题目

英语翻译
Concrete is characterized by strong compressive strength,but is relatively weak in tension and shear.It can support large axial loads,and is used extensively in the foundations of large structures such as bridges and tall buildings.but it breaks easily under bending without reinforcing steel.Concrete with compressive strength of 3,000 6,000 pounds per square inch (psi) is common.
The American Concrete Institute defines any concrete over 6,000 psi as high-strength concrete.
For structures that require flexural strength for resistance to bending moments,reinforcing steel--rebar--is embedded in the concrete.In some cases,tensioned cables are placed in the concrete to make prestressed or post-tensioned concrete.The tension to resist the bending moment comes from the reinforcing steel or the stressed cables.
For a concrete mix to reach its ultimate strength,a long period of time is needed.The ultimate strength of concrete and its 28-day strength are not the same.For des

提问时间：2020-11-22

答案

很简单的一段翻译,太懒了:( 感觉我.
keli1987好像不是土木工程专业的吧
Concrete is characterized by strong compressive strength,but is relatively weak in tension and shear.It can support large axial loads,and is used extensively in the foundations of large structures such as bridges and tall buildings.but it breaks easily under bending without reinforcing steel.Concrete with compressive strength of 3,000 6,000 pounds per square inch (psi) is common.
混凝土材料特点是抗压能力强,抗拉和抗剪切能力差.能够承受很大的轴向压力,能够广泛的应用与桥梁和高层建筑的基础.但是如果不加钢筋,其很容易破坏.混凝土一般具有3,000 6,000psi抗压强度.（1psi=0.069公斤=6900Pa）
The American Concrete Institute defines any concrete over 6,000 psi as high-strength concrete.
For structures that require flexural strength for resistance to bending moments,reinforcing steel--rebar--is embedded in the concrete.In some cases,tensioned cables are placed in the concrete to make prestressed or post-tensioned concrete.The tension to resist the bending moment comes from the reinforcing steel or the stressed cables.
美国混凝土协会定义超过6,000 psi抗压强度的混凝土为高强混凝土.
对于结构来说,需要弯曲应力去抵抗弯矩,因此钢筋被嵌入到混凝土材料中.有些情况,拉索（预应力筋）埋入混凝土构成预应力混凝土,可以采用先张法或者后张法.钢筋或者预应力索的拉力用于抵抗弯矩.
For a concrete mix to reach its ultimate strength,a long period of time is needed.The ultimate strength of concrete and its 28-day strength are not the same.For design purposes,engineers use the 28-day strength,and the concrete should be subjected to only minimum loads until the 28 days have passed.That rule is very rigidly enforced in heavy construction.It is not at all uncommon for work in residential and medium-rise commercial building construction to be processed on a 3-day floor cycle.Place concrete one day,form and shore the next floor over the next two days,this puts minimum load on the new slab,and then place concrete on the third day.This placement increases the load on the previously placed floor,but the load is carried primarily by the shoring,which passes continually down for several floors,thereby shifting the load to concrete that has had time to reach its ultimate strength.
Note the shoring and reshoring in Fig.6.5 is in place to a depth of four floors below the slab that is currently being placed.
混凝土达到极限承载力龄期需要很长时间.极限承载力和28天强度还有点区别.对于设计,工程师通常使用28天强度,混凝土未达到28天强度前仅能承受很小的荷载.这个规定在特殊建筑中需要强制执行.不同于一般的住宅和多层商业建筑可以3天作一个楼层.浇注混凝土1天,接下来2天给下一层支模,给新浇注的楼板最小的荷载,然后第三天再浇混凝土.这种浇注方法给前一层浇注的楼层施加荷载,但是这部分荷载主要给支撑模板,模板能把这部分荷载分散到先前的若干层上,因此这部分荷载能够分散到以前达到极限强度的楼层上.注意,图6.5的板下面4层楼高的支架已替换.
（ultimate strength of concrete
The compressive strength of concrete continues to increase slowly for many months.The ultimate strength may be higher than the 28-day strength,which is used for design calculations.）
（混凝土极限强度：混凝土抗压强度灾数月内缓慢增加,混凝土极限强度可能高于28天强度,其用于设计计算）