探析异形柱结构设计

摘要：本文详细阐述了异形柱框架的受力特点，对设计实际工程中异形柱结构的分析计算、构造措施等方面进行了探讨，并给出成功的工程设计实例。
Abstract: this paper expounds on the loading characteristics of special-shaped column frame, the design of special-shaped column structure in practical engineering analysis and calculation, construction measures and so on are discussed in this paper, and successful engineering design example is given.
　　关键词：异形柱；框架
Key words: special-shaped columns; The framework
　　
　　1　前言
1 introduction
　　
　　近年来，异形柱框架或异形柱框架一剪力墙结构作为一种全新的结构形式广泛用于小高层住宅建筑中，相对于传统的短肢剪力墙或框架结构，能更好的满足建筑需求且造价略有降低，因此具有更好的经济效益和社会效益。该结构形式一般指同层内异形柱数量超过柱总数量10％的框架或框架剪力墙结构，适用抗震设防烈度为6度或7度的地区。
In recent years, special-shaped column frame or special-shaped columns frame shear wall structure as a new kind of structure widely used in small high-rise residential buildings, compared with the traditional short limb shear wall and frame structure, can better meet the construction demand and cost is slightly reduced, therefore has better economic and social benefits. Within the structure generally refers to namely special-shaped column more than 10% of the total number or frame shear wall structure, the framework of applicable seismic fortification intensity is 6 or 7 degrees.
　　
　　2　受力特点
2 mechanical characteristics
　　
　　异形柱是指柱截面摈弃了惯用的矩形柱，而采用多个小墙肢的组合截面柱子，由剪力墙演变而来。柱肢截面中各肢高厚比不大于4，常用的有L形、T形和十形，亦有采用Z形。柱肢宽度一般使用与墙体相同的厚度，一般为200～250mm，不大于300mm。肢长较大，《规程》规定不小于500mm，一般为600～800。除此之外，不等肢异形柱肢高比一般不超过1.6，各肢截面厚度不能相差过大。
Special-shaped columns is refers to the column section away from the conventional rectangular column, and use multiple small wall limb combination section columns, the shear wall. Column leg section high thickness ratio is not greater than 4 in each limb, commonly used is l-shaped, t-shaped and ten shape, also have use Z. Column limb width generally use the same as the wall thickness, average for 200 ~ 250 mm, no greater than 300 mm. Limb length is larger, "rules" regulation is not less than 500 mm, generally is 600 ~ 600. Besides, ranging from limb special-shaped column limb ratio is generally not more than 1.6, the leg section thickness can not differ too much.
　　虽然异形柱由剪力墙演变而来，但由于柱截面本身的特殊性，异形柱结构的受力特点既不同于剪力墙结构，也与普通框架相差很大，具有自己的独特性，在荷载作用的结构反应更加复杂。国内外大量的试验资料和理论分析证明，异形柱的破坏形态有：弯曲破坏、小偏压破坏、剪压破坏等，影响破坏形态的因素主要有：荷载角、轴压比、剪跨比、配箍率等。
Although special-shaped columns composed of shear wall has evolved, but due to the particularity of the column section itself, the load-bearing characteristics of the special-shaped columns is different in shear wall structure, and general framework also vary widely, has its own uniqueness, the load of the structure response is much more complicated. At home and abroad a large number of experimental data and theoretical analysis prove that the damage form of special-shaped columns are: bending failure, small bias damage and shear damage, etc., are the major factors influence the failure pattern, loading Angle, axial compression ratio, shear span ratio, stirrup ratio and so on.
　　2．1整体计算分析
2.1 overall calculation and analysis
　　异形柱的存在和不同的布置对结构整个抗侧力刚度影响很大，总体来讲相对于同样布置的同截面矩形柱结构，异形柱结构的整体性要好，刚度略由增强；而单结构形式来讲，异形柱结构的刚度介于普通框架和框架剪力墙之间。文献[2]对8度区－6层住宅分别采用矩形柱和异形柱框架进行设计，然后分别采用SATWE和CRSC程序对比分析，结果表明在地震作用下异形柱结构的底部剪力要比矩形柱框架结构大16％～26％左右，各层柱的平均剪力和节点剪力也比矩形柱框架大很多。异形柱结构的受力特点介于普通框架柱和剪力墙之间，结构的抗震性能比较差，在内力分析计算时，既不能完全按普通框架柱，也不能完全照搬短肢剪力墙。
The existence of the special-shaped columns and different arrangement of great influence on the whole stiffness to resist lateral force structure, in general compared to the same arrangement with the cross section of the rectangular column structure, special-shaped column structure integrity is better, slightly by enhancing stiffness; And single structure, special-shaped column structure stiffness between ordinary frame and shear wall frame. Literature [2], respectively for 8 degrees area - 6 layer housing design and special-shaped column frame with rectangular column, and then respectively by using SATWE and CRSC program comparison and analysis, results show that the structure with special-shaped columns under seismic action at the bottom of the shear force is about 16% ~ 26% larger than the rectangular column frame structure, the average shear shear and node of each column is a lot larger than the rectangular column frame. Special-shaped column structure of mechanical characteristics between ordinary frame column and shear wall, the structure's seismic performance is poor, the internal force analysis and calculation, neither completely according to the common frame column, also can not completely copy the short limb shear wall.
　　根据规范要求，对于矩形柱结构，当无斜向抗侧力构件时，结构设计的地震作用方向一般取工程纵横轴方向，即0°和90°以此来求得地震作用下的结构内力，正截面承载力两个方向分别按单偏压计算配筋，其承载力基本上可以包络地震作用沿其他方向的情况。但对于异形柱，由于截面惯性矩沿不同方向差别很大，地震作用下柱受力的最不利方向不一定0°或90°，也就是说仅沿该两个方向计算的正截面配筋并不能完全包络地震作用沿其他方向时的情况，尤其在高烈度地区体现得更显著。对此，《规程》强制规定，7度及以上时地震作用尚应对与主轴成45°方向进行补充验算。
According to specification requirement, the rectangular column structure, when no oblique component to resist lateral force, structure design of the seismic action direction generally take engineering vertical and horizontal axis direction, namely 0 ° and 90 ° to obtain structural internal force under earthquake action, normal section bearing capacity of two directions respectively by single bias of reinforcement calculation, its bearing capacity can be basically envelope along other direction seismic action. But for special-shaped columns, as a result of section moment of inertia along different direction difference is very big, the earthquake under the action column stress does not necessarily the most unfavorable direction 0 ° or 90 °, that is to say, only along the direction of the two calculating the normal section of reinforced not completely enveloping along the other direction seismic action, especially in high intensity areas is more prominent. To this, "discipline" mandatory regulation, 7 degrees and above the seismic action is still coping with the spindle on supplement 45 ° direction.
　　考虑到受力后异形柱结构反应复杂，抗震性能不好，为符合“三水准两阶段”的抗震设计思路，地震作用计算后梁柱的内力调整都相对要求更严格些。对此，目前国内通用的结构设计软件PKPM并没有体现出来，虽然可以建立异形柱的模型，但尚未增加异形柱这种结构形式。其内部的内力调整和截面配筋计算仍然按照矩形柱或者短肢剪力墙的模式进行的，这难免会带来误差，有时可能相差甚远。天津大学开发的异形柱设计软件CRSC尚未普及。
Considering the complicated mechanical structure with special-shaped columns after response, seismic performance is not good, to meet the "three levels and two stage" seismic design train of thought, after the earthquake action calculation beam internal force adjustment are relative requirements more strict. To this, the current domestic general structure design software PKPM is not reflected, while it is possible to establish models of special-shaped columns, but not yet increase form the structure with special-shaped columns. Its internal internal force adjustment and calculation of steel is still in accordance with the rectangular column or short limb shear wall model, this will inevitably bring error, sometimes may be far. Special-shaped columns design software developed by tianjin university CRSC hasn't been widespread.
　　目前很多设计都是把异形柱作为短肢剪力墙，按短肢剪力墙结构利用PKPM等空间软件进行分析设计，误差大在所难免。相对精确的设计方法是：假设梁柱节点与普通框架梁柱节点相同，按等主轴刚度及等截面面积两个条件把异形柱截面转化成等效矩形柱截面，利用空间有限元分析程序进行内力分析，求出柱的内力重新按照有关异形柱截面的配筋计算公式进行截面配筋验算。但这种等效转化后的计算模型仍与实际结构有较大出入，由于异形柱肢长比较大，与梁相交时梁柱重叠部分较大，形成类似与壁式框架的梁柱刚域，梁的计算长度大大减小，实际结构的侧向刚度比计算模型大，导致地震力计算偏于不安全，文献[3]对柱内力在程序计算结果的基础上乘以约1.1的放大系数或者加大周期折减度以适当考虑其影响。但这也是权宜之计，且对于普通设计人员来讲过于费时费力，不利于提高效率。
At present a lot of design are the special-shaped column as a short limb shear wall, according to the space such as short limb shear wall structure by PKPM software carries on the analysis and design, error is inevitable. Relatively precise design method is: assume beam-column node is the same as the ordinary beam-column node, according to the spindle stiffness and the cross section area of the two conditions, such as special-shaped columns section is converted into equivalent rectangular column section, the use of space finite element analysis program for internal force analysis, the internal force of column again in accordance with the relevant calculation formula of special-shaped column section reinforcement section reinforcement calculation. But this kind of the calculation model of equivalent transformation after still have larger in and out, and the actual structure with special-shaped columns limb is larger, and larger beams intersect and overlap, form similar to Liang Zhugang domain wall frame, the calculation of beam length greatly decreases, and the actual structure of the calculation model for the lateral stiffness ratio is big, cause the earthquake force calculation be unsafe, the literature [3] on the internal forces of the column on the basis of calculation results are superior to about 1.1 degree of amplification coefficient or increasing cycle time reduction with due consideration of its impact. But this is temporary solution, and for ordinary designers are too time-consuming, not conducive to improve efficiency.
　　
　　2．2正截面受弯承载力和斜截面受剪承载力
2.2 flexural bearing capacity of normal section and inclined section shear bearing capacity
　　柱肢截面的差异，导致柱肢平面内外两个方向的截面特性相差较大，异形柱截面在轴压力及弯矩剪力共同作用下，正截面承载力的计算是一个十分复杂的问题，因为柱截面中和轴一般不与弯矩作用平面相垂直，也不与截面边缘平行，其位置随截面尺寸、混凝土强度、配筋率及荷载角等诸多因素的变化而变化。进而导致柱肢平面内外两个方向的惯性矩差异明显，进而侧向刚度相差较大，对不等肢的截面表现尤甚。因此普通柱正截面抗弯验算的计算公式并不适用于异形柱，《规程》将异形柱截面划分为有限个混凝土单元和钢筋单元，仍然采用平截面假定给出了双向偏压的正截面承载力验算公式。
Column leg section differences, cause inside and outside column limb planar section features large difference in two directions, special-shaped cross-section under axial stress and bending shear joint action, normal section bearing capacity calculation is a very complicated problem, because the column section neutral axis is generally not plane, vertical and bending moments is not with the cross section parallel to the edge, its position with the cross section size, concrete strength, reinforcement ratio and load Angle changes, and many other factors. Leading to column limb planar inside and outside two direction inertia difference is obvious, and the lateral stiffness is large, the range of limb section performance. So ordinary column calculation formula of normal section bending calculation does not apply to special-shaped columns, the regulation will be special-shaped column section is divided into a finite number of concrete and steel units, still with flat section assumption two-way bias of the normal section bearing capacity calculation formula is given.
　　由于多肢的存在，其截面的剪力中心往往在截面外，受力后主要依靠柱肢交点处的核心混凝土协调变形和传递内力，导致各柱肢内存在相当大的剪应力和翘曲应力，柱肢易首先出现裂缝，核心混凝土处于三向受剪状态，变形能力降低，脆性破坏特征明显。
As a result of the existence of multiple limbs, the cross section of shear center often outside the section, stress relies mainly on the column after limb intersection point of the core concrete coordination deformation and internal force, which caused a considerable in each column limb shear stress and warping stress of column limb first cracks easily, the core concrete in three-way shear condition, deformation is reduced, the characteristic of brittle failure is obvious.
　　异形柱的斜截面受剪承载力也随荷载作用方向而变化，但对同一方向的地震作用由于翼缘的有利作用，通常比等面积矩形柱高，文献[4]表明，T形截面柱的受剪承载力至少为同截面面积矩形柱的1.15倍，L形柱则基本相同。
Oblique section shear bearing capacity of special-shaped columns also varies with the loading direction, but in the same direction seismic action due to the effect of flange, are usually higher than such as area of rectangular column, literature [4] showed that the shear bearing capacity of t-shaped cross section column is to be at least 1.15 times with the cross section area of the rectangle column, l-shaped column is basically the same.
　　2．3节点强度
2.3 joint intensity
　　普通框架只要梁柱截面满足规范构造要求，节点核心区面积大，除二级或更高抗震等级的节点外，一般不需要特别进行节点抗剪验算。但异形柱框架的肢厚不大，节点核心区有效水平截面积小。另外，异形柱由于轴压比的要求，通常肢长较大，相对同截面面积的矩形柱来讲，刚度大，地震作用大，相应的节点剪力比相同布置下(柱面积相等)的矩形柱结构大很多。因此异形柱框架节点一般都需要验算节点抗剪强度。同时，异形柱肢厚度偏薄，节点斜压机制引起的核心区斜压力相对较大，钢筋握裹性能差，施工质量的可靠性也难以满足。
General framework as long as meet the requirements of normative structure of column section and beam section, the shear area is large, besides seismic grade node level 2 or higher, generally do not need special node shear and checking. But not thick limb of special-shaped column frame, the shear level effective cross-sectional area is small. In addition, special-shaped columns because of axial compression ratio requirements, limb length is larger, usually relatively with the cross section area of the rectangular column, stiffness big, seismic action, the corresponding node shear (column area equal) than under the same arrangement of rectangular column structure. Therefore typically require checking special-shaped columns frame node shear strength. Special-shaped columns limb thickness slants thin, at the same time, the node core oblique pressure caused by baroclinic mechanism is opposite bigger, grip performance is poor, the reliability of the construction quality is difficult to meet.
　　异形柱截面形式的不同，其节点受剪承载力也差别较大。十形截面柱的翼缘布置在节点截面中间受力最大的部位，翼缘的作用得以充分发挥，节点受剪承载力与同截面面积的矩形柱相差不大，T形截面次之，L形相差最大，受剪承载力下降最大。文献[5]研究表明：L形、T形、十形柱节点的受剪承载力比具有相同有效截面的矩形柱节点分别低33％、17.5％、8％左右，且用于矩形柱框架节点抗剪验算的公式已不适用于异形柱节点。在高烈度地区控制异形柱结构适用高度的参数已不单单是柱轴压比，而是节点区的强度。
Special-shaped columns section form different, the shear bearing capacity difference is bigger also. Ten shaped cross section column flange arrangement among the nodes section largest stress parts, to give full play to the role of the flange, the shear bearing capacity with the same cross section area of the rectangular column were similar, t-shaped cross section, l-shaped biggest difference, shear bearing capacity drops is the largest. [5] research shows that: L, T, 10 column shear bearing capacity of node is more effective than with the same cross section of the rectangular column node low 33%, 17.5% and 33% respectively, and used in rectangular column frame node shear calculation formula is not suitable for special-shaped column nodes. In high intensity area control structure with special-shaped columns is the height of the parameter is not just the column axial compression ratio, but the node area strength.
3　构造措施
3 construction measures
　　
　　异形柱的受力情况复杂，结构延性相对较差，单纯依靠目前的程序计算配筋尚难满足结构抗震的延性要求，因此必须加强构造措施，从概念出发，保证结构具有足够的安全度。
Force of the special-shaped columns is complex, the relatively poor ductility of structure, relying on the current application of reinforcement calculation is difficult to satisfy the demands of structure seismic ductility, so must strengthen the construction measures, starting from the concept, to ensure that the structure has enough safety.
　　3．1结构平面布置
3.1 structure layout
　　异形柱框架应设计成双向刚接梁柱抗侧力体系，根据结构平面布置和受力特点，可设计成部分异形柱部分矩形柱的形式，特别注意在受力复杂部分采用矩形柱。平面布置宜使结构平面刚度均匀对称，尽量控制或减小扭转效应：竖向布置注意体型力求简单规则，避免过大的外挑内收，避免楼层刚度沿竖向突变；柱网尺寸不易过大，一般不超过6m，柱矩大梁高也大，一方面建筑净空难以满足要求，另一方面柱承受的轴力也大，轴压比高，于抗震不利。为保证梁板对异形柱节点的约束，宜采用现浇楼盖。
Special-shaped columns frame should be designed as a two-way just answer Liang Zhukang lateral force system, according to the structure layout and mechanical characteristics, can be designed as part of the special-shaped columns section in the form of a rectangular column, special attention to in the complex loading using rectangular column. Layout appropriate uniform plane stiffness symmetry and try to control or reduce the reverse effect: vertical arrangement pay attention to the body to simple rules, avoid excessive outside carry adduction, avoid floor along the vertical stiffness mutation; Column grid size not too big, generally no more than 6 m, high column moment girder is big also, architectural headroom is difficult to meet the requirements on one hand, on the other hand column under axial force is big, high axial compression ratio, the seismic unfavorable. In order to ensure the beam slabs of special-shaped column node constraints, appropriate USES cast-in-place floor.
　　3．2轴压比及柱配筋
3.2 axial compression ratio of column reinforcement
　　对于柱而言，控制其延性的因素很多，不管对矩形柱还是异形柱，轴压比无疑是最重要的控制条件之一，其侧移延性比随着轴压比的增大而急剧下降，对异形柱更应从严控制。这可以通过控制柱距、采用轻质墙体、优化结构平面布置改善。柱肢端承受梁传来的集中荷载，局部压应力大，可设置暗柱。曹万林等《钢筋混凝土带暗柱异形柱抗震性能试验及分析》表明：带暗柱异形柱与普通异形柱相比，承载力及延性和耗能能力有显著提高。
For column, there are many factors which can control its ductility, whether for rectangular column or special-shaped columns, axial compression ratio is undoubtedly one of the most important control condition, the lateral ductility ratio fell sharply, with the increase of axial compression ratio of special-shaped columns should be strictly controlled. This can be achieved by control column space, use of lightweight wall layout improvement, optimization of structure. Column from acra beams under concentrated load, local compression stress is large, dark column can be set up. Cao Wanlin etc. The seismic performance of reinforced concrete special-shaped columns with dark column test and analysis show that the special-shaped column with dark column compared with the ordinary special-shaped columns, the bearing capacity and ductility and energy dissipation capacity has improved significantly.
　　异形柱截面的剪力中心与截面形心不重合，剪应力的存在使柱肢先于普通矩形柱的剪压构件出现裂缝，产生腹剪破坏，导致柱脆性显著，延性普遍低于矩形柱。而且柱截面可能出现单纯翼缘受压，此时柱的延性最差，因此需要进一步提高异形柱的抗剪能力。除此之外，尽量避免短柱的出现，对剪跨比小的短柱要采取相应的加强措施，以免形成薄弱环节。
Special-shaped columns section of the shear center and the section centroid is not coincidence, the existence of the shear stress of column limb ahead of ordinary rectangular column shear component cracks, generate shear failure, lead to post brittleness, ductility is generally lower than the rectangular column. And compression of column section may appear simple flange, the ductility of the column's worst right now, so you need to further improve the shear capacity of special-shaped columns. In addition, to avoid the occurrence of short column, the short column shear span ratio lower are the corresponding strengthening measures, so as to avoid formation of weak links.
　　3．3节点构造
3.3 joint structure
　　
　　节点已经成为异形柱结构的薄弱环节，考虑到节点处钢筋的锚固以及保证节点区混凝土浇筑的质量，柱钢筋数量不宜过多且直径不宜过大。
Node has become the weak link of special-shaped column structure, considering the node reinforcement anchorage and guarantee the quality of node area concrete pouring, column number is unfavorable and overmuch and diameter steel shoulds not be too big.
　　
　　4　工程实例
4 engineering instance
　　
　　长沙市某住宅楼长24.7m，宽14.5m,建筑面积3575m2左右，地上架空层一层，层高4.5m，住宅十一层，层高3.0m，最大建筑高度为39.0m，平面图见图1。该工程抗震设防烈度为6度，设计基本地震加速度为0.05g，设计地震分组为第一组，场地类别Ⅱ类。采用异形柱框架——剪力墙结构，剪力墙抗震等级为三级，异形柱框架抗震等级为三级。采用SAIWE程序分析，各层间位移角见图2，满足规范对层间位移的规定；同时重视抗震概念设计，加强构造措施。目前已竣工验收交付使用，经观察结构整体状况良好。
A residential building in changsha city is 24.7 m long, 14.5 m, building area of 3575 m2, stilt floor layer on the ground, the height 4.5 m, residential 11 layer, the height 3.0 m, the largest building height is 39.0 m, the floor plan as shown in figure 1. The engineering seismic fortification intensity is 6 degrees, design basic earthquake acceleration of 0.05 g, design earthquake group is the first group, site category Ⅱ class. With frame - shear wall structure with special-shaped columns, the shear wall seismic grade for level 3, special-shaped column frame aseismic grade 3. SAIWE program analysis, by using the interlayer displacement Angle as shown in figure 2, and meet the specifications of the provisions of the interlayer displacement; At the same time attaches great importance to the seismic conceptual design, to strengthen the construction measures. Now consign is used, the final acceptance of the observed structure overall in good condition.
　　
　　5　结语
5 conclusion
　　
　　异形柱结构具有广阔的应用前景，但其受力性能具有自己的独特性，目前仍需要进一步研究以完善设计理论，开发更适用的设计软件，提高工程设计效率，便于推广运用。
Special-shaped column structure has broad application prospects, but its mechanical performance has its own uniqueness, still needs further research to perfect the design theory, more suitable design software development, improve the efficiency of engineering design, easy to promote.