Lesson Plan

• Review

• New Words and Phrases

• Reading and Translating—Unit Nine

• Classroom Exercises

Review

Unit Nine Structural Analysis and Structural

Design

单 元 9结构分析与结构设计

Structural analysis is the process of determining the forces and deformations in structures due to specified loads so that the structure can be designed rationally, and so that the state of safety of existing structures can be checked.

Structural analysis is the process of determining the forces and deformations in structures due to specified loads so that the structure can be designed rationally, and so that the state of safety of existing structures can be checked.

结构分析是确定在给定荷载下结构中产生的力和变形，以便使结构设计得合理并能检查现有结构的安全状况。

In the design of structures, it is necessary to start with a concept leading to a configuration which can then be analyzed. This is done so members can be sized and the needed reinforcing determined, in order to ：

In the design of structures, it is necessary to start with a concept leading to a configuration which can then be analyzed. This is done so members can be sized and the needed reinforcing determined, in order to ：

在结构设计中，必须先从结构的概念开始拟定一种结构型式，然后再进行分析。这样做能确定构件的尺寸以及所需要的钢筋，以便：

a) Carry the design loads without distress or excessive deformations (serviceability or working condition);

b) To prevent collapse before a specified overload has been placed on the structure (safety or ultimate condition).

a) Carry the design loads without distress or excessive deformations (serviceability or working condition);

b) To prevent collapse before a specified overload has been placed on the structure (safety or ultimate condition).

a) 承受设计荷载而不出现损坏或过大变形（正常使用或工作状态）；

b) 防止在规定的超载施加到结构上以前倒塌（安全性或极限状况）。

Since normally elastic conditions will prevail under working loads, a structural theory based on the assumptions of elastic behavior is appropriate for determining serviceability conditions.

Since normally elastic conditions will prevail under working loads, a structural theory based on the assumptions of elastic behavior is appropriate for determining serviceability conditions.

由于在工作荷载作用下，结构通常处于弹性状态，因此以弹性状态假设为基础的结构理论就适用于正常使用状态。

Collapse of a structure will usually occur only long after the elastic range of the materials has been exceeded at critical points, so that an ultimate strength theory based on the inelastic behavior of the materials is necessary for a rational determination of the safety of a structure against collapse.

Collapse of a structure will usually occur only long after the elastic range of the materials has been exceeded at critical points, so that an ultimate strength theory based on the inelastic behavior of the materials is necessary for a rational determination of the safety of a structure against collapse.

结构的倒塌通常在远远超出材料弹性范围，超出临界点后才会发生， 因而，建立在材料非弹性状态基础上的极限强度理论，是合理确定结构安全性，防止倒塌所必需的。

Looked at critically, all structures are assemblies of three-dimensional elements, the exact analysis of which is a forbidding task even under ideal conditions and impossible to contemplate under conditions of professional practice.

Looked at critically, all structures are assemblies of three-dimensional elements, the exact analysis of which is a forbidding task even under ideal conditions and impossible to contemplate under conditions of professional practice.

仔细地观察所有结构都是三维构件的组合体，对其进行精确的分析，甚至在理想状态下，也是一个棘手的工作，即使专业方法也无法考虑清楚。

For this reason, an important part of the analyst's work is the simplification of the actual structure and loading conditions to a model which is susceptible to rational analysis.

For this reason, an important part of the analyst's work is the simplification of the actual structure and loading conditions to a model which is susceptible to rational analysis.

由于这种原因，分析人员工作的一个重要部分是，将实际结构和荷载状态简化成一个易于合理分析的模型。

Thus, a structural framing system is decomposed into a slab and floor beams which in turn frame into girders carried by columns which transmit the loads to the foundations. Since traditional structural analysis has been unable to cope with the action of the slab, this has often been idealized into a system of strips acting as beams.

Thus, a structural framing system is decomposed into a slab and floor beams which in turn frame into girders carried by columns which transmit the loads to the foundations. Since traditional structural analysis has been unable to cope with the action of the slab, this has often been idealized into a system of strips acting as beams.

这样，结构框架系统可分解成板和楼盖梁，进而框架中的梁系以立柱为支撑，立柱将荷载传递到基础上。因为传统的结构分析不能分析板的作用，所以经常理想化成类似于梁的条形系统（ T 形梁，考虑板的贡献）。

Also, ordinary methods have been unable to cope with three-dimensional framing systems, so that the entire structure has been modeled by a system of planar subassemblies, to be analyzed one at a time.

Also, ordinary methods have been unable to cope with three-dimensional framing systems, so that the entire structure has been modeled by a system of planar subassemblies, to be analyzed one at a time.

同样，普通的方法不能处理三维框架系统，因此，利用各榀平面框架组合，建立整个结构的模型，分别加以分析。

The modern matrix-computer methods have revolutionized structural analysis by making it possible to analyze entire systems, thus leading to more reliable predictions about the behavior of structures under loads.

The modern matrix-computer methods have revolutionized structural analysis by making it possible to analyze entire systems, thus leading to more reliable predictions about the behavior of structures under loads.

现代的矩阵－计算机法可以分析整个系统，从而革新了结构分析，这样可对荷载作用下结构的性能做出更可靠的预测。

Actual loading conditions are also both difficult to determine and to express, and must be simplified for purposes of analysis.

Actual loading conditions are also both difficult to determine and to express, and must be simplified for purposes of analysis.

实际荷载状态也是很难确定和表达的，为了进行分析，必须进行简化。

Thus, traffic loads on bridge structures, which are essentially both of dynamic and random nature, are usually idealized into statically moving standard trucks, or distributed loads, intended to simulate the most severe loading conditions occurring in practice.

Thus, traffic loads on bridge structures, which are essentially both of dynamic and random nature, are usually idealized into statically moving standard trucks, or distributed loads, intended to simulate the most severe loading conditions occurring in practice.

例如，桥梁结构上的交通荷载基本上是动力的和随机性的，通常理想化成静态行驶的标准卡车或分布荷载，以用来模拟实际产生的最危险的荷载状态。

Classroom Exercises An efficient analyst must thus be in command of

the rigorous methods of analysis, must be able to reduce these to shortcut methods by appropriate assumptions, and must be aware of available design and analysis aids, as well as simplifications permitted by applicable building codes. An up-to-date analyst must likewise be versed in the bases of matrix structural analysis and its use in digital computers as well as in the use of available analysis programs or software.