朝歌电视剧
外文翻译
结构设计
结构设计
Augustine J.Fredrich
摘要：结构设计是选择材料和构件类型，大小和形状以安全有用的样式承担荷载。一般说来，结构设计暗指结构物如建筑物和桥或是可移动但有刚性外壳如船体和飞机框架的工厂稳定性。设计的移动时彼此相连的设备（连接件），一般被安排在机械设计领域。
关键词：结构设计 ； 结构分析 ； 结构方案 ； 工程要求
Abstract: Structure design is the lection of materials and member type ,size, and configuration to carry loads in a safe and rviceable fashion .In general ,structural design i
mplies the engineering of stationary objects such as buildings and bridges ,or objects that maybe mobile but have a rigid shape such as ship hulls and aircraft frames. Devices相信我可以 with parts planned to move with relation to each other(linkages) are generally assigned to the area of mechanical .
Key words: Structure Design ； Structural analysis ；structural scheme ； Project requirements
Structure Design
Structural design involved at least five distinct phas of work: project 含鸟的诗句requirements, materials, structural甜甜的恋爱故事 scheme, analysis, and design. For unusual structures or materials a six pha, testing, should be included. The phas do not proceed in a rigid progression , since different materials can be most effective in different schemes , testing
can result in change to a design , and a final design is often reached by starting with a rough estimated design , then looping through veral cycles of analysis and redesign . Often, veral alternative designs will prove quite clo in cost, strength, and rviceability. The structural engineer, owner, or end ur would then make a lection bad on other considerations.
Project requirements. Before starting design, the structural engineer must determine the criteria for acceptable performance. The loads or forces to be resisted must be provided. For specialized structures, this may be given directly, as when supporting a known piece of machinery, or a crane of known capacity. For conventional buildings, buildings codes adopted on a municipal, county , or , state level provide minimum design requirements for live loads (occupants and furnishings , snow on roofs , and so on ). The engineer will calculate dead loads (structural and known, permanent installations ) during the design process.
For the structural to be rviceable or uful , deflections must also be kept within limits ,
since it is possible for safe structural to be uncomfortable桔红色 “bounce” Very tight deflection limits are t on supports for machinery , since beam sag can cau drive shafts to bend , bearing to burn out , parts to misalign , and overhead cranes to stall . Limitations of sag less than span /1000 ( 1/1000 of the beam length ) are not uncommon . In conventional buildings, beams supporting ceilings often have sag limits of span /360 to avoid plaster cracking, or span /240 to avoid occupant concern (keep visual perception limited ). Beam stiffness also affects floor “bounciness,” which can be annoying if not controlled. In addition , lateral deflection , sway , or drift of tall buildings is often held within approximately height /500 (1/500 of the building height ) to minimize the likelihood of motion discomfort in occupants of upper floors on windy days .
Member size limitations often have a major effect on the structural design. For example, a certain type of bridge may be unacceptable becau of insufficient under clearance for river traffic, or excessive height endangering aircraft. In building design, ceiling heights and floor-to-floor heights affect the choice of floor framing. Wall thickness and column sizes and spacing may also affect the rviceability of various framing schemes.
Materials 担心英语lection. Technological advances have created many novel materials such as carbon fiber and boron fiber-reinforced composites, which have excellent strength, stiffness, and strength-to-weight properties. However, becau of the high cost and difficult or unusual fabrication techniques required , they are ud only in very limited and specialized applications . Glass-reinforced composites such as fiberglass are more common, but are limited to lightly loaded applications. The main materials ud in structural design are more prosaic and include 台式机清灰steel, aluminum, reinforced 山字旁的字有哪些concrete, wood , and masonry .
Structural schemes. In an actual structural, various forces are experienced by structural members , including tension , compression , flexure (bending ), shear ,and torsion (twist) . However, the structural scheme lected will influence which of the forces occurs most frequently, and this will influence the process of materials lection.
Tension is the most efficient way to resist applied loads ,since the entire member cross ction is acting to full capacity and bucking is not a concern . Any tension scheme must
also included anchorages for the tension members . In a suspension bridge , for example ,the anchorages are usually massive dead weights at the ends of the main cables . To avoid undesirable changes in geometry under moving or varying loads , tension schemes also generally require stiffening beams or truss.
