【正文】 : At Level I, the architect must first establish, in conceptual terms, the overall spaceform feasibility of basic schematic options. At this stage, collaboration with specialists can be helpful, but only if in the form of overall thinking. At Level II, the architect must be able to identify the major subsystem requirements implied by the scheme and substantial their interactive feasibility by approximating key ponent properties .That is, the properties of major subsystems need be worked out only in sufficient depth to very the inherent patibility of their basic formrelated and behavioral interaction . This will mean a somewhat more specific form of collaboration with specialists then that in level I .At level III ,the architect and the specific form of collaboration with specialists then that providing for all of the elemental design specifics required to produce biddable construction documents . Of course this success es from the development of the Structural Material. Concrete Plain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other admixtures. The plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf the cement/water mix, resulting in hardened concrete. The fi nished product has high pressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its pressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to pensate for the weak tension regions in the reinforced concrete element. It is this deviation in the position of a reinforces concrete section from the homogeneity of standard wood or steel sections that requires a modified approach to the basic principles of structural design. The two ponents of the heterogeneous reinforced concrete section are to be so arranged and proportioned that optimal use is made of the materials involved. This is possible because concrete can easily be given any desired shape by placing and pacting the wet mixture of the constituent ingredients are properly proportioned, the finished product bees strong, durable, and, in bination with the reinforcing bars, adaptable for use as main members of any structural system. The techniques necessary for placing concrete depend on the type of member to be cast: that is, whether it is a column, a bean, a wall, a slab, a foundation. a mass columns, or an extension of previously placed and hardened concrete. For beams, columns, and walls, the forms should be well oiled after cleaning them, and the reinforcement should be cleared of rust and other harmful materials. In foundations, the earth should be pacted and thoroughly moistened to about 6 in. in depth to avoid absorption of the moisture present in the wet concrete. Concrete should always be placed in horizontal layers which are pacted by means of high frequency powerdriven vibrators of either the immersion or external type, as the case requires, unless it is placed by pumping. It must be kept in mind, however, that over vibration can be harmful since it could cause segregation of the aggregate and bleeding of the concrete. Hydration of the cement takes place in the presence of moisture at temperatures above 50176。many makers build scrapers of 8 cubic meters struck capacity, which carry 10 m 179。 struck capacity ( 25 m 179。, and the largest standard types are of about m 179。 and the articulated type of about m 179。 failure of some sections and subsequent transformation of the structure into a mechanism。 elastic or plastic deformation or creep that cause a substantial change of the geometry of the structure。 early or excessive cracks。 and corrosion. Computational methods used to verify structures with respect to the different safety conditions can be separated into: (1)Deterministic methods, in which the main parameters are considered as nonrandom parameters. (2)Probabilistic methods, in which the main parameters are considered as random parameters. Alternatively, with respect to the different use of factors of safety, putational methods can be separated into: (1)Allowable stress method, in which the stresses puted under maximum loads are pared with the strength of the material reduced by given safety factors. (2)Limit states method, in which the structure may be proportioned on the basis of its maximum strength. This strength, as determined by rational analysis, shall not be less than that required to support a factored load equal to the sum of the factored live load and dead load ( ultimate state ). The stresses corresponding to working ( service ) conditions with unfactored live and dead loads are pared with prescribed values ( service limit state ) . Fro m the four possible binations of the first two and second two methods,