Question

中文翻译

Concrete is strong in compression, but weak in tensions: its tensile strength varies from 8 to 14 percent of its compressive strength. Due to such a low tensile capacity, flexural cracks develop at early stages of loading. In order to reduce or prevent such cracks from developing, a concentric or eccentric force is imposed in the longitudinal direction of the structural element. This force prevents the cracks from developing by eliminating or considerably reducing the tensile stress at the critical midspan and support sections at service load, thereby raising the bending, shear, and torsional capacities of the sections. The sections are then able to behave elastically, and almost the full capacity of the concrete in compression can be efficiently utilized across the entire depth of the concrete sections when all loads act on the structure.
Such an imposed longitudinal force is called a prestressed force, i.e., a compressive force that prestresses the sections along the span of the structural element prior to the application of the transverse gravity dead and live loads or transient horizontal live loads. The types of prestressing force involved, together with its magnitude, are determined mainly on the basis of the type of system to be constructed and the span length and slenderness desired. Since the prestressing force is applied longitudinally along or parallel to axis of the member, the prestressing principle involved is commonly known as linear prestressing.
Circular prestressing, used in liquid containment tanks, pipes, and pressure reactor vessels, essentially follows the same basic principles, as does linear prestressing. The circumferential hoop, or “hugging” stress on the cylindrical or spherical structure, neutralizes the tensile stresses at the outer fibers of the curvilinear surface caused by the internal contained pressure.
From the preceding discussion, it is plain that permanent stresses in the prestressed structural member are created before the full dead and live loads are applied in order to eliminate or considerably reduce the net tensile stresses caused by these loads. With reinforced concrete, it is assumed that the tensile strength of the concrete is negligible and disregarded. This is because the tensile forces resulting from the bending moments are resisted by the bond created in the reinforcement process. Cracking and deflection are therefore essentially irrecoverable in reinforced concrete once the member has reached its limit state at service load.
The reinforcement in the reinforced concrete member does not exert any force of its own on the member, contrary to the action of prestressing steel. The steel required to produce the prestressing force in the prestressed member actively preloads the member, permitting a relatively high controlled recovery of cracking and deflection. Once the flexural tensile strength of the concrete is exceeded, the prestressed member starts to act like a reinforced concrete element.

Answer 1

混凝土是在压缩强劲，但紧张弱，其拉伸强度变化从8至14％，其抗压强度。由于这种低抗拉能力，在装货的早期阶段弯曲裂缝的发展。为了减少或防止来自发展中国家如裂缝，同心或偏心的力量施加在纵向方向的结构元素。这股力量阻止来自发展中国家的裂缝，以消除或大大减少，在关键的跨设备和支持服务负载部分的拉应力，从而提高了部分弯曲，剪切，扭转能力。的部分，然后能够表现弹性，几乎满负荷生产的混凝土在压缩，可以有效地利用各地的具体章节的整个深度时，所有负载结构的行动。
这种强加的纵向力，被称为预应力力量，即，压缩力，部分预应力沿跨度结构元素之前死和活荷载或暂态水平活荷载横向重力的应用。涉及预应力类型的，其规模，主要是对系统建设跨度和所需的细长型的基础上确定。由于纵向预应力施加沿着或平行于轴的成员，预应力原则通常被称为线性预应力。
预应力圆形，遏制液体储罐，管道，压力反应容器中使用，基本上遵循相同的基本原则，如线性预应力。环箍，或“拥抱”的圆柱形或球形结构上的压力，中所载的内部压力所造成的曲线表面的外层纤维的拉伸应力。
从前面的讨论，这是平原之前创建完整的死和活荷载适用于以消除或大大减少这些负载造成的净拉伸应力，预应力结构构件的永久应力。钢筋混凝土，混凝土的抗拉强度是微不足道的，无视。这是因为从弯矩产生的拉力是在加固过程中创建的债券抵制。开裂和挠度，因此在钢筋混凝土的成员基本上是无法挽回的，一旦在业务负荷已达到其极限状态。
在钢筋混凝土构件的加固，不施加任何成员自身的力量，相反的行动预应力钢。所需的生产预应力成员的预应力钢积极预装的成员，允许一个相对高的开裂和挠度的控制复苏。一旦超过混凝土的弯曲拉伸强度，预应力成员开始像钢筋混凝土元素。

追问

大部分都不对啊翻译的，能专业点吗，百度翻译的很不专业