首页 朱明之关于建筑-公众号 笔记《这可能是奠定美国PC抗震设计体系的一次实验》

笔记《这可能是奠定美国PC抗震设计体系的一次实验》

本文介绍了美国在1999年开展的一项关于预制混凝土结构抗震设计的研究及其验证实验。
从文章内容看,美国的混凝土装配式建筑因为设计规范不完善,也经历了一段时间的“等同现浇”,但是,这种基于等同现浇的设计明显缺乏市场竞争力。于是预制行业协会就牵头搞了这个课题,其目的主要是形成具有市场竞争力的连接方式,并开发配套预制装配式结构的设计规范-基于位移的分析方法。
作为整个课题基本结题的验证性实验,从实验节点及工法的设置上,可以看到美国预制体系是完全向着干式连接+预应力的方向在发展。通过新西兰及其它一些零星视频可以看出,这个实验的最终成果已经普遍被应用在高地震烈度区域。
建筑业和医疗行业有个类似的地方,就是互相不认可其它医院的检查报告。美国是家三甲医院,基于其行业地位,应该有不少二甲或者社区医疗机构对他们的检查报告还是接受的……

An Overview of the PRESSS Five-Story Precast Test Building

PRESSS五层预制试验大楼概述


作者:

At the culmination of the PRESSS (Precast Seismic Structural Systems) research program, a 60 percent scale five-story precast/prestressed concrete building will be tested under simulated seismic loading. This paper describes the prototype buildings used for design and the structural features of the test building. The buildings were designed using the direct displacement based approach, which is able to take advantage of the unique properties of precast/prestressed concrete using dry jointed construction. The test building incorporates four different seismic frame systems in one direction,and a jointed shear wall system in the orthogonal direction. Pretopped double tees are used on three floors, while the other two floors are constructed using topped hollow-core slabs. A major objective of the test program is to develop design guidelines for precast/prestressed concrete seismic systems that are appropriate for use in various seismiczones. These design guidelines can then be incorporated into the appropriate building codes.

PRESSS(预制地震结构系统)研究项目的高潮,一个60%规模的五层预制/预应力混凝土建筑将在模拟地震荷载下进行测试。本文介绍了用于设计的原型建筑和试验建筑的结构特点。建筑的设计采用了直接基于位移的方法,这能够利用预制/预应力混凝土的独特性能使用干接缝施工。试验建筑在一个方向上包含四个不同的抗震框架体系,在正交方向上包含一个节理剪力墙体系。三层使用了预顶部双t型,而其他两层使用顶部空心板。该测试计划的主要目标是为预制/预应力混凝土抗震系统制定设计指南,以适用于不同的地震带。这些设计准则可以被纳入适当的建筑规范。


The Precast Seismic Structural Systems (PRESSS) program has been in progress for ten years, with the final phase of the program well underway. PRESSS,sponsored by the National Science Foundation (NSF), Precast/Prestressed Concrete Institute (PCI) and Precast/Prestressed Concrete Manufacturers Association of California, Inc. (PCMAC), has coordinated the efforts of over a dozen different research teams across the United States to improve the seismic performance of precast/prestressed concrete buildings. In the context of this paper,“buildings” refer to low- and high-rise buildings such as office buildings, parking structures, hotels, hospitals, multi-family housing, and other special structures. However, bridges and transportation structures are excluded.Since the very beginning of the PRESSS program, all of the research teams involved in the program have focused their sights on two primary objectives:

预制地震结构系统(presss)项目已经进行了10年,项目的最后阶段正在顺利进行。PRESSS,由国家科学基金会(NSF)、预制/ (PCI)和预制预应力混凝土研究所/预应力混凝土制造商协会加州Inc . (PCMAC),协调的努力了十几个不同的研究团队在美国提高预制、预应力混凝土建筑物的抗震性能。在本文的语境中,建筑是指低层和高层建筑,如办公楼、停车场结构、酒店、医院、多户住宅等特殊结构。但是,桥梁和运输结构不包括在内。自新闻项目开始以来,所有参与该项目的研究团队都将目光集中在两个主要目标上:

• To develop comprehensive and ra- tional design recommendations needed for a broader acceptance ofprecast concrete construction in different seismic zones.

制定全面和合理的设计建议,使预制混凝土结构在不同的地震带得到更广泛的接受。

• To develop new materials, concepts,and technologies for precast concrete construction in different seismic zones.

为不同地震带的预制混凝土建筑开发新材料、新概念和新技术。

Fig. 1. Prototype building with pretopped double tees. Note: 1 ft = 0.3048 m.

Fig. 2. Prototype building with topped hollow-core slabs. Note: 1 ft = 0.3048 m; 1 in. = 25.4 mm


The first and second phases of the PRESSS program have been described by Priestley in the PCI JOURNAL.1The third phase consists of the seismicdesign and analysis of a five-story precast/prestressed concrete building using dry jointed construction. A portion of this building will be built at 60 percent scale and tested. The purposeof this paper is to present an overview of the test building, describe the major features of the structural systems investigated and offer some thoughts on the practical implications of the test results.

Priestley在PCI杂志上描述了PRESSS计划的第一和第二阶段。第三阶段包括使用干接缝结构的五层预制/预应力混凝土建筑的抗震设计和分析。该建筑的一部分将以60%的规模建造并进行测试。本文的目的是介绍测试建筑的概况,描述所调查的结构系统的主要特征,并提供一些对测试结果的实际影响的想法。


PRESSS III PROGRAM OBJECTIVES

PRESSS III 计划目标

Academic research is often focused solely on improving the performance of existing structural systems. While history confirms that this is a worthy goal,the reality of the construction market place is that improved performance of a system will generally not be accepted unless it also results in a lower cost.Thus, the PRESSS Phase III research team, comprising researchers and industry advisory group members, has kept in mind that in addition to improving performance, cost effectiveness of the resulting systems is crucial.The PRESSS Phase III test program is based on the design of two prototype five-story precast office buildings, 100 x 200 ft (30.5 x 61 m) inplan, with 12 ft 6 in. (3.81 m) story heights. Both buildings use frames to resist lateral loads in the longitudinal direction and shear walls to resist lateral loads in the transverse direction.The first building, shown in Fig. 1,uses pretopped double tees to span between a central gridline and the perimeter of the building. The second prototype building, shown in Fig. 2, is based on a topped hollow-core slab floor system. For simplicity, the same floor system was assumed at the roof as well as at each floor.

学术研究往往只关注于改善现有结构系统的性能。虽然历史证明这是一个有价值的目标,但建筑市场的现实情况是,提高系统的性能通常不会被接受,除非它也能降低成本。因此,由研究人员和行业咨询小组成员组成的press第三阶段研究小组牢记,除了提高性能外,系统的成本效益是至关重要的。第三阶段的测试计划是基于两个五层预制办公大楼的原型设计,平面100 x 200英尺(30.5 x 61米),12英尺6英寸。(3.81米)层高。这两个建筑都使用框架来抵抗纵向的横向荷载和剪力墙来抵抗横向荷载。第一个建筑,如图1所示,在中央网格线和建筑的周长之间使用预盖的双三通。第二个原型建筑,如图2所示,是基于顶部空心板楼板系统。为了简单起见,屋顶和每一层都采用了相同的楼层系统。


The size of the testing laboratory limited the test building to 30 x 30 ft(9.14 x 9.14 m) in plan. Rather than designing the test building to resist just its own inertial loads, the inertial loads of the prototype buildings were calculated and then scaled down to represent the scale of the test building.This gives a more accurate picture ofthe demand that a practical building configuration would be subjected to,without exceeding the space limitations of the laboratory. The test building will be subjected to increasingly larger seismic demands that represent low service level earthquakes, moderate (Zone 2 design level) earthquakes and design level earthquakes beyond those required for Zone 4.The ultimate objective of the research, however, is not the test itself,but the design recommendations that will result from the testing program.Because there are so many different combinations of systems included in the test building, it does not represent the most economical way to implement these new structural systems. The final design recommendations are the key to obtaining improved performance of the proposed systems at a competetive cost in practical applications.

测试实验室的大小限制了测试建筑的平面尺寸为30 x 30英尺(9.14 x 9.14米)。不仅设计测试建筑来抵抗它自己的惯性负载,原型建筑的惯性负载被计算,然后按比例缩小,以代表测试建筑的规模。这提供了一个更准确的要求,实际的建筑配置将受到,而不超过实验室的空间限制。测试大楼将承受越来越大的地震需求,代表低服务级别地震,中(2区设计级别)地震和设计级别地震超过4区要求。然而,研究的最终目标不是测试本身,而是测试程序将产生的设计建议。因为在测试建筑中包含了许多不同的系统组合,所以它并不代表实现这些新的结构系统的最经济的方式。最终的设计建议是在实际应用中以具有竞争力的成本获得所建议系统的改进性能的关键。


Fig. 3. Current code design choices for precast systems.


EXISTING DESIGN CODES

现有的设计规范

During the life of the PRESSS program, there have been significant developments in the model codes2 , 3 that provide some guidance to design engineers wanting to implement precast seismic systems in their buildings. As shown in Fig. 3, current codes allow precast seismic systems that either emulate monolithic concrete or rely on the unique properties of precast concrete (i.e., jointed, dry construction).While jointed construction is allowed by the code, the focus of the prescriptive code provisions has been on emulation of monolithic concrete, largely because a consistent set of design recommendations for jointed precast systems have not been developed. Jointed systems can only be used if they are justified by test data on a case-by-case basis. The PRESSS program goes a step further by focusing its efforts almost exclusively on systems that relyon and take advantage of the uniqueproperties of precast concrete. The intention is then to develop a consistentset of design recommendations for jointed precast systems that can be used to update existing code provisions.

在PRESSS项目的生命周期中,模型规范2、3有了重大的发展,为想要在建筑中实施预制抗震系统的设计工程师提供了一些指导。如图3所示,目前的规范允许预制抗震系统模拟整体混凝土或依赖预制混凝土的独特特性(即接缝、干结构)。虽然规范允许接缝施工,规范规定的重点一直是在模拟整体混凝土,很大程度上是因为一套一致的设计建议的接缝预制系统还没有开发出来。联合系统只能在逐个案例的测试数据证明其正确性的情况下使用。PRESSS项目更进一步,几乎完全专注于依赖和利用预制混凝土的独特性能的系统。目的是为联合预制系统开发一套一致的设计建议,可用于更新现有的规范规定。


Force Based Design

强度设计

Seismic design in current codes is exclusively force based. That is, a designer uses elastic properties to determine an elastic base shear, which is then divided by a force-reduction factor R to obtain the design base shear.The value of R depends largely on the nominal ductility capacity of the system chosen, which is somewhat arbitrary and varies between codes. While maximum structural displacements must satisfy certain limits, they are in most cases based on elastic structural properties and are amplified by factors intended to approximate the post-elastic response. This approach has some significant drawbacks, as discussed by Priestley ,4 especially for precast concrete. Despite these difficulties, it will continue to be the legal design procedure for at least the foreseeable future.In Force Based Design, there are two main ways that a designer can reduce the cost of a seismic system. Both methods depend on reducing the design loads because for consistent detailing, a lower force results in a lower cost. In the first method, a larger R factor is used to reduce the design baseshear. For frames, the R value can be maximized by detailing the structure as a Special Moment-Resisting Frame (UBC R = 8.5, NEHRP R = 8) rather than an Intermediate Moment-Resisting Frame (UBC R = 5.5, NEHRP R =5). The second method consists of using a longer period to reduce the design base shear. This method forms the basis of recommendations proposed by the PCI AdHoc Committee Report on Precast Walls.5

现行规范的抗震设计完全是基于力的。也就是说,设计者利用弹性特性来确定弹性基底剪力,然后除以减力系数R得到设计基底剪力。R的值很大程度上取决于所选系统的标称延性能力,该标称延性能力是任意的,并且在不同的规范中有所不同。虽然最大结构位移必须满足一定的限制,但在大多数情况下,它们是基于弹性结构特性,并被拟近似弹性后响应的因素放大。这种方法有一些显著的缺点,如Priestley,4所讨论的,特别是对于预制混凝土。尽管存在这些困难,但至少在可预见的未来,这仍将是法律设计程序。在基于力的设计中,设计者有两种主要的方法来降低地震系统的成本。这两种方法都依赖于减少设计载荷,因为为了保证细节的一致性,更低的力可以降低成本。在第一种方法中,采用较大的R系数来减小设计基剪。对于框架,R值可以通过将结构详细描述为一个特殊的抗弯矩框架(UBC R = 8.5, NEHRP R = 8)而不是中间的抗弯矩框架(UBC R = 5.5, NEHRP R =5)来最大化。第二种方法是使用较长的周期来减少设计基底剪力。该方法是PCI预制墙专案委员会报告建议的基础。


Fig. 4. Test building – Level 1 floor plan. Note: 1 ft = 0.3048 m.

Fig. 5. Test building – Level 4 floor plan. Note: 1 ft = 0.3048 m.


Frame Systems

框架系统

Ordinary Moment-Resisting Frames(OMRF) are not permitted in moderate and high seismic zones (UBC Zones 2,3, and 4) because of their fundamental lack of ductile behavior. For seismic design using frames in moderate seismic zones, a designer has a choice between using an Intermediate Moment Resisting Frame (IMRF) or a Special Moment-Resisting Frame (SMRF).Table 1 compares the detailing requirements of the two frame types. In high seismic zones, only SMRF frames are permitted .The appearance of a choice is deceptive because the SMRF is almost invariably the most cost effective frame solution. This is so because the design loads on an SMRF are 35 to 40 percent lower, primarily due to the higher R factor. Also, the period of an SMRF system is slightly longer than that of an IMRF system for the same building, due to the lower frame stiffness. This, too, means that the SMRF design load is lower. These benefits easily outweigh the extra costs of the slightly more stringent detailing requirements for the SMRF.In summary, therefore, it is fromthis perspective of the need for ductile performance and cost effective design that only SMRF systems were chosen for the PRESSS III test building.These systems are appropriate, and cost effective, in all seismic zones.

普通抗弯矩框架(OMRF)不允许在中震区和高震区(UBC区2、3和4),因为它们根本缺乏延性行为。在中等震区使用框架进行抗震设计时,设计者可以选择使用中间抗弯矩框架(IMRF)或特殊抗弯矩框架(SMRF)。表1比较了两种框架类型的详细要求。在高震区,只允许使用SMRF框架。这种选择的表面是具有欺骗性的,因为SMRF几乎总是最经济有效的框架解决方案。这是因为SMRF的设计负载降低了35%到40%,主要是由于较高的R系数。同样,由于框架刚度较低,SMRF系统的周期略长于IMRF系统。这也意味着SMRF的设计负载更低。这些好处轻松地超过了SMRF更严格的细节要求所带来的额外成本。综上所述,正是从延展性性能和成本效益设计的需求角度出发,PRESSS III测试大楼只选择了SMRF系统。这些系统适用于所有的地震带,并且具有成本效益。

Fig. 6. Prestressed frame elevation. Note: 1 ft = 0.3048 m; 1 in. = 25.4 mm.

Fig. 7. Tension-Compression Yielding (TCY) frame elevation. Note: 1 ft = 0.3048 m;1 in. = 25.4 mm.

Fig. 8. Hybrid frame interior joint (transverse reinforcement not shown for clarity). 

Note: 1 ft = 0.3048 m; 1 in. = 25.4 mm.

Fig. 10. Pretensioned frame interior joint (transverse reinforcement not shown for clarity). 

Note: 1 ft = 0.3048 m; 1 in. = 25.4 mm.


Wall System

墙体系统

Wall systems designed under current codes are described as either loadbearing or non-loadbearing walls.Since non-loadbearing walls are usually more ductile than loadbearingwalls, the UBC R factor for them is 18 percent more than that for loadbearingwalls. This results in an 18 percent decrease in the design base shear and aconcomitant reduction in the cost for non-loadbearing wall systems that are otherwise identical to their loadbearing wall counterparts.It is fairly straight forward to lengthen the building period in a precast shear wall system by providing vertical joints between the panels that make up a wall (see PCI Ad Hoc Committee Report on Precast Walls5).Thus, by providing a jointed shearwall, the design forces are reduced, resulting in a reduced building cost.

根据现行规范设计的墙体系统可分为承重墙体和非承重墙体。由于非承重墙通常比承重墙更有韧性,非承重墙的UBC R系数比承重墙的UBC R系数高出18%。这使得设计基础剪力降低了18%,并相应地降低了非承重墙系统的成本,而非承重墙系统在其他方面与承重墙系统相同。在预制剪力墙系统中,通过在组成墙的板之间提供垂直连接来延长建筑周期是相当直接的(见PCI预制墙特设委员会报告5)。因此,通过提供一个接缝剪力墙,减少了设计力,从而降低了建筑成本。


Results of Force Based Design

基于力的设计结果

It should be noted that, although improving ductility and lengthening the system period reward buildings with lower design loads, the magnitude ofthe reduction reflects only poorly thetrue advantages that well-designed precast systems offer. For example,the design base shear for the prototype building using force based design inaccordance with the 1997 UBC (Zone4) is as follows:Frame direction (Tn = 0.67 seconds)Design base shear = 2248 kips (10000 kN)Wall direction (Tn = 0.48 seconds)Design base shear = 4889 kips (21746 kN)These values reflect the advantages of a ductile system (i.e., R = 8.5 for frames) and a lengthened period for the shear wall building which is comprised of jointed wall panels. The design base shear for an equivalent cast in-place frame system would be identical, since the elastic stiffnesses of a precast frame and a cast-in-place frame are similar. However, the elastic period for an equivalent, non-jointed,cast-in-place wall would be substantially shorter than the jointed wall period. Except in cases where the maximum base shear governs, a shorter period would result in a higher baseshear.

应该注意的是,尽管提高延性和延长系统周期会使建筑具有更低的设计负荷,但减少的幅度仅反映出良好设计的预制系统提供的真正优势。例如,为原型设计基底剪力对建筑使用基于力设计1997年哥伦比亚大学(Zone4)如下:框架方向(Tn = 0.67秒)设计基底剪力= 2248kips(10000 kN)墙方向(Tn = 0.48秒)设计基底剪力= 4889kips(21746 kN)这些值反映韧性的优点系统(即R = 8.5 for frames)和一个延长期限的剪力墙建筑组成的有节的壁板。由于预制框架和现浇框架的弹性刚度相似,所以等效现浇框架体系的设计基础剪力是相同的。然而,等效的无接缝现浇墙的弹性周期将大大短于有接缝墙的周期。除了在最大基底剪力支配的情况下,较短的周期会导致较高的基底剪力。

While the systems included in the test building are expected to be costeffective even using force based design, the PRESSS III test building adopts an alternative design procedure that more efficiently incorporates the advantages of well-designed precast systems. As will be discussed below, a further reduction to design base shear is achieved, providing substantial cost savings for precast buildings in all seismic zones.

即使采用基于力的设计,包括在测试大楼内的系统也有望达到成本效益,而presss III测试大楼采用了另一种设计程序,更有效地结合了设计良好的预制系统的优点。下文将讨论,进一步减少了设计基础剪力,为所有地震带的预制建筑节省了大量费用。

Fig. 9. Hybrid framehysteresis loop(from Ref. 6).

Fig. 11. Pretensioned frame hysteresis loop (from Ref. 7).


DESIGN OF PRESSS III TEST BUILDING

PRESSS III实验楼设计

The PRESSS Phase III test building is not intended to create new design concepts, but rather to examine the suitability of design concepts created in earlier phases of the PRESSS program or other precast concrete research. One criterion used in determining which systems would be included in the test building was that the concept had to have been experimentally validated through component tests.The complete building test is important because it addresses many questions of design and constructability,which do not arise in component tests.Also, the behavior of a complete, statically indeterminate system involves many features, including verification of seismic design methods that do not occur in statically determinate component tests.

第三阶段的测试建筑并不是为了创造新的设计概念,而是为了检验在press项目早期阶段或其他预制混凝土研究中创造的设计概念的适用性。在确定哪些系统将包括在测试建筑中使用的一个标准是,这个概念必须通过组件测试进行实验验证。完整的构建测试很重要,因为它解决了许多在组件测试中不会出现的设计和可施工性问题。此外,一个完整的、静不定系统的行为包括许多特征,包括在静定构件试验中不发生的抗震设计方法的验证。


The specific objectives of the test are to:

测试的具体目标是:

• Validate a rational design procedure for precast seismic structural systems.

验证预制抗震结构体系的合理设计程序。

• Provide acceptance of prestressing/post-tensioning of precast seismic systems.

提供预制地震系统的预应力/后张拉验收。

• Provide experimental proof of overall building performance under seismic excitation.

为建筑物在地震作用下的整体性能提供实验证明。

• Establish a consistent set of design recommendations for precast seismic structural systems.

为预制抗震结构体系建立一套一致的设计建议。

The PRESSS III test building consists of frames in one direction and a shear wall in the other, as shown in Figs. 4 and 5. The floor system used in the first three levels is pretopped double tees, and the top two levels consist of topped hollow-core slabs. Those choices were made in order to include the two major structural framing systems commonly used in precast construction today.

PRESSSIII试验建筑由一个方向的框架和另一个方向的剪力墙组成,如图4和5。在前三层使用的地板系统是双T板,而顶部两层由空心板组成。这些选择是为了包括两种主要的结构框架系统,常用在今天的预制建筑。

The building will be tested in both the frame and wall directions independently under simulated seismic loads that represent earthquakes up to 50 percent stronger than Zone 4 design level earthquakes recognized in codes.During the loading in each direction,two independently controlled actuatorsat each floor level will prevent torsion.

在模拟地震荷载下,该建筑将在框架和墙体两个方向独立进行测试,模拟地震荷载代表的地震强度比规范中认可的4区设计级地震高50%。在每个方向的加载过程中,每个楼层的两个独立控制的执行机构将防止扭转。

Fig. 12. TCY gap frame interior joint (transverse reinforcement not shown for clarity). 

Note: 1 ft = 0.3048 m; 1 in. = 25.4 mm.

Fig. 13. TCY gap frame hysteresis loop (from Ref. 7).



Frame Connection Systems

框架连接系统

Four different types of ductile connection systems are used in the PRESSS III test building frames. They are:

建筑框架采用四种不同类型的延性连接系统。它们是:

• Tension-Compression Yielding(TCY) gap connection

拉压屈服(TCY)间隙连接

• TCY connection

TCY连接

• Hybrid connection

混合连接

• Pretensioned connection

预张连接

The first three types of connections consist of multistory columns and single-bay beams, and are appropriate for floor-by-floor construction. The pretensioned connection uses multi-bay beams and single-story column sand is appropriate for “up-and-out”construction.The hybrid connection and pretensioned connection are used in one seismic frame, referred to as the PreTensioned Frame, and the remaining two connections are adopted in the other seismic frame, known as theTension-Compression Yielding Frame.These two frame elevations are shownin Figs. 6 and 7, respectively. The amounts of energy dissipation and residual displacement vary among the four connections, allowing a designer to control seismic behavior of the structure with an appropriate choice of connection system.

前三种连接方式由多层柱和单隔梁组成,适用于逐层施工。预应力连接采用多隔间梁,单层柱,适用于自下而上的施工。其中一榀抗震框架采用了混合连接和预张拉连接,另一榀抗震框架采用了两种连接方式。这两个框架标高分别如图6和图7所示。四种连接的能量耗散和残余位移量各不相同,允许设计师通过选择合适的连接系统来控制结构的抗震性能。

Fig. 15. TCY frame hysteresis loop (from Ref. 7).

Fig. 14. TCY frame interior joint (transverse reinforcement not shown for clarity). 

Note: 1 ft = 0.3048 m; 1 in. = 25.4 mm.

Hybrid Frame

混合框架

The hybrid connection was developed during the last phase of a multi year project at the National Institute of Standards and Technology (NIST).6 The hybrid frame interior joint is shown in Fig. 8. The beams are connected to multistory columns by unbonded post-tensioning strands that run through a duct in the center of the beam and through the columns. Mildsteel reinforcement is placed in ducts at the top and bottom of the beam,through the column, and is grouted. It yields alternately in tension and compression and provides energy dissipation (see Fig. 9). The amount of mildsteel reinforcement and post-tensioning steel are balanced so that the frame recenters after a major seismic event. The exterior joint of the Hybrid Frame uses a “stub” beam that contains the multistrand anchor. This is only required due to the scale of the test building. Research 8 indicates that anchors located within the joint may actually improve joint performance. 

这种混合连接是在美国国家标准与技术研究所(NIST)一个多年项目的最后阶段开发的。6混合框架内节点如图8所示。梁通过无粘结后张拉钢绞线与多层柱连接,钢绞线穿过梁中心的管道和柱子。低碳钢钢筋被放置在梁的顶部和底部的管道中,穿过柱,并灌浆。它在拉和压交替屈服并提供能量耗散(见图9)。低碳钢钢筋和后张钢筋的数量是平衡的,以便在一次重大地震事件后框架中心。HybridFrame的外部接头使用包含多股锚的短梁。这只是由于测试建筑的规模所需要的。研究表明,位于关节内的锚实际上可以提高关节的性能。


PreTensioned Frame

预应力框架

The PreTensioned frame, named soas to differentiate it from just any frame constructed with pretensioned members, is intended to be used for construction where the most economical method consists of using one-story columns with multi-span beams.Long, multi-span beams are cast in normal pretensioned casting beds,with specified lengths of the pretensioning strand debonded.These beams are then set on one story columns with the column reinforcing steel extending through sleeves in the beams. Reinforcing bar splices ensure the continuity of the column above the beam, as shown in Fig. 10. As the frame displaces laterally, the debonded strand remains elastic. While the system dissipates relatively less energy than other systems7,9,10 (see Fig. 11), it recenters the structure after a major seismic event.

预应力框架,命名为soa,以区别于任何由预应力构件构造的框架,旨在用于使用最经济的方法包括使用单层柱和多跨梁的建筑。长、多跨梁在正常的预张拉浇筑床上浇筑,预张拉钢绞线脱粘指定长度。然后,这些梁被安置在单层柱上,柱的钢筋通过梁的套管延伸。钢筋接梁保证了梁上柱的连续性,如图所示10. 当框架横向位移时,脱粘链仍保持弹性。虽然该系统耗散的能量相对较少,比其他系统7,9,10(见图11),它会在一次大地震后重新调整结构

TCY Gap Frame

The TCY gap frame addresses the problem of frame beam elongation in an innovative way. The beams are erected between columns leaving a small gap between the end of the beam and the face of the column. Only the bottom portion of this gap is grouted to provide contact between the beam and column (see Fig. 12). Centered on this bottom grout region, post-tensioning bars clamp the frame together. At the top of the beam, mild steel reinforcement is grouted into sleeves that extend the length of the beam and through the column.The reinforcing steel is carefully debonded for a specified length at the gap so that it can yield alternately in tension and compression without fracture. Since the gap opens on one side of the column as it closes on the other side by an equal amount, the length of the frame does not change, even as the connection yields. The TCY gap connection tested in a PRESSS Phase II research program 7 used a coupler to splice the reinforcing steel through the column, rather than the sleeve through the column shown in Fig. 12.The hysteresis loop obtained in PRESSS Phase II shows that this system 7 was performing as expected, and dissipated significant energy, until premature failure of the reinforcing bar couplers at the top of the beam failed the connection (see Fig. 13).The possibility of a premature failure of this type is eliminated by the sleeved connection.

TCY间隙车架以创新的方式解决了框架梁的伸长问题。梁竖立在柱子之间,在梁的末端和柱子的表面之间留下一个小间隙。只有这个缝隙的底部被灌浆以提供梁和柱之间的接触(见图12)。以底部灌浆区域为中心,后张筋将框架夹在一起。在梁的顶部,软筋灌入套管中,套管延伸梁的长度并贯穿整个柱。在缝隙处,钢筋被小心地脱粘到一定长度,以便在拉和压时交替屈服而不断裂。由于间隙在柱的一侧打开,而在另一侧闭合,因此即使连接产生,框架的长度也不会改变。在PRESSS ii研究项目7中测试的TCY间隙连接使用耦合器将钢筋连接到柱上,而不是图12中所示的套筒连接到柱上。在第II阶段获得的迟滞回线表明,该系统7按预期执行,并耗散了显著的能量,直到梁顶部的钢筋耦合器过早失效,导致连接失效(见图13)。通过套筒连接消除了这种类型过早失效的可能性。


TCY Frame

The TCY frame connection attempts to model a traditional tension/compression yielding connection,similar to what is used in cast-in-place construction. However, rather than distributed yielding over a finite plastic hinge length, yielding is concentrated at the connection. To ensure that the beam reinforcement that provides moment strength and energy dissipation does not fracture prematurely at this concentrated yielding location, it is debonded over a short length at the beam-to-column interface (see Fig. 14).This type of connection was also tested in PRESSS Phase II research program ,7 , 9 , 1 0 where it showed slightly pinched hysteretic behavior due to vertical slip at the beam-to-column interface (see Fig. 15). Although this type of behavior may also occur in the PRESSS III test building, the connection has been included since it is conceptually very similar to traditional methods of construction. If verticalslip starts to occur at the ends of these beams, steel corbels will be installed during the test so that slip does not adversely affect the overall test results.

TCY框架连接试图模拟传统的拉/压屈服连接,类似于现浇施工中使用的连接。然而,屈服不是分布在有限塑性铰长度上,而是集中在连接处。为了确保提供弯矩强度和能量耗散的梁筋不会在这个集中屈服位置过早断裂,它在梁-柱界面短时间内脱粘(见图14)。在第二阶段的研究中也对这种连接进行了测试,在梁-柱界面处,由于竖向滑移,这种连接表现出轻微的挤压滞回特性(见图15)。虽然这种类型的行为也可能发生在压力III测试建筑,连接已经包括,因为它是概念上非常类似于传统的建造方法。如果在这些梁的两端开始发生垂直滑移,将在测试期间安装钢梁,使滑移不会对整体测试结果产生不利影响。


Frame Columns

框架柱

The frame columns used for all systems contain both mild steel reinforcement and post-tensioning bars (seeFigs. 8, 10, 12 and 14). The post-tensioning bars are intended to represent the equivalent dead loads based on the prototype structure, but their inclusion in the test will also validate that this method of adding vertical load to aprecast column is an effective way to influence system performance.In addition, the columns in the prestressed concrete frame are pretensioned up to the fourth level of the building. This bonded prestressing economically adds strength to the columns, which are prevented from yielding using capacity based design.These details will validate the performance of pretensioned frame columns.

用于所有系统的框架柱包括软钢钢筋和后张筋(见图。8、10、12和14)。后张杆的目的是代表基于原型结构的等效恒载,但将其纳入试验也将验证这种在预制柱上添加竖向荷载的方法是影响系统性能的有效方法。此外,预应力混凝土框架的柱被预张拉到建筑的第四层。这种粘结预应力经济地增加了柱的强度,防止其屈服使用基于能力的设计。这些细节将验证预应力框架柱的性能。


Building Frame Choices

框架选型

While it was never intended that multiple connection types would be used on different floors or in different frames of the same building in practice,the PRESSS research team and industry advisors felt strongly that several different frame systems should be included in the test building. The objective was to provide designers with several alternatives using precast concrete;not just different ways of building conceptually similar systems (e.g., structural steel in Table 2), but systems with fundamentally different types of behavior that might be appropriate for different situations. This, as shown in Table2, will provide versatility using precast concrete that is not currently availableusing any other building material.In addition, by validating severaldifferent frame types, it is hoped thatfuture innovations can fit into the framework developed by the PRESSS research program, through component testing rather than requiring additional large-scale building tests.

虽然在实践中从未打算在同一栋建筑的不同楼层或不同框架中使用多种连接类型,但presss研究团队和行业顾问强烈认为,几个不同的框架系统应该包括在测试建筑中。我们的目标是为设计师提供几个使用预制混凝土的替代方案,不仅是用不同的方式建造概念上相似的系统(如表2中的结构钢),而且是具有不同行为类型的系统,可能适合不同的情况。如表2所示,预制混凝土将提供目前使用任何其他建筑材料都无法提供的通用性。此外,通过验证几种不同的框架类型,希望未来的创新可以适应presss 研究项目开发的框架,通过组件测试,而不是需要额外的大规模构建测试。


Wall System

For the past several years, the PCI Ad Hoc Committee on Precast Walls has been promoting precast shearwalls as seismic resisting systems for all seismic zones.5 This work has focused on “tuning” jointed walls to lengthen the structural period and reduce the design base shear forces. The focus was on evaluating elastic stiffness, without explicit consideration of ductility. Elastic forces were distributed so that sufficient resistance to overturning was provided by the gravity loads on the system.The PRESSS test building takes this concept one step further by considering the behavior of the jointed shearwall system when the wall lifts off and rocks, together with its effect on design forces. An appropriate level of hysteretic damping is added to the wall system through the connection devices located at the vertical joint between the wall panels.Due to limitations on the building size, imposed by the dimensions of the testing laboratory, only one jointed wall system is incorporated in the test building. Instead of limiting the lateral loads to those that could be resisted by the inherent gravity loads in the system, vertical unbonded post-tensioning is used to resist overturning in this wall system.U-shaped flexure plates (UFP), as tested in PRESSS Phase II,11 are used for vertical joint connection devices where damping is achieved by means of flexural yielding of the plates. The unbonded post-tensioning is designedto re-center the wall system when the load is removed so there will be noresidual drift after a design-level earthquake. Re-centering is ensured by relating the elastic capacity of the posttensioning system to the yield strength of the panel-to-panel connections.12 Fig. 16 shows the shear wall elevation, with unbonded posttensioning located at the center of each panel.The shear wall is expected to displacelaterally to approximately 2 percent story drift under a design-level earthquake. This is consistent with the drift limits specified in both the UBC2 and NEHRP provisions.3 This lateral displacement requires avertical panel-to-panel displacement of about 2 in. (51 mm) for the 9 ft(2.74 m) panel. Thus, the UFP connection shown in Fig. 17 was chosen forits ability to retain its force capacity through this large displacement. The post-tensioning was designed to be just at the point of yielding at 2 percent drift. Should the designer desire a smaller design story drift, or less energy dissipation, simpler panel connections could be used.

在过去的几年里,PCI预制墙特设委员会一直在推广预制剪力墙作为所有地震带的抗震系统。这项工作的重点是调整接缝墙,以延长结构周期和减少设计基础剪力。重点是评价弹性刚度,没有明确考虑延性。弹性力的分布使得系统上的重力载荷提供了足够的抗倾覆力。PRESSS测试建筑进一步考虑了这一概念,考虑了节理剪力墙系统的行为时,墙起裂和摇摆,以及其对设计力的影响。通过位于墙板之间垂直连接处的连接装置,将适当水平的迟滞阻尼添加到墙体系统中。由于建筑尺寸的限制,加上测试实验室的尺寸,只有一个接缝墙系统被纳入测试建筑。在该墙体系统中,竖向无粘结后张法用于抵抗倾覆,而不是将横向荷载限制在系统中固有重力荷载所能抵抗的范围内。u形弯曲板(UFP),在第二阶段的测试中,11用于垂直连接设备,通过弯曲屈服的板实现阻尼。无粘结后张拉是设计来重新中心时,墙体系统的荷载是消除,因此将没有残余的变形后,设计水平的地震。重新定心是通过将后张系统的弹性能力与面板到面板连接的屈服强度联系起来来保证的。12图16为剪力墙标高,无粘结后张拉位于每面板的中心位置。在设计级地震下,剪力墙的侧向位移预计为大约2%的楼层位移。这与UBC2和NEHRP规定的位移限制一致。这种横向位移要求面板对面板的垂直位移约为2英寸。(51毫米)为9英尺(2.74米)面板。因此,选择图17所示的upp连接,是因为它能够在大排量的情况下保持受力能力。后张拉的设计是刚好在2%漂移时的屈服点。如果设计者想要一个更小的层间位移,或更少的能量耗散,简单的面板连接可以使用。

Fig. 16. Elevation of jointed shear wall system. 

Note : 1 ft = 0.3048 m; 1 in.= 25.4 mm.

Fig. 17. Detail of U-shaped flexure plate. 

Note: 1 ft =0.3048 m; 1 in. = 25.4 mm.


DIRECT DISPLACEMENT BASED DESIGN

直接基于位移设计

As noted previously, Force Based Design represents the behavior of jointed precast systems poorly. The method relies on an initial elastic period, which is not only difficult to compute in a system whose flexibility resides largely in the connections, but also has little influence on the postelastic behavior of the structure. The R factors included in design codes are also not intended to be applied to systems, such as some of those used here,which do not emulate monolithic concrete structures. Thus, the results obtained by representing the seismic performance of precast systems using a Force Based Design approach are questionable.For this reason, the test building was designed using a more consistent Direct Displacement Based Design(DBD) procedure,4 in which the design is based directly on an inelastic target displacement and effective stiffness.The target structural displacement is determined from an allowable interstory drift permitted by design codes while the effective stiffness is approximated to the secant stiffness of the building corresponding to its expected fundamental mode of response. Use of both the elastic stiffness for determining in elastic structural displacementsand arbitrary reduction factors, as in Force Based Design, are completely eliminated in this design approach.

如前所述,基于力的设计代表了接缝预制系统的行为很差。该方法依赖于初始弹性周期,对于一个弹性主要集中在连接上的系统来说,初始弹性周期不仅难以计算,而且对结构的后弹性性能影响很小。设计规范中包含的因素也不打算应用于系统,例如这里使用的一些系统,它们不模拟整体混凝土结构。因此,通过使用基于力的设计方法代表预制系统的抗震性能所获得的结果是值得怀疑的。为此,试验建筑采用了更加一致的基于直接位移的设计(DBD)程序,该设计直接基于非弹性目标位移和有效刚度。目标结构位移是从设计规范允许的层间位移确定的,而有效刚度近似于与其期望的基本响应模态相对应的建筑的割线刚度。这种设计方法完全消除了使用弹性刚度来确定非弹性结构位移和任意折减系数作为基于力的设计。

Fig. 18. Flowchart showing Direct-Displacement Based Design method.


Direct Displacement Based Design Procedure

基于直接位移的设计程序

Direct Displacement Based Design(DBD) is a process that is intended to ensure that the structure reaches, but does not exceed, a target displacement selected by the designer, in response to a given ground motion. In this method the true hysteretic behavior is replaced by a linear system in which the stiffness is equal to the true secant stiffness and the viscous damping provides the same energy dissipation per cycle.The DBD design procedure, as adopted in the test building, is illustrated in Fig. 18. Once the target driftis chosen, the damping is estimated for the building using prior componenttest results. Representing the building with a SDOF system, the fundamental period corresponding to the target displacement is found from the displacement spectrum. The effective stiffnessis computed from the known mass and the estimated period.The design base shear is then obtained from the effective stiffness and target displacement. Member sizes and reinforcement are chosen to resist this base shear. The true physical properties of the members are used to generate a more refined, hysteretic, forced is placement curve. The effective damping is calculated from the hysteres is loop area and is checked against the assumed value. If they differ significantly, the process is repeated with a new value of assumed damping. This final step is only necessary because of the lack of information on global hesteretic damping forthe systems used in the test building.

直接基于位移的设计(DBD)是一个过程,旨在确保结构达到,但不超过设计者选择的目标位移,以响应给定的地面运动。在这种方法中,真滞回行为被一个线性系统代替,其中的刚度等于真正割刚度和粘滞阻尼提供相同的能量耗散每个周期。试验大楼采用的DBD设计流程如图18所示。一旦目标位移被选择,阻尼估计为建筑使用先验组件测试结果。用单自由度系统表示建筑物,目标位移对应的基周期由位移谱得到。有效刚度是根据已知质量和估计周期来计算的。由有效刚度和目标位移得到设计基底剪力。构件尺寸和钢筋的选择是为了抵抗这种基础剪力。真实的物理性质的成员是用来产生一个更精细的,滞后,力-位移曲线。从迟滞回线的面积计算出有效的阻尼,并根据假定的值进行校核。如果它们显著不同,则以一个新的假定阻尼值重复此过程。这最后一步是必要的,因为缺乏关于测试建筑中使用的系统的全局变滞阻尼的信息。

Fig. 19. Comparison of design base shears.


Results of Direct Displacement Based Design

基于直接位移的设计结果

For the PRESSS III prototype building, Direct Displacement Based Design resulted in a design base shear noticeably lower than would be used for force based design. For the prototype building, the design base shears are as follows:Frame direction:Design base shear = 1467 kips (6525 kN)Wall direction:Design base shear = 2223 kips (9888 kN)In the frame direction, this is 65 percent of the equivalent Force Based Design base shear, resulting in a substantial cost savings. In the wall direction,the savings are similar, even if the lengthened period is used in Force Based Design. The wall direction DBD base shear is just 45 percent of the equivalent Force Based Design value(see Fig. 19). Clearly, the improved performance of these systems can also result in substantial cost savings over traditional structural systems.

对于PRESSSIII原型建筑,直接基于位移的设计导致设计基础剪力明显低于基于力的设计。原型构建,设计基本剪如下:框架方向:设计基底剪力= 1467kips(6525 kN)墙方向:设计基底剪力= 2223kips(9888 kN)框架的方向,这是基于等效构件设计基底剪力的65%,导致大量节省成本。在墙体方向,即使在基于力的设计中使用延长的周期,节省也是类似的。墙体方向DBD基底剪力仅为基于等效力的设计值的45%(见图19)。显然,与传统的结构系统相比,这些系统性能的提高也可以节省大量成本。


TESTING SCHEDULE

The PRESSS III test building isunder construction in the Charles LeePowell Structural Laboratory of the University of California at San Diego,as of the publication date of thispaper. Following the completion ofthe building in April 1999, testing isscheduled to begin in May. Testing isexpected to be complete by July 1999,with analysis and reports to follow.The report on design recommendations is scheduled for completion byAugust 2000.

在这篇论文发表的时候,presss III测试大楼正在圣地亚哥加利福尼亚大学的Charles LeePowell结构实验室建造。在一九九九年四月完成后,测试将于五月开始。测试预计将于1999年7月完成,随后会有分析和报告。有关设计建议的报告预计于二零零零年八月完成。


CONCLUDING REMARKS

结论

The PRESSS Phase III test building and Design Recommendations will validate the seismic performance of five different ductile precast concrete systems. These systems are economical even using Force Based Design, but will be even more advantageous once their beneficial attributes can be directly taken into account using Direct Displacement Based Design (DBD).As is clear in the design of the test building, the benefits of the DBD approach to precast concrete buildings are substantial. Following validationof this design method by the PRESSSIII test building, a coordinated effortcan hasten the development of design recommendations. Once the design recommendations are published, the precast industry should be well positioned to implement the DBD approach and facilitate its acceptance into building codes.Recently, several codes have included sections on precast concrete seismic systems, but they apply primarily to emulative systems. These sections should be expanded to cover jointed systems and to incorporate the results of the PRESSS research program if its benefits are to be fully utilized. Then, precast concrete will truly be the “solution of choice” in all seismic regions of the world.

第三阶段的测试建筑和设计建议将验证五个不同的延性预制混凝土系统的抗震性能。即使使用基于力的设计,这些系统也很经济,但如果使用基于直接位移的设计(DBD)直接考虑它们的有利属性,这些系统将更加有利。在试验建筑的设计中,DBD方法对预制混凝土建筑的好处是显而易见的。在PRESSSIII测试大楼对这种设计方法进行验证之后,协调一致的努力可以加速设计建议的开发。一旦设计建议发布,预制行业应该很好地定位,以实施DBD方法,并促进其进入建筑规范的接受。最近,一些规范已经包括预制混凝土抗震系统的部分,但他们主要适用于模拟系统。这些部分应该扩大到连接系统,并纳入研究计划的结果,如果它的好处是充分利用。然后,预制混凝土将真正的解决方案的选择,在所有地震地区的世界。


ACKNOWLEDGMENTS

鸣谢

The PRESSS research program is funded by grants from the National Science Foundation, the Precast/Prestressed Concrete Institute, the Precast/Prestressed Concrete Manufacturers Association of California, Inc., and by various precasters and suppliers.Their contributions are gratefully acknowledged.In addition to the design and testing components of the PRESSS III project(NSF Grant Numbers CMS 97-10735(UW) and CMS 97-00125 (UCSD),analysis of the test structure is being performed by Lehigh University (NSFGrant Number CMS 97-08627). Their analysis is based on the methods developed in Refs. 13, 14 and 15.The technical input provided by many PCI members, especially by PCI’s Ad Hoc Committee on ATLSS and PRESSS under the chairmanship of Mario Bertolini, has played a significant role in the planning, development, and execution of this program.Also, M. J. Nigel Priestley, the principal coordinator of the PRESSS research program, played a key role inproviding leadership through all phases of this research.During the design of the test building, the following members of the PRESSS Phase III research team and Industry Advisory Group provided invaluable guidance and their contributions are greatly appreciated:

PRESSS研究项目由国家科学基金会、预制/预应力混凝土研究所、加州预制/预应力混凝土制造商协会以及各种预制机和供应商资助。感谢他们的贡献。除了PRESSS III项目的设计和测试部件(美国国家科学基金资助号CMS 97-10735(UW)和CMS 97-00125 (UCSD)),测试结构的分析由里海大学(美国国家科学基金资助号CMS 97-08627)进行。他们的分析基于参考文献13、14和15中发展的方法。许多PCI成员提供的技术投入,特别是马里奥·贝托里尼(Mario Bertolini)主席领导下的ATLSS PRESSS特设委员会,在该项目的规划、发展和执行中发挥了重要作用。此外,M. J. Nigel Priestley,PRESSS研究项目的主要协调员,在提供领导通过这一研究的所有阶段发挥了关键作用。在测试大楼的设计过程中,以下PRESSS三期研究团队和行业顾问组的成员提供了宝贵的指导和贡献,我们对此深表感谢


Industry Advisory Group

Mario J. Bertolini, ChairmanRobert ClarkNed M. ClelandThomas J. D’ArcyRobert E. EnglekirkS. K. GhoshPaul JohalRobert KonoskeH. S. LewRobert F. MastDoug MooradianJohn G. NannaDavid C. SeagrenEdward A. Wopschall

PRESSS Researchers

M. J. Nigel Priestley, Principal CoordinatorCatherine FrenchNeil M. HawkinsRebecca HixMichael E. KregerLe-Wu LuSuzanne D. NakakiStephen P. PessikiRichard SauseFrieder SeibleS. (Sri) Sritharan John F. Stanton


In addition, various producers and suppliers have donated significant products and effort to allow the five different systems to be tested. Theyare:

此外,各种各样的生产商和供应商捐赠了大量的产品和努力,以允许这五种不同的系统进行测试。他们:

A. T. Curd Structures, Inc.

Charles Pankow Builders, Ltd.

Clark Pacific Coreslab Structures, L.A.

Dywidag Systems International 

ERICO 

Fontana Steel

Headed Reinforcement Corporation

NMB Splice Sleeve

Pomeroy Corporation Spancrete of California

Sumiden Wire

Their support and donations are gratefully acknowledged.

感谢他们的支持和捐赠。(虽然论文里没有提及,但是我看到视频中有星联钢网,中国企业)


REFERENCES

参考文献

1. Priestley, M. J. N., “The PRESSS Program – Current Status and ProposedPlans for Phase III,” PCI JOURNAL,V. 41, No. 

2, March-April 1996, pp.22-40.2. Uniform Building Code, International Conference of Building Officials,Whittier, CA, 1997.

3. Building Seismic Safety Council,NEHRP Recommended Provisions forSeismic Regulations for New Buildingsand Other Structures, National Earthquake Hazard Reduction Program,Washington, D.C., 1997.

4. Priestley, M. J. N., “DisplacementBased Approaches to Rational LimitStates Design of New Structures,” Presented at the Eleventh European Conference on Earthquake Engineering,Paris, September 1998.

5. PCI Ad Hoc Committee on Precast Walls, “Design for Lateral Force Resistance with Precast Concrete ShearWalls,” PCI JOURNAL, V. 42, No. 5,September-October 1997, pp. 44-65.

6. Stanton, J. F., Stone, W. C., andCheok, G. S., “A Hybrid ReinforcedPrecast Frame for Seismic Regions,”PCI JOURNAL, V. 42, No. 2, MarchApril 1997, pp. 20-32.

7. Palmieri, L., Sagan, E., French, C.,and Kreger, M., “Ductile Connectionsfor Precast Concrete Frame Systems,”Paper No. SP162-13, Mete A. Sozen Symposium, ACI SP 162, American Concrete Institute, Farmington Hills,MI, 1997, pp. 313-355.

8. Stanton, J. F., MacRae, G., Sugata, M.,and Day, S., “Preliminary Test Reportof a Hybrid Frame Exterior Beam-Column Specimen Test,” University of Washington, Seattle, WA, March1999. 

9 . Palmieri, L., and French, C., “DuctileMoment-Resisting Connections forPrecast Frames in Seismic Regions:Experimental Study,” Manuscript submitted to PCI JOURNAL for publication .

10 . Palmieri, L., and French, C., “DuctileMoment-Resisting Connections forPrecast Frames in Seismic Regions:Numerical Simulation,” Manuscript submitted to PCI JOURNAL for publication .

11. Schultz, A. E., and Magana, R. A.,“Seismic Behavior of Connections inPrecast Concrete Walls,” Paper No.SP162-12, Mete A. Sozen Symposium, ACI SP 162, American Concrete Institute, Farmington Hills, MI, 1996,pp. 273-311.

12. Kurama, Y., Pessiki, S., Sause, R., andLu, L.-W., “Seismic Behavior and Design of Unbonded Post-Tensioned Precast Concrete Walls,” PCI JOURNAL,V. 44, No. 3, May-June 1999.

13. Perez, F., Pessiki, S., and Sause, R.,“Lateral Load Behavior and Design of Unbonded Post-Tensioned PrecastConcrete Walls with Ductile VerticalJoint Connectors,” ATLSS Report No.99-01, Center for Advanced Technology for Large Structural Systems,Lehigh University, Bethlehem, PA,January 1999.

14. El-Sheikh, M., Sause, R., Pessiki, S.,Lu, L.-W., and Kurama, Y., “Seismic Analysis, Behavior, and Design of Unbonded Post-Tensioned Precast Concrete Frames,” PRESSS Report No.98/04 (also Report No. EQ-97-02),Department of Civil and Environmental Engineering, Lehigh University,Bethlehem, PA, November 1997.

15. El-Sheikh, M., Sause, R., Pessiki, S.,and Lu, L.-W., “Seismic Behavior ofUnbonded Post-Tensioned PrecastConcrete Frames,” PCI JOURNAL, V.44, No. 3, May-June 1999.


补充视频:

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