur Rosenfeld. More than three decades ago, Rosenfeld helped to trigger the state’’s successful fight to cut energy consumption; today he is one of the five members of California’’s Energy Commission.Rosenfeld spent decades as a physics professor at the University of California, Berkeley. He now commutes weekly between his home overlooking San Francisco Bay and Sacramento, the capital, in an energy-saving car that the state provides. The Energy Commission’’s job isn’’t easy: to help the most populous US state figure out how it might cut greenhouse-gas emissions and make money doing it.Under controlIn his office, Rosenfeld pulls out a data plot of which he is particularly fond. It shows electricity consumption per capita from 1960 to 2002, with one line for California and one for the United States. In 1960, both lines sit at 4,000 kilowatt-hours per person. They rise at roughly the same pace to about 7,000 kilowatthours in the early 1970s. But at the point when the US energy crisis struck that decade, the lines diverge dramatically: California virtually flatlines its energy use per citizen — even though its economy was outpacing the rest of the nation. The state’’s electricity use per capita today is the lowest in the nation at 6,800 kilowatt-hours, compared with 12,800 kilowatthours for the country overall.The strategies that helped California achieve those conservation goals may now help it in its greenhouse-gas cuts. State energy experts, including Rosenfeld, don’’t foresee California adopting many radical new technologies to meet its ambitious goals. Rather, a steady application of proven technologies should do much of the job.California’’s $1.5-trillion gross annual product makes it the world’’s sixth largest economy, behind France and ahead of Italy. It is the planet’’s ninth-largest emitter of greenhouse gases. "California is not an insignificant actor, and we are seen as a world leader in protecting the environment," says Eileen Tutt, a senior officer at the California Environmental Protection Agency.Still, the governor’’s pledge, made on the United Nations World Environment Day, invited more support. Schwarzenegger is a tax-cutting Republican who is deeply suspicious of government regulation. Beset by budget fights and union opposition, he has dropped in popularity with the state’’s generally Democratic voters since his election two years ago. But his energy policies, building on those of a string of governors of both parties, get him reputation from longtime activists. "The governor is a real-life climate action hero today," Nancy Ryan, a senior economist with the group Environmental Defense, told reporters.Specifically, Schwarzenegger vowed that California will cut its greenhouse-gas emissions to below 2000 levels by 2010 and to less than the 1990 level of 373 million tonnes by 2020. But then the governor added the final, ambitious goal to cut emissions by a further 80% by 2050.Out on a limbHis policy stands in opposite contrast to that of the federal administration under President George W. Bush, who has refused to ratify the Kyoto Protocol to reduce greenhouse-gas emissions. The president has said that such action would squeeze the US economy too much. California officials say that they can do it while boosting the economy and creating jobs. The state’’s p environmental policies in the past, they point out, occurred while its economy thrived.Success will require the cooperation of several interlocking agencies. The Energy Commission plays a major role, as do the state’’s Environmental Protection Agency, Air Resources Board and Public Utilities Commission. Schwarzenegger’’s proclamation renewed their "absolute licence to go out and make California a model country for greenhouse policies", says Stephen Schneider, a physicist and climate-policy analyst at Stanford University.State officials have much at stake. California’’s climate could change utterly if a warmer world redirected storm paths. Rising temperatures could cause winter rain instead of snow in the Sierra Nevada mountains, triggering floods for which the state’’s aqueducts(沟渠) and dams are not prepared. Plus, its coast is vulnerable to a rise in sea level.Other states have also recognized their vulnerability to climate change, and have independently taken climate policy into their own hands. Local legislators, from mayors of cities to state governors, have begun their own versions of Kyoto-like regulations. In the northeast, nine states have agreed to limit carbon dioxide emissions from more than 600 power plants in the region. On the west coast, California has joined with Oregon and Washington in a governors’’ initiative to encourage energy efficiency and conservation.But of all the states, California’’s example has caused effect: in recent years many other states have adopted California’’s standards for car pollution rather than the more lax federal standards.And the state is now attracting international attention. In September, its Public Utilities Commission, Energy Commission and the Pacific Gas and Electric Company signed a pact (合同) with China’’s Jiangsu province to train officials and utility executives in energy-conservation tactics. Earlier this month, Schwarzenegger led a sales delegation to China to tout (吹捧) the state’’s energy-saving technologies, and another team from the state’’s Air Resources Board travelled to Belgium to brief European air-quality experts on energy policies.California’’s approach to energy conservation has helped it save money. The state sets electricity rates for private utilities, and sometimes provides subsidies to help power companies induce customers to cut their consumption. If they do, the state gives money back to the companies — through rate adjustments and other payments — that makes up for what the firms would have earned had they built additional power plants.The Energy Commission calculates that the total power bill for residents is about $16 billion lower each year than if the state had not launched its conservation campaign. Conservation has also managed to prevent some 18 million tonnes of carbon pollution being emitted from power plants — equivalent to taking 12 million cars off the roads. After allowing for the cost of measures such as changed building practices, appliances and subsidies, the net saving is about $12 billion.And deeper energy cuts should pay more, the commission says. The Air Resources Board estimates that planned reductions in greenhouse-gas emissions by 2020, from motor vehicles alone, could save Californians $256 million annually by 2010 (mostly from smaller fuel bills), and $4.8 billion annually by 2020.Cut and dried But will the state’’s longer-term emissions policy succeed Schneider is unsure how cost-effective the whole plan will be. Earlier stages may pay for themselves, he says, but the final leap to the 80% cut is unlikely to come without costs. "It would take a total modification of our fuel infrastructure(基础设施)," he notes.So far, even state planners aren’’t sure how they will meet the later goals. "We don’’t have the details, but we’’ll have a report to the governor’’s office in January," says Tutt.Some fresh ideas are already in the works. One notion, is to place 1 million solarpanel (太阳能) systems on rooftops by 2018. California gets about 11% of its electricity from geothermal, wind, biomass and solar units; for the United States overall, the number is around 2%. California aims to increase its share of renewable sources to 20% by 2010 and to 33% by 2020.Also helpful will be the vehicle clean-up legislation enacted just before Schwarzenegger’’s arrival. This requires car manufacturers, starting in 2009, to cut greenhouse-gas emissions from new cars and trucks by 22% by 2013 and 33% by 2017. But the law remains in dispute — perhaps predictably, car companies have sued. They argue that carbon dioxide is not a pollutant, and that regulating it at state level would pre-empt (先占) federal control over the fuel-efficiency standards in new cars. In the long run, the governor has chosen hydrogen-fuelled cars as his personal crusade.Wind power figures large in state plans. California pioneered wide-scale use of it and already has more than 14,000 wind turbines. In a good breeze their combined capacity is 2,100 megawatts — about the same as two nuclear power plants. State energy officials estimate that wind alone, in principle, can generate an additional 30,000 megawatts.

California obtains about 11% of its electricity from________,________, ________and________.

单项选择题