REDESIGN BUILDING STRUCTURE RSGM UGM PROF. SOEDOMO USING FLAT SLAB METHOD WITH DROP PANELS

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 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

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.

In the present scenario with the booming of construction industries, the study on the various structural behavior of structural components is an important criterion that has to be taken into considerations during the analysis and design process. Flat slabs are the vertical load resisting members that has various advantages compared to the conventional slab system. It reduces the storey heights and hence conservatively increase the total number of floors. In comparison to conventional slab 70% of the cost saving is done in case of Flat slabs and 50% cost saving in case of formwork. Due to the controversy that the flat slab system is least resistant to seismic forces, there is a need to study flat slab with bracing and flat slab without bracing. The analysis was carried out using Abaqus software for both static and dynamic cases. The structure is modeled for linear static and non-linear dynamic analysis under prestressing forces. The analysis was carried out manually using Load balancing principle and Equivalent frame method. The structure was modelled and analyzed using Abaqus software. The analysis results stated that, though the stresses and the displacement in the flat slab with braces are reduced considerably than that for flat slab without braces, the stresses and displacement produced are within the limits for the loading considered. Hence, in this case considered for warehouse building and for the considered loading conditions the stresses and displacement are within the limits for both cases. The stresses and displacement are within the limits and safe against lateral forces. The overall preference in the flat slab element leads to optimum design.KeywordsPrestressed flat slabIn-plane behaviorSingle-storey frameStatic analysisDynamic analysisValidation

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.

3D finite element investigation of the compressive membrane action effect in reinforced concrete flat slabs

In an attempt to characterize the membrane-associated Ca2+-ATPase activity in the roof and floor plates of the developing rat spinal cord (36), the effect of quercetin, a potent inhibitor of Ca2+-transporting ATPase was histochemically examined. Histochemical localization of ADPase and AMPase actvity was also investigated in relation to possible involvement in the enzymatic hydrolysis of ATP.When tissue specimens were incubated in media containing quercetin at a concentration of 0.1 or 0.5mM, the Ca2+-ATPase activity in both roof and floor plates appeared to be diminished, in a concentration-dependent manner, as seen under light microscopy. The inhibitory effect of quercetin was clearly evident in the floor plate. ADPase activity was also noted in both the roof and floor plates, particularly in the roof plate. Electron microscopic study revealed that the ADPase activity was mainly localized in the lateral and luminal plasma membranes of these plate-forming cells, resembli g the cytochemical localization of Ca2+-ATPase activity. There was, howover, no evidence of histochemical activity of AMPase in the developing spinal cord. These findings indicate that, in addition to activity of Ca2+-transporting ATPase, the roof and floor plate-forming cells during embryonic development may possess ecto-nucleotidases which hydrolyse ATP to AMP.

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.

A “waffle” flat slab is a two-way joist system. Under the general provisions of the 1995 Code, Chapter 13, the two-way joist portion may be combined with a solid column head or with solid wide beam sections on the column centerlines for uniform depth construction. These are the usual applications, favored for economy of formwork and the unobstructed level ceiling with a regular pattern of void spaces utilizable for lighting or ventilating fixtures. The arrangement of two-way joists with a solid head results in a slab stiffness distribution similar to that for a solid slab with a drop panel. The use of solid “beam” sections on the column centerlines also provides a solid full depth for shear transfer to the columns and permits concentration of moment reinforcement at the column. Other common variations are cantilevered edges or use of spandrel beams deeper than the uniform depth elsewhere.

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.

East Asia is characterized by an east-west topographic dichotomy on the two sides of the North-South Gravity Lineament (NSGL), a feature not associated with major basement boundaries. The NSGL also marks an abrupt change in the thickness of the continental crust and the lithospheric mantle, as well as that in the associated residual topography. Both the mechanism and timing for the formation of this unique East Asian lithospheric property remain unclear. We reviewed the key tectonic records of East Asia since the early Mesozoic, with a particular focus on the plausible underlying mantle dynamics. The observation that widespread Jurassic-Early Cretaceous crustal extension occurred on both sides of the NSGL and that Cenozoic rift basins were predominantly to the east of the NSGL suggests that the seismically observed East Asian lithospheric structure came into being no earlier than the Cretaceous. Several flat-slab models have been proposed. We suggest that a combination of these models could explain the unique East Asian lithospheric evolution since the Middle Mesozoic. Further ground truth using quantitative geodynamic models with data assimilation demonstrates that a flat slab could significantly reduce the thickness of the overriding plate by dislocating and entraining the lower mantle lithosphere. Meanwhile, an advancing flat slab causes widespread upper-lithosphere compression and disappearance of the mantle wedge, implying regional-scale surface uplift (or reduced subsidence) and magmatic quiescence, respectively. We identify two episodes of Mesozoic flat slabs below East Asia, one during the Jurassic-Early Cretaceous and the other during the Late Cretaceous. The former affected the eastern half of North China and Northeast China, and the latter affected the entire region east of the NSGL from Northeast China to South China. These two flat-slab cycles largely determined the evolution of the lithosphere and topography within East Asia since the Mesozoic.

Due to the demand for slender and functional buildings, flat slabs are a frequently used load‐bearing element in buildings. However, the concentrated load introduction at the slab‐column connection is often the governing detail in design due to punching shear failure. Therefore, the punching shear behavior of flat slabs has been intensively studied in the past, mostly on flat slab cutouts, as the testing of flat slab systems is expensive. The investigated main characteristics of the punching shear behavior were hereby investigated and form the basis for today's design equations. However, new investigations on flat slab systems demonstrate clearly favorable influences of the system load‐bearing effect – namely compressive membrane action and moment redistributions. These phenomena lead to significant load reserves in continuous slabs and remain unconsidered in tests on flat slab cutouts. Since the design approaches are based on the available test data on cutouts, the system influences occurring in engineering practice stay disregarded. To fill the gap in experimental data deriving more advanced design approaches, a novel test setup was developed for the efficient investigation of system behavior using isolated flat slab specimens with externally applied load‐dependent loading conditions. The test program consisted of two test series with a total of 10 test specimens. The test results reveal up to 48% increased punching shear resistances going along with reduced deformations compared to isolated flat slab cutouts.

SUMMARY Flat slab subduction has been ascribed to a variety of causes, including subduction of buoyant ridges/plateaus and forced trench retreat. The former, however, has irregular spatial correlations with flat slabs, while the latter has required external forcing in geodynamic subduction models, which might be insufficient or absent in nature. In this paper, we present buoyancy-driven numerical geodynamic models and aim to investigate flat slab subduction in the absence of external forcing as well as test the influence of overriding plate strength, subducting plate thickness, inclusion/exclusion of an oceanic plateau and lower mantle viscosity on flat slab formation and its evolution. Flat slab subduction is reproduced during normal oceanic subduction in the absence of ridge/plateau subduction and without externally forced plate motion. Subduction of a plateau-like feature, in this buoyancy-driven setting, enhances slab steepening. In models that produce flat slab subduction, it only commences after a prolonged period of slab dip angle reduction during lower mantle slab penetration. The flat slab is supported by mantle wedge suction, vertical compressive stresses at the base of the slab and upper mantle slab buckling stresses. Our models demonstrate three modes of flat slab subduction, namely short-lived (transient) flat slab subduction, long-lived flat slab subduction and periodic flat slab subduction, which occur for different model parameter combinations. Most models demonstrate slab folding at the 660 km discontinuity, which produces periodic changes in the upper mantle slab dip angle. With relatively high overriding plate strength or large subducting plate thickness, such folding results in periodic changes in the dip angle of the flat slab segment, which can lead to periodic flat slab subduction, providing a potential explanation for periodic arc migration. Flat slab subduction ends due to the local overriding plate shortening and thickening it produces, which forces mantle wedge opening and a reduction in mantle wedge suction. As overriding plate strength controls the shortening rate, it has a strong control on the duration of flat slab subduction, which increases with increasing strength. For the weakest overriding plate, flat slab subduction is short-lived and lasts only 6 Myr, while for the strongest overriding plate flat slab subduction is long-lived and exceeds 75 Myr. Progressive overriding plate shortening during flat slab subduction might explain why flat slab subduction terminated in the Eocene in western North America and in the Jurassic in South China.

The economic design of the slabs is the most influential on the construction cost and choosing the appropriate system is the key to the slabs optimal design, and there are many systems that have been developed recently to reach the most economical design. In this research, we try to mix two systems, each of them has its optimal use, and each of them has its advantages and limits for uses, and they have been mixed to try to find a dual system with more advantages. This paper presents a slab system consisting of flat slab system that its field strip areas were replaced with two-way hollow block systems. Consequently, the total weight of the resulting slab was reduced, which positively affected the quantities of steel reinforcement used directly, in addition to its reflection on the design of columns and foundations due to the low self-weight of the slabs. The validity of the proposed concept has been verified through a finite element analysis using Program SAP2000 that was applied to several cases with different configurations under static and dynamic loadings.