Two-Way (Waffle) Flat Slab Design

The structural function of beamless floor system is to collect the gravity load and other load such as wind load etc. and to transfer to the vertical structural elements i.e. column through the combined capacity in flexure and shear. In Flat slab, the slab is directly supported on the columns. Moments and shear values are usually the largest over the columns. However, when spans are relatively small and imposed load is low, the thickness of slab can be increased to reduce the stresses at slab-column joint which would result in providing greater effective depth for negative moments occurring near the column. With increasing span and live load intensity, the thickness requirement increases which does not give economical solution. So, to tackle this problem flaring of the column at top is done such that the plan geometry at the column head is similar to that of the column. The column capital is intended primarily to increase the capacity of the slab to resist punching shear. The column capital stiffens the slab, which help in controlling the floor deflection. Thus, the floor span can be increased to some extent. Beyond a certain range of span, further stiffening of the slab is required which is achieved by increasing the slab thickness of the slab panel around the column capital. This portion of the slab is known as drop panel. For flat slabs and flat plates supported directly by columns, shear may be the critical factor in design. In almost all tests of such structures, failures have been due to shear or perhaps shear and torsion. These conditions are particularly serious around the exterior columns. In the present study, attempt has been made to understand different methods of analysis of flat slab and parameters, which governs the design parameters of the flat slab. Attempts have been made to study the provisions of flat slab in well-known international standards such as ACI 318, EC-2 and IS 456:2000. Keywords: Flat slab, drop panel, Column head, IS 456:2000, ACI 318, EC-2

Flat slab is reinforced concrete plate construction without beam. Without using beam, the obtainable profit is to minimize concrete volume, height/floor, and structural load. Other profits are simpler and economic reinforcement, scaffolding, and formwork. In this study, structural redesign of RSGM UGM Prof. Soedomo Yogyakarta building was made by using flat slab method. The objective of this study was to find structural dimension of floor and roof plates as well as reinforcement of the RSGM UGM Prof. Soedomo Building using structural system of flat slab, dimension of structural column and drop panel as well as reinforcement of the RSGM UGM Prof. Soedomo Building using structural system of flat slab. This method was to redesign using flat slab method complying with the standard of SNI 2847-2013 and software ETABS 2017. The results of analysis and calculation of structural dimension using flat slab method showed floor plate thickness of 170 mm; roof plate thickness, 120 mm; drop panel thickness, 270 mm with drop panel width of 2000 mm in direction x and 1500 mm in direction y, as well as use of column dimension of 500 mm x 500 mm. The analysis using software ETABS 2016 showed building structure in period (T) of 1.07 seconds.Keywords: RSGM UGM Prof. Soedomo Building, Drop Panel, Flat slab.

Structural systems that do not use a beam as the main component were first developed by Turner in 1906. This structural system is better known as a flat slab. The flat slab structure is supported by column heads and drop panels, or without drop panels, or without column heads. Several building codes such as IS 456: 2000, ACI 318-08, ACI 318-19, EC 2:2004, and NZS 3101 (Part 1):2006 provide guidance for designing flat slab systems under gravity loads only. However, many flat slab buildings are also built in areas with high earthquakes which can cause the collapse of buildings due to earthquake loads. In this paper the 10-level flat slab building structure design results are analyzed using nonlinear time history response analysis with the help of OpenSees Navigator software using several earthquake records, namely Kobe (Japan, 1995), Imperial Valley (California, 1979) and Tabas (Iran, 1978) which has been adjusted to the design spectra of the city of Yogyakarta. From the results of the analysis using OpenSees Navigator, it was found that the story drift that occurred was still within the limits required in the regulations, so that the building being reviewed was still within the limits of life safety design.

The structural design process is iterative and involves many design parameters. Thus, this paper presents a controlled framework for selecting the adequate structural floor system for reinforced concrete buildings and efficiently utilizing the corresponding construction materials. Optimization was performed using an evolutionary algorithm to minimize the total construction cost, considering the costs of concrete, steel reinforcement, formwork, and labor. In the problem formulation, the characteristic compressive strength of concrete was treated as a design variable because it affects the mechanical performance of concrete. The design variables included the column spacings, concrete dimensions, and steel reinforcement of different structural components. The constraints reflected the Egyptian code of practice provisions. Because the choice of the structural floor system affects the design details, three systems were considered: solid slabs, flat slabs with drop panels, and flat slabs without drop panels. Two benchmark examples were presented, and the optimal design results of the structural floor systems were compared. The solid slab system had the lowest construction cost among the three structural floor systems. Comparative diagrams were developed to investigate the distribution of construction costs of each floor system. The results revealed that an adequate choice of design variables could save up to 17% of the building’s total construction cost.

The Klandasan Parking Building (GPK) is an 8-story parking built in Balikpapan that serves as vehicle parking and uses a conventional structure system (columns, beams, plates) where the highest beam is about 800 mm. To maximize the clearance of each story, an alternative structure system is planned by removing beams called flat slabs. The new plan is conducted by modifying the structure into a dual system which consists of an Intermediate Moment Resisting Frame, a flat plate with drop panels used to withstand gravitational loads on buildings and a Structural Wall System (SWS) installed to resist lateral loads such as earthquake and wind. Structure’s plan refers to SNI 03-2847-2013 and SNI 03-1726-2012 which are Indonesia’s concrete and earthquake codes respectively. In addition, PPURG 1987 is also used to determine loads for the building. The analysis result shows that the building could be changed from 8 to 9 stories using the same total height of 8 stories. The depth of plates and drop panels which are supported by interior and exterior columns are 250 mm and 100 mm respectively. Turning to the shear wall, a thickness of 350 mm can be used to resist lateral loads.

The Animal Hospital Education of the Faculty of Veterinary Medicine (RSHP-FKH) at Udayana University is located on Sesetan Main Road, Markisa Alley, No. 6, South Denpasar District, Denpasar, Bali. The building structure is planned with a modified flat slab design incorporating drop panels around the column areas. The purpose of this modification is to provide flexibility in spatial arrangement, facilitate the installation of mechanical and electrical systems, and indirectly meet the height requirements specified by the local regulations in Bali. The structural analysis of the Animal Hospital Education building at RSHP-FKH, Udayana University was conducted using the ETABS v.18 software, following the guidelines of the Indonesian National Standard (SNI). The analysis focused on the effect of drop panels on shear slip in the flat slab. The analysis aimed to determine the magnitude of deflection and its corresponding locations in the structure. The results of the analysis provide relevant information regarding the strength and stability of the building structure, ensuring that the RSHP-FKH building at Udayana University meets the established standards.

Analysis and design of buildings must take earthquakes into account. Analyzing how a structure will react to a given set of loads is called structural analysis. Design is the process of determining the structure's proper parameters. It would take a long time to do structural analysis and design by hand. Any building may be easily analysed and designed with the help of software. The goal of this research and design study is to compare and contrast four common commercial building slab configurations—the conventional slab, the flat slab with drop panels, the grid/waffle slab, and the structure with a load bearing wall. At get to the results, a study was run in STAAD to analyse the impact of varying pressures on two different slab designs. The cutting edge of computer programming. The IS-1893:2002 standard mandates the incorporation of seismic forces. We used IS-456:2000 to determine how wide, tall, and deep to make the beams, columns, and slabs. IS-875:1987 (Parts 1 and 2) specifies the requirements for applying load combinations, dead loads, and imposed loads (Parts 3 and 5). (Part 5). Wind speeds of 55 metres per second and an earthquake zone of 5 will be employed as criteria in the next research. The results of a research comparing the displacements, moments, shear forces, and axial forces in two different slab pattern structures are shown using bar charts. Data is presented in the form of tables and bar charts. In general, the greater the number of stories, the greater the amount of movement between floors. Buildings using grid slabs performed better in the examination of the building's resistance to wind and seismic loads, and they were also shown to be more cost-effective.

This paper investigates the effects of concrete grades and column spacings on the optimal design of reinforced concrete (RC) buildings. To this end, cost design optimization was performed for buildings with three different floor systems: flat plates (FS), flat slabs with drop panels (FSDP), and solid slabs (SS). The evolutionary method provided by the Excel solver was used as the optimization algorithm because it can deal with the complex nature of structural design problems. The objective function was the total construction cost of the building, including the costs of concrete, reinforcement bars, labor, and formwork, while still fulfilling the constraints of the Egyptian code of practice (ECP-18). The applicability of the presented algorithm was investigated in a design example, where the tuning of the evolutionary algorithm control parameters was sought, and the best parameters were investigated. Two case studies were employed to study the impacts of changing the column spacing and concrete grades on the optimal cost for each floor system. The results showed that low concrete grades, (i.e., characteristic strength up to 40 MPa) and column spacings up to 5 m are preferred in terms of direct construction costs for low-rise RC residential buildings.

Effect of Embedded Pipelines within Slab Thickness on Punching Shear Capacity of Flat Slabs

The effective beam width model (EBWM) has been used for estimating force and drift demands on flat plate frames under lateral loads. The accuracy of this model depends strongly on how to estimate the effective stiffness of flat plate slabs. With an increase in slab moments due to lateral loads, slab cracks occur and propagate on the slab, which leads to a reduction in slab flexural stiffness. For post-tensioned (PT) flat plate slabs, the initiation and propagation of slab cracks can be delayed due to slab in-plane compressive stress induced by PT tendon forces. This study investigates the contribution of slab in-plane compressive stress to the slab stiffness reduction factor, which is defined as the ratio of slab stiffness obtained from a cracked slab section to that from the corresponding uncracked slab section. For this purpose, this study collected the test results of PT flat plate slab–column connection specimens and estimated the slab stiffness reduction factors (β) for those specimens with respect to a level of applied slab moment. Non-linear regression analysis is used to propose an empirical equation computing β for PT flat plate slabs using β estimated from the test results. The accuracy of the empirical equation for β is verified by comparing the lateral stiffness of a two-storey PT flat plate frame, obtained using the EBWM with the empirical equations for β, with that estimated from shaking table test results on the frame.

Over the past few years, punching shear has been in the forefront of both research teams and professional public due to a new approach to its verification according to Model Code 2010. From this topic, the task of flat slabs strengthening against punching shear has arisen. This problem, and in particular the problem of flat slabs strengthened by additional concrete column heads, is the focus of this paper. Structures are analysed using a 3D FEM models including material and geometric nonlinearity. The way of modelling is validated against experiments on non-strengthened flat slabs subjected to punching shear. At first, strengthening with a rigid connection at the interface between structures is considered and then, several different types of connection at the interface are evaluated. Finally, strengthening of structures with varying lengths of top flexural reinforcement in the slab is modelled while minimum anchorage length outside the additional column head is verified.

A new engineering practice in modern buildings is to use beams with web openings to allow the passage of services within the depth of the beam instead of underneath the beam. As the web post failure may occur before the section reaches the limiting temperature, usually an increase in the fire protection may be required for members with web openings in comparison to its equivalent solid section. The aim of this work is to present an experimental study of unloaded solid and cellular beams with circular holes in fire conditions with and without intumescent fire protection. These preliminary tests results are the basis for generating an elemental multi-temperature analysis needed to assess cellular beams with intumescent protection and give experimental results for calibration of further numerical simulations. The experimental results show that, considering the same nominal fire protection thickness, one can obtain a higher fire resistance time for solid beams when compared with cellular beams. The tests performed, with different hole diameters and web-post widths, points that to achieve the same fire resistance time, a cellular beam will need a higher fire protection compared to an equivalent solid beam. Also, a special care is needed when the intumescent coating is applied around the hole to avoid the intumescent contraction, applying for example an over coating.

THE paper suggests a new approach to the calculation of the bending strength of semi‐monocoque (and possibly fully mono‐coque) aircraft fuselage shells. The method described uses directly load‐deflexion graphs obtained from laboratory compression tests on panels representative of the shell at the section under consideration, and is analogous to the calculation of the form factor for a solid beam section, which factor is dependent on the shape of the section and on the stress‐strain relationship of the material of which the beam is made.

<p>This scientific paper describes a bionic optimization of flat slabs. Emphasis is placed on the load bearing capacity, but sustainability and efficiency aspects are also considered. Previous investigations show that slabs enhanced by nature can lead to considerable material saving without loss of bearing capacity. This paper presents the results of extensive test work to optimize the punching shear resistance of flat slabs inspired by natural systems. In this case the reinforcement is positioned stress-oriented, so that a spider web-like reinforcement arrangement is created. The results of the numerical simulations show that in comparison to orthogonally reinforced slabs an increased load capacity with a smaller reinforcement ratio can be achieved.</p>

A construction sequence tends to influence the short‐term and long‐term behaviours of flat plate and flat slab systems, especially as it relates to serviceability conditions and, in some occasion, to strength‐related issues. Present material technologies, especially as it relates to high‐performance concrete (HPC), may have positive influence on the construction sequence and planning of these systems. Proper precautions in construction practice nowadays is required as it may influence the behaviour positively and improve the serviceability behaviour, especially as it relates to cracking and stiffness control because of the use of HPC.The purpose of this paper was to study the behaviour of flat plate/slab system behaviour when utilizing HPC during construction and their impact on the long‐term performance of these systems. Through this study, several construction sequence analyses were performed by considering the effect of slab strength and stiffness development during construction cycle, shoring member stiffness and the cracking effects on the long‐ and short‐term behaviours. Also, it was performed to study different shoring methods of a high‐rise building system with a flat plate floor system as it may influence a typical floor construction cycle and overall construction schedule in a high‐rise building. Copyright © 2008 John Wiley & Sons, Ltd.