There is currently Insufficient knowledge to determine whether the rigid diaphragm assumption will lead to adequate design for a given structure, These, in turn, can be used to determine the mode shapes of the system and the participation factors for earthquake response. The slab with a hole is modelled either accurately as a diaphragm using finite elements, either approximately using the appropriate assumptions, e.g. This paper presents a design procedure covering the diaphragm action of a hybrid floor slab comprising of Dramix steel fibre reinforced concrete (SFRC) topping on profiled metal sheeting. Copyright © 2012 John Wiley & Sons, Ltd. In-plane floor deformability is an important issue for the correct assessment of the behaviour of Reinforced Concrete (RC) structures subjected to seismic loads. The in-plane flexibility of floor-slab systems has been observed to influence the seismic response of many types of reinforced concrete buildings. solver model under consideration ; Diaphragm option slab item property A case study has been conducted on low rise, medium rise, and high rise buildings. Northridge Earthquake Buildings Case Studies Project, Seismic Safety Commission, State of California, Proposition 122: Product 3.2, Sacramento, Calif. Corley, W. G.; Cluff, L.; Hilmy, S.; Holmes, W.; and Wight, J., 1996, Damage Analysis of Reinforced Concrete Frame Shear-Wall Structures," slabs act as rigid diaphragms. However, for structures in which the stiffness of the vertical system and the stiffness of the slab system do not differ greatly, diaphragm deformation of the floors must be explicitly considered in analysis. retrofit measures recommended included discriminate use of internal reinforced concrete skin walls, providing a rigid diaphragm behaviour mechanism in existing slabs, introducing stainless steel reinforcement bands in the existing masonry walls, cross-pinning and end-pinning in walls and pillars, and strengthening of arches and elevation features. The models used for slab–column frames and shear walls were verified by comparing with other available models or laboratory tests. 641-650. In systems that contain beams or ribs – like in wide-module, two-way joist and grillage systems – the elements below the slab help stiffen the diaphragm even further. In current practice, horizontal diaphragms are typically assumed to be rigid, thus neglecting the effect of their in-plane movement relative to the vertical LFRS. Figure 5. The procedure was applied to low-rise reinforced concrete buildings damaged in recent earthquakes in Japan including the 1995 Hyogo-Ken-Nambu (Kobe) Earthquake and its validity was discussed. Three-story and five-story RC buildings with end shear walls and two aspect ratios (approximately 2:1 and 3:1) were developed and designed according to current code procedures assuming rigid diaphragm behavior. A more straightforward analysis is possible when assumptions are made concerning the rigidity of a diaphragm. Tex., 176 pp. To illustrate the method, a two-storey structure, the Arvin (California) High School Administration Building, damaged in the Kern County earthquake of 1952, has been analysed in its transverse direction. The purpose of this study is to establish the effects of rigid floor assumption on shear forces that occurs on shear walls of building type structural systems. The derived response reduction factors will be useful for the design of reinforced HCBM wall panels subjected to lateral forces generated due to earthquakes. Hi @Nissar19. Where the width of the collectors is equal to the thickness of the wall, all the tension and compression forces from the collector are transferred directly into the boundary of the wall, and Avf is determined using the above equation based on the uniform shear along the length of the wall (which is equal to RA/L2). The study addresses the earthquake study due to performance of critical frame reinforced concrete building which were subjected to low-intensity earthquakes effects. Resistance of Structures with Concrete Diaphragms," master's thesis, As noted previously, one of the primary roles of a diaphragm is to transfer wind forces to the elements of the LFRS. The resultant wind force acts through the geometric center of the building at that level. Type of Roof System : Roof â¦ Chord reinforcement must also be located around large openings and must be properly developed within the slab. As a result, the high-rise building developed plastic hinge due to the earthquake intensity of 0.05 g and have damage indexes in the range 0.050 (light damage level) to 1.0 (collapse). This assumption distributes lateral loads between the resistant elements according to their rigidities, and decreases the degree of freedom that creates easier analysis. It is closely related to that part of the strong motion which contributes significantly to the seismic energy as recorded at a point and to the related spectral amplitudes. The dowel reinforcement must be fully developed for tension into the wall and the diaphragm (see Section 1-1 in Figure 4). Hi, i am currently modelling a precast concrete wall frame. 137-142. Moreover, if the floor slab panels experience cracking or yielding due to pronounced in-plane distortions, the seismic response of the entire building system may be significantly altered. It was found that the use of a flexible diaphragm model had the largest impact on the three-story, 3:1 aspect ratio building and that the various analysis procedures in FEMA 273 gave differing assessments of the adequacy of this case study building. Unit shear forces, net shear forces, and collector forces in a diaphragm. The performance of critical frame reinforced concrete building when subjected to earthquake motion (Near source: Acheh) was addressed. However, this observation cannot be generalized, because other design practices may favor the presence of semi-rigid, semi-flexible or flexible diaphragms, particularly for floor spans of 10 meters or more, frequently used in office buildings. According to the American Concrete Institute’s ACI 318, Section 12.3, diaphragms must have sufficient thickness so that all applicable strength and serviceability requirements are satisfied. Engineers should concern about and consider the loading for reinforced concrete building due to earthquake in Malaysia’s building design procedure. The diaphragm condition was assessed using the following parameters: (a) profiles of lateral displacements (Δ) obtained in the top level of the studied floor systems normalized with respect to the lateral displacements at the same level for a rigid diaphragm model (Δrigid) and, (b) the amplification factor for the base shear of central frames with respect to perimeter frames. Structure," 1994 Northridge Earthquake Buildings Case Studies Project, Selection and/or peer-review under responsibility of Universiti Teknologi MARA Perak and Institution of Surveyors Malaysia (ISM). Barron, ... Three and five-story RC buildings with end shear walls and two aspect ratios were developed and designed according to current code procedures assuming rigid diaphragm behavior. It is shown that displacements of single storey elastically responding structures tend to be most significantly affected by diaphragm flexibility. To read the full-text of this research, you can request a copy directly from the authors. Structural Dynamics, V. 13, No. Earthquake Simulation Study of a One-Sixth Scale-Model RC Building with Flexible Floor Diaphragms. Building of Ampang Jaya Municipal Council (MPAJ), Employees’ Provident Fund (KWSP), Block F (Public Work Department, JKR), and Department of Survey and Mapping Malaysia (JUPEM) were chosen as main models for this study. Seismic Safety Council, Washington, D.C. The design and detailing of diaphragms that are cast-in-place concrete slabs utilizing non prestressed, steel reinforcement in building structures are covered in this publication. This paper presents an simplified macromodeling scheme to incorporate the effect of inelastic floor flexibility in the seismic response analysis of RC buildings. It was observed that the residual seismic capacity of a damaged RC building structure can be evaluated conservatively according to the R index employed in the Guideline, and from a practical point of view, the R index is an effective way to identify the safety of damaged structures against aftershocks. Two variables that favor the potential flexibility of the diaphragm were assessed in the research: a) the plan aspect ratio of buildings and, b) the stiffness of the floor system. In addition to supporting gravity loads, floor and roof systems in typical reinforced concrete buildings act as diaphragms which transfer the lateral forces to shear walls, frames, or other elements that make up the lateral force resisting system (LFRS). Reinforced concrete slabs, at least those designed to span in one direction, are no different conceptually from any other beams, with the following three caveats.First, only 3/4-in. Design of Reinforced Concrete Diaphragms for Wind. This study includes, compressive strength of unit block, ungrouted and grouted HCB prisms, flexural strength evaluation, testing of HCBM panels with and without opening. ignoring the diaphragmatic behaviour. This paper presents a new analytical method for the dynamic analysis of some one- and two-storey buildings whose floors may have significant in-plane flexibility. 735-742. ... diaphragm, chord and collector design in accordance with the 2012 IBC. Rigid vs. Semi-rigid diaphragm by CSI ETABS Ghaith Al-Hourani Rigid vs. Semi-rigid diaphragm Rigid diaphragms have infinite in-plane stiffness properties, and therefore they neither exhibit membrane deformation nor report the associated forces, whereas semi-rigid diaphragms simulate actual in-plane stiffness properties and behavior. V. V, pp. Diaphragms may be constructed of structural materials, such as concrete, wood, or metal in various forms. The members of the LFRS will be subjected to direct shear forces plus shear forces due to the torsional moment generated by the eccentricity. The study shows that the in-plane deflections of floor slabs impose a larger demand on strength and ductility of flexible frames than predicted values using the assumption of rigid or elastic slabs. The paper presents an evaluation of medium-rise reinforced concrete building in Peninsular Malaysia which is subjected to low intensity earthquake effects. V. 11, Northridge Earthquake of January 17, 1994 Reconnaissance Report, Results of the analysis are presented comparatively. In particular, the study of the seismic behaviour of existing RC buildings is strictly related to the initial assumptions made by practitioners on the numerical model, which usually assume the floor as rigid, according to a criterion of reducing time and computational efforts. Previously proposed force and displacement criteria were used to assess their behavior as diaphragm. The following equation can be used to determine the required area of the dowel bars Avf for shear transfer: For hardened concrete that is clean, free of laitance, and not intentionally roughened, μ = 0.6 for normalweight concrete in the typical case where the slab and wall are cast at different times. CRSI (Concrete Reinforcing Steel Institute). A three-dimensional analysis that considers the relative rigidities of the diaphragm and the elements of the LFRS provides the most accurate distribution of the forces in these components. This paper presents a design procedure covering the diaphragm action of a hybrid floor slab comprising of Dramix steel fibre reinforced concrete (SFRC) topping on profiled metal sheeting. The buildings analyzed, which were subjected to the Acheh earthquake ground motion, developed plastic hinge due to the earthquake intensity of 0.012 g for all buildings except building of Employees’ Provident Fund (KWSP) which developed plastic hinge due to the earthquake intensity of 0.05 g and had damage indexes in the range 0.00 (no damage) to 1.0 (collapse). ACI 318-14, Farmington Hills, Michigan. Seismic Safety Commission, State of California, Proposition 122: Product 3.2, The building performed the early yielding point at 3.22 sec for beam element at the intensity of 0.01g. Hills, Mich., pp. the Seismic Rehabilitation of Buildings," FEMA Publication 273, Building CRSI (Concrete Reinforcing Steel Institute). Figure 4. Displacement ductility factors and response reduction factors have been evaluated based on experimental results. Applied Technology Council (ATC), 1997a, "NEHRP Guidelines for But as it turns out, only the slab with span-to-depth (depth is length of slab in direction of lateral loads) ratio of less than 3 and without horizontal irregularity can be treated as rigid diaphragm. The SFRC alternative is shown to be an efficient and structurally adequate equivalent to â¦ At the mass center of each rigid floor, there is a master node having three degrees of freedom to represent the two in-plane translations and one out of plane rotation. reinforced concrete building incorporating a shear wall core and a perimeter moment frame was developed, incorporating a truss at each floor level to represent the floor diaphragm, as per the Truss Method developed by the author (Scarry, 2014a, 2014b). Scale models of a portion of the floor system were tested to examine in-plane behavior. With this aim, a six-story building typical of the Eixample-Barcelona district was used as a case study. From the study, it is observed that fully grouted and partially reinforced HCBM panel without opening performed well compared to other types of wall panels in lateral load resistance and displacement ductility. 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