钢筋混凝土框架结构设计应从概念设计上着手注意几个问题发布时间：2015-9-21 9:47:22 浏览次数:594
1. Pay attention to the seismic design.
(1) the structure of the basis of seismic design. Seismic design is the basis of strength and ductility. People have now realized that can take advantage of the yield of inelastic deformation of reinforced concrete structures to resist earthquake, which is combining both the strength and ductility to resist earthquake. In order to ensure the seismic capacity of the structure, the structure design, if we give structure to set the bearing capacity of the lower level, accordingly requires structure has high ductility level; If we are to set higher bearing capacity level structure, the structure need to ductility level can be low. On the problem of the specific processing, there was some difference of the concept of all countries.
(2) the capacity design method. Capacity design method, the basic idea is: in order to make the aseismatic reinforcement concrete structure formed in the earthquake's pursuit of "beam hinge institutions" or "beam hinge institutions", unwanted plastic hinge you need to put plastic hinge or don't want to come first (that is, don't want too much plastic rotation) of the bending capacity of the relative increase; In order to not be before the ductility of the structure show the required in any part of the structure appear almost no ductile shear failure, also need to enhance the relevant parts of the relative shear capacity; Also need to take the necessary measures to make the parts of plastic hinge can be formed with sufficient capacity and ductility of the necessary energy dissipation.
2. About the strong column weak beam node. In order to realize this is under severe earthquake, let the beam end plastic hinge formation, inelastic performance of column end, and not to yield, but the node is still in the elastic work stage. The strength of the strong column weak beam measures, that is, relative to end section of the actual beam bending capacity of flexural capacity increases in the cross section at the end of the size, is decided after cross section at the end of the yield caused by earthquake plastic rotation can be no more than the plastic rotation capacity, and does not form "layer of lateral institutions", so that the column is not the key of the crushing of control measures. The size of column strong beam size depends on the structure of the beam end longitudinal reinforcement is inevitable with any degree of size, and structure in the beam, the plastic hinge at the end of the plastic internal force redistribution in the process of gradually formed and the dynamic characteristics of the corresponding change. When building permits, therefore, as far as possible to do the column section size bigger, make line stiffness of column and beam line stiffness ratio greater than 1 as far as possible, and control of axial compression ratio meet the specification requirements, to increase the ductility. When calculating the ultimate capacity, according to column design of curved distance will artificially strong column weak beam principle adjust amplification, strengthen column reinforcement structure. Beam end longitudinal reinforcement steel shall not be too high, to avoid entered the stage of yield in severe earthquake could not form plastic hinge or the plastic hinge is transferred to post. Pay attention to the node structure, let to the beam plastic hinge moved in across.
3. Pay attention to the construction measures.
(1) for the frame structure of the large span column grid, in the framework of stair place column due to the landing beam and is linked together, make the stairs q may be short column, the column length column stirrup encryption. This, easy to be ignored in the design, should be taken into consideration seriously.
(2) the window frame structure facade for the band, because of setting continuous window lintel, make the outer frame column may be short column, should be paid attention to strengthen the construction measures.
(3) the length is slightly more than the standard limit for frame structure, building function need not allowed, the seam is to reduce the harmful cracks in the rules and regulations of (crack width is less than 0.3 mm), recommended compensation concrete pouring. With fine and dense two-way reinforcement, construct the spacing should be less than 150 mm, the post-cast strip on the roof should be set up, after pouring belt according to the structural measures should be appropriate to strengthen.
(4) other structural measures shall be limited to, go here, please see the new specification.
4. About "strong shear weak bending" measures: strong shear weak bending ductility is to ensure that components, to prevent the brittle failure of the important principles, it requires artificially increase the bearing component relative to the shear capacity of the flexural capacity, make these parts in the structure of the experience of the rarely met earthquake with enough assurance does not appear in the process of brittle shear failure. Should be paid attention to for the frame structure of the frame beam shear calculation and structure, make it meet the requirements of the relevant specification.