Comparative Analysis for Building with Flat Plate Slabs and Void Slab using U-Boot Technology

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.

Numerical Analysis of Voided Flat Slab

Finite element analysis of concrete filled tube column to flat plate slab joint

Indonesia is located in a seismically active region due to the presence of the Eurasian Plate and the Indo-Australian Plate. This means that buildings and non-building structures must be designed to withstand seismic forces. One of the critical elements in resisting earthquakes in a building is the floor slab. In addition to resisting seismic forces, the floor slab also serves as a walking and activity area for people. There are several types of floor slab construction, for example flat slab and two-way slab. When considering which type of floor slab construction to use in a building, a seismic performance analysis of the slabs is necessary to evaluate their effectiveness under gravitational loads and lateral forces. This study examines seismic performance indicators such as base shear, story shear, story displacement, and story drift that occur in each type of floor slab. The dimensions and specifications of the slabs used will be adjusted according to minimal requirements. The seismic analysis is conducted in three dimensions using response spectrum analysis. Based on the analysis results, it can be concluded that two-way slabs exhibit higher seismic resistance compared to flat slabs, as they result in greater base shear, story shear, story displacement, and story drift. Consequently, the design of buildings with two-way slabs will be safer against larger seismic loads than those with flat slabs. Abstrak Indonesia berada pada daerah rawan bencana gempa karena dilewati oleh lempeng Eurasia dan lempeng Indo-Australia. Hal ini berarti bangunan gedung maupun non gedung hraus dirancang menahan gaya gempa. Salah satu elemen yang membantu menyalurkan beban lateral gempa adalah pelat lantai. Selain itu, pelat lantai juga berfungsi sebagai tempat berpijak dan beraktivitas bagi manusia. Terdapat beberapa jenis konstruksi pelat lantai, contohnya adalah flat slab dan two-way slab. Dalam mempertimbangkan jenis konstruksi pelat lantai yang akan digunakan pada bangunan, dibutuhkan analisis kinerja seismik dari pelat yang dapat bekerja dan seberapa optimal mereka saat dibebani gravitasi dan gaya lateral. Penelitian ini mengkaji kinerja seismik seperti base shear, story shear, story displacement, dan story drift yang terjadi pada masing-masing jenis pelat lantai. Dimensi dan spesifikasi pelat yang digunakan akan disesuaikan dengan kebutuhan minimal. Analisis gempa dilakukan secara tiga dimensi menggunakan analisis respons spektrum. Berdasarkan hasil analisis dapat disimpulkan bahwa two-way slab memiliki ketahanan seismik yang lebih tinggi dibandingkan dengan flat slab karena menghasilkan base shear, story shear, story displacement, dan story drift yang lebih besar. Hal ini mengakibatkan desain dari bangunan konstruksi two-way slab akan lebih aman terhadap beban gempa yang lebih besar dibandingkan dengan flat slab.

Plenty of waste plastic is one of the major problems for environmental sustainability as plastic contaminates the mainland, rivers, and seas. Moreover, many-sided behavior of waste plastic (lightweight, flexible, cheap, strong, and moisture-resistant) can make it a replacement for or alternative to coarse aggregate in concrete. This paper investigates the properties and strength of reinforced concrete flat plate slabs using recycled waste plastic as a coarse aggregate instead of the conventional aggregate to produce lightweight concrete. Also studying the effectiveness of adding polypropylene fibers for enhancing both concrete properties and shear strength of the reinforced concrete respectively in a flat slab. All specimens had the same dimensions and main flexural reinforcement ratio and they were subjected to concentrated vertical loads. Four mixes had been tested in this work, the results showed that using waste plastic mixed with polypropylene fibers to produce lightweight concrete was very promising. It was observed that by adding polypropylene fibers the failure pattern was shifted from punching to flexural. Ultimate load, crack pattern, and deflection had been included and discussed for all specimens.

Progressive collapse, where a localized member failure causes widespread structural collapse, has become a critical concern nowadays, due to its potential to cause significant financial losses and loss of human life. Triggers include natural disasters like earthquakes and floods, as well as accidents, attacks and explosions. Reinforced concrete flat slab structures, which are eminent for their architectural flexibility and have larger spans, are particularly susceptible to disproportionate collapse, due to the lack of floor beams, which can redistribute loads after a column failure, unlike moment frame buildings. This research examines how multi-story reinforced concrete flat slab buildings behave, under prescribed gravity load combinations, compared to conventional framed buildings. The effects of removing columns at specified locations from an intermediate floor of the multistorey building are also examined. However, this investigation covers both the column removal approaches to check a possibility of disproportionate collapse which are; static removal and dynamic instantaneous removal. Furthermore, the research also assesses the efficacy of perimeter beams, in minimising the risk of gradual collapse in flat slab structures, by scrutinising their ability to reduce joint displacement, chord rotation, and demand capacity ratio. ETABS v18 was used to analyze all the 18 models. The findings revealed that buildings are more prone to progressive collapse when corner columns are removed, as opposed to edge and interior columns, due to higher Demand-Capacity Ratios (DCR) and joint displacement. In comparison to dynamic analysis, the static evaluation exhibited greater DCR values and vertical joint displacement. Furthermore, since they have a more efficient load redistribution mechanism, traditional framed structures performed better than flat slab models. The simulations additionally indicated that, adding edge perimeter beams, substantially lowered the possibility of progressive collapse in flat slab structures. Moreover, the tested flat slab building models, with and without perimeter beams showed no indications of progressive collapse, when specified columns were removed from the intermediate floors, since the DCR values of the crucial columns stayed within the permissible range of 2.0. In conclusion, structures built in compliance with IS 1893:2016 code and designed to withstand seismic loads demonstrate stronger resistance against significant damage, brought about by column failures.

Voided slab systems were developed using segmented void formers such as spherical or oval plastic balls for two-way slab applications. This type of slab is expected to behave like a general two-way reinforced concrete slab because it has segmented voids, rather than the continuous voids of hollow core slabs. However, the structural behaviors of two-way voided slabs with segmented voids have not been clearly verified. Therefore, this paper analyzes the possibility of applying a donut-type two-way voided slab, which was investigated with a 12-point two-way bending test focused on global behaviors, including its load bearing capacity, flexural stiffness, ductility, deflection, and load distribution. In addition, the design method of a donut-type two-way voided slab was reviewed through the yield line method. The test results showed that one donut-type two-way voided slab acted like a conventional two-way reinforced concrete slab with the load distributed evenly between the different directions; however, another donut-type two-way voided slab with different characteristics showed uneven load distribution with different crack patterns. In addition, the yield line method could predict the load bearing capacities of the donut-type voided slabs with approximately 95% accuracy.

With the growing need for multistory buildings in a variety of industries, the need for novel structural solutions has become critical. This research looks at the structural behaviour of wide span structures, with an emphasis on the use of various slab forms to meet the problems provided by growing architectural trends. The study undertakes a detailed literature analysis, looking into the use of Grid Slabs, Flat Slabs, Waffle Slabs, and Ribbed Slabs alongside regular slabs to improve stiffness and load-carrying capability in large-span buildings. Architects are challenged to accommodate bigger spans while minimising the number of columns, which has led to the introduction of novel slab layouts. Grid Slabs, which have unique grid patterns, and well-established Flat Slabs are popular alternatives. The analysis of the literature reveals an increasing trend among academics who have effectively used various slab designs to meet the issues given by long spans. The findings provide architects, structural engineers, and construction industry stakeholders significant insights into the performance features and advantages associated with each slab type. This study adds to the continuing discussion about optimising structural designs for large-span structures to meet the changing demands of current construction practises. The complete analysis is a helpful resource for professionals involved in multistory building design and construction, assisting in informed decision-making and supporting developments in the field.

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.

Parking garages are among the concrete structures that suffer from corrosion and deterioration due to exposure to deicing salts. The 40-year-old La Chanceliere parking garage in Quebec (Canada) showed severe corrosion-related deterioration and was in need of costly rehabilitation. As its structural system consisted of two-way flat slabs and the steel reinforcement was severely corroded in most of the slabs, the City of Quebec (structure’s owner) decided to replace the structure’s flat slabs (a total area of about 3,160 m2) with new ones, while maintaining the main supporting elements (columns and retaining walls). The consulting firm produced two designs with steel reinforcing bars and glass-fiber-reinforced polymer (GFRP) reinforcing bars. Based on the comparative cost analysis of the steel-reinforced and GFRP-reinforced designs, the city opted for GFRP bars. The flat-slab system was designed according to CAN/CSA S806-12 with GFRP bars as main reinforcement, the world’s first application of its ...

Analysis of Mechanical Characteristics of Steel-Concrete Composite Flat Link Slab on Simply-Supported Beam Bridge

Post-tensioning has become a strong contender for manufacturing reinforced concrete (RC) members, especially for flat slabs in large-span structures. Post-tensioned (PT) slabs can lead to considerable material savings while reducing the embodied carbon (embodied CO2), construction time, and life cycle maintenance and repair costs. In this research, a novel hybrid Firefly–Artificial Neural Network (Firefly–ANN) computational intelligence model was developed to estimate the cost effectiveness and embodied CO2 of PT slabs with different design variables. To develop the dataset, several numerical models with various design variables, including the pattern of tendons, slab thickness, mechanical properties of materials, and span of slabs, were developed to investigate the sustainability and economic competitiveness of the derived designs compared to benchmark conventional RC flat slabs. Several performance measures, including punching shear and heel drop vibration induced by human activity, were used as design constraints to satisfy safety and serviceability criteria. The economic competitiveness of PT slabs was more evident in larger spans where the cost and embodied CO2 emissions decreased by 39% and 12%, respectively, in PT slabs with a 12-m span length compared to conventional RC slabs. Sensitivity analysis also confirmed that the cost and embodied CO2 emissions were very sensitive to the slab thickness by 86% and 62%, respectively.

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.

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.

Sendai Mediatheque embodies a new concept of space structure. The complex includes an art gallery, library, and media center. The 32 m high building is arranged over 9 levels, 2 below and 7 above ground. Each floor plan is 50 m square. The total floor area is 21 500 m2. It consists of two elements of “plate” and “tube”. The “plates” are six flat slabs. “Tubes” are 13 treelike columns that vertically penetrate the plates. These are the flexible structural members which also act as the vertical traffic line and as the space where energies flow. As a new model of future architecture, a minimal and pure structural system which contains those concepts such as clear tubes with HP-shape’s latticed shell by slender steel pipes for the main structure, extremely thin plates with steel sandwiched structure, and earthquake-energy absorbing system setting at the basement was proposed.