本章主要介绍桥梁动力特性、作用于桥梁上的风 荷载的计算及桥梁动力失稳判断等内容。此处的桥 梁动力特性主要涉及桥梁的自振周期及频率,本章 介绍了如何用结构动力学方法和一些经验公式进行 计算。风荷载计算在基准风压基础上考虑了重现期 结构体型、地形、地理条件等因素的影响。桥梁动 力失稳包括颤振失稳和驰振失稳,本章介绍失稳机 理及如何用运动方程和经验公式来判断桥梁是否可 能发生动力失稳

Determination of the relative movement of the two walls from the tension joints

TERMINOLOGY FOR DISPLACEMENT a is the rake angle

Main Bedding Types Bedding Shape level bedding ripple bedding Main Types of plate laminae

CONSTRUCTION OF VERTICAL SECTION 1 Select the location of the section and draw a section line (usually perpendicular to the strike of the main structures), right-hand end is its more easterly end 2 Draw a topographic profile along the line of section. Determine the base line on the squared

Review Show the homework and note book on your desk Practise measurement of attitude of planes and lines in the models

Determination of the top sur faces of the beds from the scour surfaces

Chapter 2 Primary Sedimentary Structures Main types of bedding Determination of younger direction of beds from primary structures Types of stratigraphic break Angular unconformity Soft sedimentary structures

Chapter One Introduction Goals Outline Two supports Types of structures QA uantitative techniques pplication Suggestion

前面介绍了曾占主流地位的古典与新古典贸易理论。本章介绍解释当代国际贸易理 论。由于这些理论改变了传统贸易理论假设条件,分析框架也不同,称为“现代国际贸易 理论”。 20世纪70年代末是贸易理论发展的分水岭此前,几乎所有研究都以完全竞争为假 设,它们成功地解释了产业间贸易、国际资本流动、技术优势决定分工与贸易格局的问 题,并且支持自由贸易或不干预政策