【正文】 walls in two perpendicular directions can be at least in sufficient orientation so that lateral force in any direction can be resisted . In addition , that wall layout should reflect consideration of any torsional effect . In design progress , two or more shear walls can be connected to from Lshaped or channelshaped subsystems . Indeed , internal shear walls can be connected to from a rectangular shaft that will resist lateral forces very efficiently . If all external shear walls are continuously connected , then the whole buildings acts as tube , and connected , then the whole buildings acts as a tube , and is excellent ShearWall Seystems resisting lateral loads and torsion . Whereas concrete shear walls are generally of solid type with openings when necessary , steel shear walls are usually made of trusses . These trusses can have single diagonals , “X”diagonals , or“K”arrangements . A trussed wall will have its members act essentially in direct tension or pression under the action of view , and they offer some opportunity and deflectionlimitation point of view , and they offer some opportunity for peration between members . Of course , the inclined members of trusses must be suitable placed so as not to interfere with requirements for wiondows and for circulation service peratio ns though these walls . In many highrise buildings , a bination of walls and shafts can offer excellent resistance to lateral forces when they are suitably located ant connected to one another . It is also desirable that the stiffness offered these subsystems be moreorless symmertrical in all directions . RigidFrame Systems In the design of architectural buildings , rigidframe systems for resisting vertical and lateral loads have long been accepted as an important and standard means for designing building . They are employed for lowand medium means for designing buildings . They are employed for low and medium up to highrise building perhaps 70 or 100 stories high . When pared to shearwall systems , these rigid frames both within and at the outside of a buildings . They also make use of the stiffness in beams and columns that are required for the buildings in any case , but the columns are made stronger when rigidly connected to resist the lateral as well as vertical forces though frame bending . Frequently , rigid frames will not be as stiff as shearwall construction , and therefore may produce excessive deflections for the more slender highrise buildings designs . But because of this flexibility , they are often considered as being more ductile and thus less susceptible to catastrophic earthquake failure when pared with ( some ) shearwall designs . For example , if over stressing occurs at certain portions of a steel rigid frame ( .,near the joint ) , ductility will allow the structure as a whole to deflect a little more , but it will by no means collapse even under a much larger force than expected on the structure . For this reason , rigidframe construction is considered by some to be a “best”seismicresisting type for highrise steel buildings . On the other hand ,it is also unlikely that a welldesigned sharewall system would collapse. In the case of concrete rigid frames ,there is a divergence of opinion . It true that if a concrete rigid frame is designed in the conventional manner , without special care to produce higher ductility , it will not be able to withstand a catastrophic earthquake that can produce forces several times lerger than the code design earthquake forces . therefore , some believe that it may not have additional capacity possessed by steel rigid frames . But modern research and experience has indicated that concrete frames can be designed to be ductile , when sufficient stirrups and joinery reinforcement are designed in to the frame . Modern buildings codes have specifications for the socalled ductile concrete frames . However , at present , these codes often require excessive reinforcement at certain points in the frame so as to cause congestion and result in construction difficulties 。 the trusses are placed often at mechanical floors, mush to the disapproval of the designers of the mechanical systems. Nevertheless, as a costeffective structural system, the belt truss works well and will likely find continued approval from designers. Numerous studies have sought to optimize the location of these trusses, with the optimum location very dependent on the number of trusses provided. Experience would indicate, however, that the location of these trusses is provided by the optimization of mechanical systems and by aesthetic considerations, as the economics of the structural system is not highly sensitive to belt truss location. The tubular framing system mobilizes every column in the exterior wall in resisting overturning and shearing forces. The term?tubeintube?is largely selfexplanatory in that a second ring of columns, the ring surrounding the central service core of the building, is used as an inner framed or braced tube. The purpose of the second tube is to increase resistance to over turning and to increase lateral stiffness. The tubes need not be of the same character。 高層建筑的豎向構(gòu)件從上到下逐層對(duì)累積的重力和荷載進(jìn)行傳遞，這就要有較大尺寸的墻體或者柱體來進(jìn)行承載。地震荷載的效應(yīng)更為明顯。 不幸的是，對(duì)于高層建筑首先要解決的不僅僅是抗剪問題，還有抵抗力矩和抵抗變形問題。用于抵抗側(cè)向荷載的材料要求更多。在地震荷載作 用下，頂部質(zhì)量的增加將會(huì)使側(cè)向荷載劇增。但是必須保證加寬后的豎向承重構(gòu)件非常有效地連接。例如，增加較低層柱以及連接大梁的翼緣截面，將可直接減少側(cè)向位移和增加抗彎能力，而不會(huì)加大上層樓面的質(zhì)量，否則，地震問題將更加嚴(yán)重。但僅僅通過豎向構(gòu)件進(jìn)行抗剪是不經(jīng)濟(jì)的，因?yàn)槭怪傲河凶銐虻目箯澞芰?，比用墻或斜撐需要更多材料和施工工作量? 應(yīng)當(dāng)注意的是，所有高層建筑的本質(zhì)都是地面支撐的懸臂結(jié)構(gòu)。同時(shí)，這些構(gòu)件還要將風(fēng)荷載及地震荷載等側(cè)向荷載傳給基礎(chǔ)。 對(duì)于低層和多層建筑物設(shè)計(jì)只需考慮恒荷載和部分動(dòng)荷載時(shí)，建筑物的柱、墻、樓梯或電梯等就自然能承受大部分水平力。應(yīng)當(dāng)注意的是，因混凝土材料的質(zhì)量增加而帶來的建筑物自重增加，要比鋼結(jié)構(gòu)增加得多，而為抵抗風(fēng)荷載的能力而增加的材料用量卻不是呢么多，因?yàn)榛炷磷陨淼闹亓靠梢缘挚箖A覆力矩。增加抗彎構(gòu)件的有效寬度。 應(yīng)當(dāng)注意的是，所有高層建筑的本質(zhì)都是地面支撐的懸臂結(jié)構(gòu)。例如，住宅樓需要很多隔