Ⅰ 混凝土受压区的应力图形用等效矩形应力图形代替的原则是什么
原则是:等效后受压区合力大小相等、合力作用点位置不变。
Ⅱ 铸造FCMB32是什么材质
FCMB32是日本标准的黑心可锻铸铁,对照我国牌号为:KTH330-08
如下图:
Ⅲ FcMB 是什么材料
Licensed in 1982, FCMB was the first bank to be established in Nigeria without government or foreign support. The bank enjoyed unparalleled success as a merchant bank and was one of the top two merchant banks in Nigeria up till its conversion to universal banking in 2001. One of its earliest landmark achievements was the completion of the first public loan syndication for the then National Fertilizer Company of Nigeria (NAFCON) in 1986, the largest at the time.
In 2000, the bank changed its name to First City Monument Bank in anticipation of an expansion of its services to universal banking. After 18 years of unbroken success as a merchant bank, FCMB widened its doors to retail customers in January 2001 and adopted universal banking. In December 2004, FCMB PLC shares were listed on the Nigerian Stock Exchange (NSE) officially joining the elite group of publicly quoted companies in Nigeria. Between 2004 and 2005, the bank successfully raised additional capital in excess of N20 billion through private and public offerings to exponentially grow its business and expand its physical and virtual presence.
FCMB has constantly been recognized as one of the most professionally managed and resilient financial services groups in the country. The bank is also known for a culture that has matured into a heritage of excellence. It has proced no less than 18 chief or deputy chief executives of leading banks in Nigeria, a testament of its entrepreneurial culture and rich heritage.
As a bank and through its subsidiary FCMB Capital Markets Limited, FCMB is widely recognized as Nigeria's most consistent and enring investment banking outfit. Its consistent service to leading corporate and public institutions over the last three decades shows a dedication to investment banking and solutions oriented banking.
The corporate finance and issuing house arm of the group has built unparalleled success. The group, which metamorphosed into FCMB Capital Markets has gained a strong position in public and private placements of debt and equity, mergers & acquisitions and structured finance by virtue of its experience in capital raising and financial advisory deals in the last two decades.
FCMB Capital Markets has remained the pre-eminent investment banking firm in Nigeria with a proven history of serving the financial needs of government, institutional, corporate and private clients.
The bank is the brainchild of Otunba Michael Olasubomi Balogun who had the belief, nurtured in the 1970’s and actualized in 1982, that a young Nigerian could have the capacity to build and manage a world class financial institution. It is a testament to his belief, determination and management that more than two decades later, what started as a vision, has matured into a broad based institution, retaining its traditions while reinventing itself to meet the ever present challenges and opportunities as an African player in a global economy.
[edit] Recognition and awards
Over the years, we have received several awards for outstanding financial performance, superior management and dedication to excellence. Some of these awards include:
* The prestigious Thisday Award for the "Stock Offer of The Year" in 2005, an acknowledgment of the success of our capital raising activities in a highly competitive period in the instry.
* In 2000 and 2001, FCMB Capital Markets won the Reuters/SBA Research Mergers & Acquisition Award as the leader in Mergers & Acquisition in Nigeria.
* Between 1993 and 1998, won the coveted trophy for the most consistent issuing house in Nigeria.
* An impressive A+/A1 rating from Global Credit Ratings, Africa's premier rating agency.
参考资料
http://en.wikipedia.org/wiki/FCMB
wikipedia
Ⅳ fcmb270是什么材质
CNS2936 FCMB270 FCMB31锻铸铁
Ⅳ FcMB 是什么材料
FcMB 是用的黑芯可锻铸铁材料。
可锻铸铁,由一定化学成分的铁液浇注成白口坯件,再经退火而成的铸铁,有较高的强度、塑性和冲击韧度,可以部分代替碳钢。可锻铸铁白口铸铁通过石墨化退火处理得到的一种高强韧铸铁。有较高的强度、塑性和冲击韧度,可以部分代替碳钢。它与灰口铸铁相比,可锻铸铁有较好的强度和塑性,特别是低温冲击性能较好,耐磨性和减振性优于普通碳素钢。这种铸铁因具有-定的塑性和韧性,所以俗称玛钢、马铁,又叫展性铸铁或韧性铸铁。黑心可锻铸铁用于冲击或震动和扭转载荷的零件,常用于制造汽车后桥、弹簧支架、低压阀门、管接头、工具扳手等。珠光体可锻铸铁常用来制造动力机械和农业机械的耐磨零件,国际上有用于制造汽车凸轮轴的例子。白心可锻铸铁由于可锻化退火时间长而较少应用(见铁素体可锻铸铁、珠光体可锻铸铁和白心可锻铸铁)。
Ⅵ SSB-D是什么材料
SSB(Single Side Band,是指单边带,使用电波波形的一半接收。比如用上边带(USB)或者下边带(LSB),剩下那一半波形因为形状是和那一半对称的,所以可以用接收机补全,上边带和下边带通信统称单边带。
在无线电通信中,单边带调制(SSB)或单边带抑制载波(SSB-SC),是一种可以更加有效的利用电能和带宽的调幅技术。调幅技术输出的调制信号带宽为源信号的两倍。单边带调制技术可以避免带宽翻倍,同时避免将能量浪费在载波上,不过因为设备变得复杂,成本也会增加。
单边带信号从本质上来说也是一种调幅信号,它出自于调幅又区别于调幅。调幅波是一个载波幅度跟随调制音频幅度变化而变化的调制方式。只有清楚的知道调幅波的频谱特征才能准确的掌握单边带。1KHz的调制信号对10MHz的载波信号进行调制,将得到一个调幅信号(AM)。对这个调幅信号进行分解将得到如下的频谱。频率低于载频的谱线为下边带(LSB),频率高于载频的谱线为上边带(USB)。但是,大多数的单边带电台都要发送语音信号,情况就要比上面的单频率调制的情况复杂些。单边带电台一般要传送300到3000赫兹的音频信号。
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链接: https://pan..com/s/13A3moLtpAFdjCwO3OWcEvg?pwd=fcmb
英俊不凡的民俊(宋一国 饰)是情场上的高手,性感的智媛(孙艺珍 饰)也相貌出众,能把异性深深吸引住。这两名恋爱高手被命运安排走到了一起。
Ⅷ 混凝土的应力分布与实际应力图形中应力分布的关系是什么
在建筑结构专业的《混凝土结构设计规范》GBJ10-89中(以下简称GBJ10-89),采用的是近似概率极限状态设计方法。以概率理论为基础,较完整的统计资料为依据,用结构可靠度来衡量结构的可靠性,按可靠度指标来确定荷载分项系数与材料分项系数,使设计出来的不同结构,只要重要性相同,结构的可靠度是相同的。
材料强度取值上的差别
2.1 混凝土的强度
混凝土立方体抗压强度是混凝土的基本强度指标,是用标准试块在标准养护条件下养护后用标准试验方法测得的强度指标。两规范中所采用的试块尺寸是不同的。GBJ10-89中采用150mm立方体试块,TJT023-85中用200mm的立方体试块。GBJ10-89中,根据测得的具有95%保证率的立方体抗压极限值来确定混凝土的强度等级,一共分为十级,即C10,C15,C20,C25,C30,C35,C40,C45,C50,C60.
TJT023-85中,根据测得到具有84.13%保证率的立方体抗压极限值来确定混凝土的强度等级,用混凝土标号表示,一共分为七级,即15号、20号、25号、30号、40号、50号、60号。由于所采用的试块尺寸不同,两规范中相同数值等级的混凝土强度值是不同的,GBJ10-89的值大。如C15混凝土与15号混凝土,尽管都表示强度等级为15Mpa的混凝土,但实际强度C15混凝土比15号混凝土大。混凝土强度取值不同,这一点在设计中是要注意的。
2.2 钢筋的强度
两规范中,钢筋的标准强度取值是一样的,都采用钢材的废品限制值作为取值依据。但钢筋的设计强度取值不一样,GBJ10-89中以标准强度值除以材料分项系数作为取值依据,而TJT023-85中设计强度取值与标准强度取值是一样的。这样,相同的钢筋等级,TJT023-85中钢筋的设计强度取值大。
3 荷载取值的差别
两规范中荷载分类与取值都有明确的规定,不容易混淆。在荷载效应组合中有一点差别,应注意。GBJ10-89中,荷载效应组合时,既有荷载分项系数,又有荷载组合系数,要区别开来。TJT023-85中只有荷载分项系数。
4 构件计算的差别
两规范中在构件计算上,尽管依据的原理、计算假定、计算模型基本一致,但计算公式、计算结果是有较大差别的。构件计算是关系到设计结果的最重要的一环,值得重视。限于篇幅,只以正截面受弯和斜截面受剪强度计算为例看计算上的差别。
4.1 正截面受弯强度计算
两规范在计算假定上就有差别。混凝土极限压应变取值,TJT023-85中为εu=0.003?GBJ10-89中εu=0.0033.在等效矩形应力图形中,TJT023-85取γσ=Ra?βx=0.9x.GBJ10-89中取γσ=1.1fc?βx=0.8x.由于εu取值不同,两规范中混凝土界限受压区高度有些差别。从混凝土极限压应变、等效矩形应力图形的差别上可以看出,两规范中安全储备是不同的。TJT023-85的安全储备大。
下面用算例来说明这一问题。
有矩形截面梁,截面尺寸为250mm×500mm?20号混凝土,Ⅱ级钢筋。计算截面处计算弯矩为Mj=15KN.m?试进行配筋计算。
4.1.1先按TJT023-85计算。
已知20号混凝土抗压强度设计值Ra=11Mpa?II级钢筋抗拉强度设计值Rg=340Mpa?混凝土相对界限受压区高度ξjg=0.55,材料安全系数γc=γs=1.25.
(1)求混凝土受压区高度x
先假定钢筋按一排布置,钢筋重心到混凝土受拉边缘的距离a=40mm,则有效高度h0=(500-40)mm=460mm由
得
解得X=133mm<ξjgh0=0.55×460=253mm.
(2)求所需钢筋数量Ag,由RgAg=Ra·bx,得
Ag= = =1076mm2
(3)验算最小配筋率μ= = =1%>μmin=
0.1%,满足规范要求。
4.1.2按GBJ10-89计算
C20混凝土,弯曲抗压强度设计值fcm=11Mpa,钢筋抗拉强度设计值fy=310Mpa?混凝土相对界限受压区高度ξb=0.544
(1)求X 有Mj=fcmb×(h0-)得115×106=11×250×(460- ),解得x=(1-1- )h0 =102.3mm<ξbh0=0.544×460=250.2mm满足要求
(2)求As由Asfy=fcmbx得As=fcmbx / fy=(11x250×102.3)/ 310=907.5mm2>μminbh0=0.15%×250×460=172.5mm2
如果扣除由于20号混凝土与C20混凝土之间强度取值的差别,20号混凝土按GBJ10-89,fcm=11×0.95=10.45MPa?则x=(1-1- )×460=108.5mm, As=(10.45x250x108.5)/310=914.4mm2
从上述计算中看出,按TJT023-85比按GBJ10-89钢筋用量多17.7%。
4.1.3 受弯构件斜截面强度计算
在斜截面强度计算中,两规范都是根据斜截面发生剪压破坏时的受力特征和试验资料所制定的。但两规范在计算公式表述上及计算结果上都有较大的差别。
TJT023-85中,斜截面强度计算公式为:Qj≤Qu=Qhk+QW,其中Qhk=0.0349bh0(2+p) R μkRgk,Qw=0.06Rgw∑Awsinα,式中Qj:根据荷载组合得出的通过斜截面顶端正截面内的最大剪力,即计算剪力,单位为KN;Qhk:混凝土和箍筋的综合抗剪承载力(KN);Qw:弯起钢筋承受的剪力(KN);b:通过斜截面受压区顶端截面上的腹板厚度(cm);h0:通过斜截面受压区顶端截面上的有效高度,自纵向受拉钢筋合力点至受压边缘的距离(cm);μk:箍筋配筋率?μk=nk·ak/(b·s);Rgk:箍筋的抗拉设计强度(Mpa),设计时不得采用大于340Mpa:R:混凝土标号(Mpa);p斜截面内纵向受拉主筋的配筋率,p=100μ,μ=Ag/bh0?当p>3.5时,取p=3.5;Rgw:弯起钢筋的抗拉设计强度(Mpa);Aw在一个弯起钢筋平面内的弯起钢筋纵截面面积(cm2);α:弯起钢筋与构件纵向轴线的夹角。
上式中工作条件系数、安全系数均已记入。公式的适用条件采用上限值和下限值来保证。上限值要求截面最小尺寸满足Qj≤0.051Rh0(KN)。满足下限值,Qj≤0.038R1bh0(KN)?可按构造要求配置箍筋,式中?R1:混凝土抗拉设计强度(Mpa)。GBJ10-89中,斜截面承载力的计算公式为V≤Vu=Vcs+Vsb?其中Vcs=0.07fcbh0+1.5fyv(Asv/ S)h0 ? Vsb=0.8fyAsbsinαs ?当为承受集中荷载的矩形独立梁,Vcs=0.2/(λ+1.5)fcbh0+1.25fyvh0,式中V:构件截面上的最大剪力设计值(N);Vcs:混凝土与箍筋的综合抗剪承载力(N);Vsb:弯起钢筋所承受的剪力(N);b:矩形截面的宽度,T形截面或I形截面的腹板宽度(mm);h0:通过斜截面受压区顶端截面上的有效高度,自纵向受拉钢筋合力点至受压边缘的距离(mm);fc:混凝土的抗压强度设计值(Mpa);fyv:箍筋的抗拉强度设计值(Mpa);S:沿构件长度箍筋间距(mm);fy:弯起钢筋的抗拉强度设计值(Mpa);Asb:在一个弯起钢筋平面内的弯起钢筋纵截面面积(mm2);αs:弯起钢筋与构件纵向轴线的夹角。
公式的适用条件也是采用上限值和下限值来保证。上限值要求截面最小尺寸满足V≤0.25fcbh0 当为薄腹梁,V≤0.2fcbh0 .满足下限值V=0.07 fbh0,可按构造要求配置箍筋。从上述公式中,可以看出,公式的表达形式不同,各物理量的单位也不同。