Waffle Slab Research Articles

Delivering Sustainable Housing through Material Choice

Increasing importance is being placed on sustainability worldwide to limit climate change’s effects. In New Zealand, a sizeable increase in demand for housing is driving a residential construction boom, with new dwelling consents increasing yearly for the last decade. The New Zealand Government’s commitment to sustainability has become legislation through the Climate Change Response (Zero Carbon) Amendment Act 2019. Therefore, the next stage is how the construction industry can limit and reduce its carbon emissions through one of the strategies, namely material choice. This study was intended to examine the influence of various building materials on climate change and to identify how more sustainable home construction and design in New Zealand may contribute to the government’s 2050 emissions reduction targets. A life-cycle assessment (LCA) was used in this study to investigate the global warming potential (GWP) produced by five case study houses and various material options for building envelope components. The study focused on the environmental impact of materials with high usage in industry and potential new materials that have shown an ability to conform to the New Zealand Building Code standards. It was found that case study House 1 (with timber flooring founded on senton piles with concrete footings, a timber frame, plywood wall cladding, and metal roof cladding) and House 2 (with a concrete waffle slab, a light steel frame, masonry wall cladding, and metal roof cladding) had the lowest GWP emissions compared to the other case study houses, with 631.13 and 633.16 kg CO2eq/m2, respectively. However, it should be noted that all the case study houses were not similar in size and design. In addition, the study investigated the different building envelope material options for the foundation, wall cladding, framing, and roof cladding. The study found that some new materials or materials that are not common in New Zealand could be used as an option for the housing envelope by having lower carbon emissions, such as 3D-printed concrete blocks compared with brick and concrete masonry for wall cladding systems.

USE OF ANALYTICAL METHOD FOR CALCULATING STIFFNESSES OF STRAIGHT WAFFLE SLABS. PART 2. CALCULATION USING RELATIVE STIFFNESS OF BEAMS

Introduction. The analytical calculation of reinforced concrete waffle slabs calls for the determination of the components of total load on joists, depending on the dimensions of spans and the rigidity of central joists. In the case of slabs having rectangular coffers of various orthogonal rigidity, this theory leads to results differing significantly from those obtained by the finite element method. The waffle slab comprises a ribbed slab, characterized by cylindrical or relative beam stiffness.Aim. This article discusses the accuracy of the calculated span bending moments in the joists of straight reinforced concrete waffle slabs using the span dimensions and relative stiffness of joists in analytical formulas.Materials and methods. The work was carried out by comparing the bending moments for joists in the central zones of straight waffle slabs obtained analytically and using the SCAD software by the finite-element method. Square or rectangular in plan, 13 slabs having different aspect ratios of waffle were considered. A T-beam and girder construction were used in the computer model.Results. The maximum deviations of the bending moments obtained by the analytical calculation from the computer-aided method amount to: -0.6% for a square slab having square coffers, from -2.8 to +2.5% for a square slab having rectangular coffers, from -6.2 to +2.0% at a span ratio of Lmax/Lmin ≤ 1.5 for a rectangular slab having rectangular coffers, and from -7.3 to +4.8% for those having square coffers. For rectangular slabs having any coffers at a span ratio of Lmax/Lmin ≥ 1.75, a computer-aided calculation revealed that the plot of bending moments in the long-side direction deviates from parabola.Conclusions. The use of the span dimensions and relative stiffness of joists in the analytical formulas for calculating straight hinge-supported reinforced concrete waffle slabs allows the values of bending moments to be obtained that are in agreement with those obtained by the finite element method.

Seismic response evaluation of waffle slab with and without bracing system using time history analysis

In the analysis and design of structures, seismic ground motion is a significant factor. Seismic criteria consideration is necessary for serviceability and feasibility of existing as well as new structures. Time History analysis is the one in which base is subjected to a specific ground motion and dynamic response of structure is analysed at each increment of time. The bracing system increases the structure’s resistance to lateral loads by transferring load from the frame to the braces. This study uses the ETABS software to do a time history analysis on a G+4 RCC building with a waffle slab and an X-type bracing system. For designing purposes, the IS 456-2000 code is thought about. According to IS 875-part 1, live loads are measured, and IS 1893-2016 earthquake analysis is carried out. For this structure, a number of factors are analysed, including storey drift, base shear, storey stiffness, and storey displacement, among others.

Flexural Behavior of Steel–UHPC Composite Beams with Waffle Slabs under Hogging Moment

Flexural Behavior of Steel–UHPC Composite Beams with Waffle Slabs under Hogging Moment

Comparative study of numerical methods used in prediction of post-crack behavior of waffle slabs

Comparative study of numerical methods used in prediction of post-crack behavior of waffle slabs

Recital Hall into existing structure limited height space

Renovations for a college Fine Arts program desired to reincorporate multiple art departments that had become scattered over various locations throughout campus into an existing mid-century architecture legacy building. Included in the renovation program is a 130 seat Recital Hall, Instrumental Music Labs, and Commercial Music Recording program. The particular small rooms challenge presented is that the 130 seat Recital Hall must fit within an existing concrete waffle slab structure with a height of 17 feet from floor to bottom of structure and a total room volume of only 30,000 cubic feet. This presentation will walk through the challenges of providing an acceptable room acoustic environment for recitals amongst the other design challenges of ADA accessibility, sound separation to other arts programs, modern MEP services and requirements, and limitations of existing structural capacity.

Comparative Study of Waffle Slab with Bracing System and Conventional Slabs without Bracing System

Abstract: The analysis and design of structures are influenced by earthquake ground motion. The objective of this work is to analyse a commercial building with two different slab configurations, including conventional slabs, grid/waffle slabs and structures with bracings. The bracing system allows load to be transmitted from the frame to the braces, increasing the structure's capacity to withstand lateral loads. Time history analysis is performed in order to study the impact of seismic loads on structures with two different slab layouts using ETABS software. Storey drift, stiffness, joint displacement and storey displacement are among the parameters that have an influence on a structure's performance and are vital in determining how building will respond under seismic loads and other load combinations. IS 456-2000 code is taken into consideration for designing purpose. Live loads are taken in accordance to IS 875-part 1 and earthquake analysis is performed according to IS 1893-2016 Part 1. Results are depicted in the form of graphs and tables in the research paper. The outcome demonstrates that waffle slab with bracing system in terms of displacement and drift shows better performance, in contrast to alternative slab arrangements utilized in the seismic evaluation of the buildings.

Use of analytical method for calculating stiffnesses of straight waffle slabs

Introduction. The analysis of analytical and computer-assisted calculations of waffle slabs shows that, depending on the established finite-element model and structure geometry, the forces in beams can vary significantly. As a rule, the analytical model is used as a reference when comparing bending moments. Examples available in the literature show that regardless of the slab geometry, the stiffness of individual central orthogonal beams or conditionally selected beams is used in the calculations when determining structural loads.Aim. In this work, the accuracy of resulting forces in the beams of straight waffle slabs was assessed using the stiffness of individual beams in the analytical calculation.Materials and methods. The work was carried out by comparing the bending moments obtained analytically and in the SCAD software by the finite-element method for beams having various stiffnesses in the central zones of straight waffle slabs. 12.0 × 12.0 m slabs square in plan having different aspect ratios of waffle were considered, as well as slabs having square 1.5 × 1.5 m waffles and different aspect ratios of spans. A T-beam-and-girder construction was used in the computer model.Results. The values of bending moments of slabs square in plan having square caissons calculated analytically and using the computer-assisted finite-element method coincide, being a particular case. The bending moments calculated analytically and using the finite-element method for rectangular slabs or slabs having rectangular caissons differ. As the ratio of the span or caisson sides increases, these deviations increase.Conclusions. In the general calculation, using the stiffnesses of individual central orthogonal beams or conditionally selected beams for the analytical determination of forces in the beams of straight waffle slabs leads to erroneous results.

Edge punching shear of waffle slabs subjected to moment parallel to the slab's free edge

The test results of five one-tenth scale micro-concrete waffle slabs subjected to edge punching shear in the presence of moment transfer parallel to the slab's free edge are presented. Although the observed punching failure mechanism of the waffle slabs was found to be very similar to that of a flat slab, the shear capacity was reduced because some of the potential failure surface is lost when it extends into the waffle section. Since the current codes of practice do not specifically consider the punching shear mechanism of waffle slabs, comparisons with test results revealed that the application of various codes overestimated the punching capacities of waffle slabs. An upper-bound plasticity theory model was developed to predict the punching shear failure load. The proposed model assumes concrete to be a perfectly rigid plastic material with the modified Mohr–Coulomb failure criterion. The model showed good agreement with the test results.

Comparative Study of Conventional Slab, Flat Slab and Waffle Slab by using Finite Element Method

Abstract— The slab is the main component of the structure. There are different types of slab used in different structure and gives better appearance to the structure. In this project, three type of slab to be used. The comparative study of Conventional slab, flat slab, and waffle slab under seismic condition to be analyzed. An effort has been made to evaluate the study between Conventional slab, flat slab, and Waffle slab for G+10 story building. This type of slab has been analyzed and designed by ETABS software. The plan of waffle slab plan is done in such a way in order to accomplish better burden dispersion. The near investigation of waffle slab with flat Slabs and conventional slab and features the benefit waffle slab have over flat Slabs and conventional slab. The parametric studies comprise maximum lateral displacement, story drift, and axial forces generated in the column due to slab. Keywords— ETABS, Conventional Slab, Flat Slab, Waffle Slab, Story Displacement

An Optimal Cost Estimation Practices of Fuzzy AHP for Building Construction Projects in Libya

This paper analysis and reviews the construction projects in Libya. In Libya, construction projects often face challenges due to the lack of proper information and data in cost-estimation methods. The primary goal of this paper is to demonstrate the estimation of construction costs using various methods. An optimization strategy based on a well-known robust algorithm The Fuzzy AHP technique is used to estimate the best roof structure choice based on cost rank among one or two-way flat slab, post-tension slab, pre-tension slab, waffle slab, and hollow core slab. The roofs were created employing five main factors that were implemented in a real-world situation in the Libyan building industry. The cost of materials, labor, machinery, transportation, and trash on site were all considered. Research findings show that the models can assist decision-makers in determining the cost rank of roof selection. When a range of methods are applied and compared to guarantee that this is the best option. This research study must be taken seriously when estimating and managing the contract and length of highway construction projects in the early stages of project development so that the time difference at the end of the project can be kept to a minimum by decision-makers when choosing the roof with the lowest cost. Doi: 10.28991/CEJ-2022-08-06-08 Full Text: PDF

Analisis Perbandingan Kinerja Seismik dari Struktur Gedung dengan Pelat Konvensional, Waffle Slab, dan Flat Slab

Indonesia is a country with high earthquake risk because it is located in the path of the most active earthquake in the world. It makes Indonesia situated in a region with a high earthquake intensity. The study aimed to determine the seismic performance levels of building structures with conventional slabs, waffle slabs, and flat slabs with the time history analysis method. There are three models of structures studied, namely building structures with conventional plates, building structures with waffle slabs, and building structures with flat slabs, with a 5-story structure system, where the longest and shortest span has the same size of 20 m and the height of each level 4 m. This study showed the largest displacement was 235.82 mm in building structures with waffle slabs and the smallest displacement was 146.49 mm in building structures with flat slabs. The largest drift is 0.012 on a building structure with a waffle slab, and the smallest drift is 0.007 on a building structure with a flat slab. The level of seismic performance produced from all three types of structures varies from immediate occupancy (IO) to damage control (DC).

Review Paper on Studying the Behavior and Comparison of Flat Slab and Waffle Slab System in Same Building under Seismic Condition

Abstract: There has been an associated increasing demand for the construction of tall buildings thanks to associate everincreasing urbanization and increase in population. The modeling of such earthquake and wind masses has to be done, therefore evaluating the behavior of the structure with a transparent perspective of the injury that's expected. to research the structure for numerous earthquake and wind intensities and so perform checks for numerous criteria at every level has become vital apply for the last few decades. The principal objective of this project is to research flat blocks and waffle slab victimization ETABS, to urge the optimum style. The look involves load calculations and analyzing the full structure by ETABS. the look strategies utilized in ETABS analysis square measure Limit State style orthodox to Indian customary Code of apply. ETABS options have a state-of-the-art computer program, mental image tools, powerful analysis and style engines with advanced finite component and dynamic analysis capabilities Keywords: Flat slab, Waffle slab, Seismic condition, Flat slab with a drop, flat slab without a drop, ETABS

Numerical and theoretical studies on shear behavior of steel-UHPC composite beams with waffle slab

UHPC waffle slab was proposed to utilize the excellent material properties of UHPC and improve the rigidity of bridge deck. The flexural behavior of steel-UHPC composite beams with waffle slabs (SUCBWS) has been studied recently while the shear behavior of SUCBWS is still limited. This paper aims to supply the gap in the research system of mechanical properties of the novel bridge deck system. Based on the experimental study of four SUCBWS, a three-dimensional finite element model (FEM) was developed to investigate the shear behavior of SUCBWS. Extensive validations of the numerical analyses against the reported tests proved that FEM is reasonable. Meanwhile, the shear working mechanism of SUCBWS was analyzed. A subsequent parametric study was conducted to investigate the effects of shear span ratio, yield strength of steel, degree of shear connection, the ratio of rib height to top flat plate thickness and adding haunch at the rib-to-plate interface on the shear behavior of SUCBWS. Results show that shear span ratio and degree of shear connection present an obvious influence on ultimate bearing capacity, stiffness, ultimate deflection and failure mode of the composite beam. The shear span-to-depth ratio increased 1.34 to 3.14 resulted in a decrease in stiffness and shear strength while an increase in ultimate deflection. The increase of the degree of shear connection (from 0.5 to 1) improved the stiffness and ultimate bearing capacity but reduced the ultimate deflection. Adding the haunch at the rib-to-plate interface can significantly improve the integrity and decrease the risk of longitudinal splitting failure of the UHPC waffle slab. The high-strength steel can match well with the UHPC waffle deck so as to improve the ultimate bearing capacity of SUCBWS. The increase of the ratio of rib height to top flat plate thickness showed a limited influence on shear behavior of composite beams and the value of 3 is recommended for the design of SUCBWS. Meanwhile, the shear composite action coefficient, shear contribution coefficient of top flat plate and ribs were proposed to develop the theoretical models for predicting the shear capacity of SUCBWS and providing a reference for the design of SUCBWS. Besides, the effect of the haunch size at the rib-to-plate interface on the mechanical performance of SUCBWS should be further quantitatively analyzed.

Seismic Response of Large span slab in Horizontal Setback Building

Abstract: The demand for multi-storey buildings is increasing day by day. Residential plus commercial building is mainly used for wide span needs. Wide span required for Flat slab, Waffle slab and ribbed slab stands An excellent option for architects when larger openings in a building need to be covered with as few columns as possible. The use of different types of plates is developing as a new trend and is becoming a major challenge for structural engineers. Therefore, it is necessary to study about its structural behavior. The project is carried out under earthquake zone III under the earthquake analysis of G+9 storey building. For this study, four different types of large span slab structure are modelled in C-shape (Horizontal Setback Building) having 10-stories i.e. G+9 storied buildings with 3.50 meters height for each story is modelled and analysed. The plan area of all four buildings is same i.e. 2859 square meters (49.50 m x 82.50 m) each. These buildings were designed in compliance with the Indian Code of Practices for earthquake resistant design of buildings. Base of the building were fixed. The square sections are used for structural elements. The height of the buildings is considered constant throughout the structure. The buildings are modelled using ETABSvr.2016. Keywords: large span slab, ETABSvr.2016, Horizontal Setback Building, Flat slab, Waffle slab and ribbed slab

Seismic Response of Large span slab in Horizontal Setback Building: A Review

Abstract: The demand of multistory Building is increases day by day. The residential plus commercial building predominantly used for the need of large span. The large span is needed for Flat slab, Waffle slabs & ribbed slab stands as an excellent option for architects when larger spans in a building has to be covered with the least possible number of columns. The use of different types slabs are evolving as a new trend and are becoming a big challenge for structural engineers. Therefore it is necessary to study about its structural behavior. The paper is review the behavior of different types slab for large span type of building. Final aim to gets the suitable type of slab for large span for effective manner. It is found that very less work is taken setback building with large span, it is required to analysis on the setback building with large span. Keywords: Flat slab, Waffle slabs, ribbed slab, multistory Building, large span.

Seismic Analysis of Commercial Building with Grid/Waffle slab using ETABS

Abstract: In This I have studied the seismic response of various types of slab in commercial buildings and their seismic behavior is studied. As we know every year uncountable number of earthquakes occur at different places, that means, small movements of tectonic plates occur all the time causing earthquakes. A seismic resistant designed building can provide safety for more people. slabs and roofs needed more columns if we design seismic resistant design but at some places like airport, shopping mall, commercial building more column can create some problem. To overcome this problem seismic design of grid slab or waffle slabs was comes out. Grid /Waffle slab consists of Concrete beams spaced at uniform intervals in perpendicular directions which are monolithically casted with slab and they are more safe in earthquake situation as comparison of to normal conventional slab. Keywords: Grid Slab, Earthquake Load , Response Spectrum , Storey Drift, Storey Displacement , E-Tab 2018 , Base Shear, Time Period , Mode Shapes.

Comparative Study of Tube in Tube Flat Slab with Tube in Tube Waffle Slab, Structures Under the Sesmic Loads

Abstract: The tube in tube structure is one of the type that is been broadly used as structural system for tall structures. Considering the lateral loads due to the seismic force it gives more stiffness and gives more strength to the high-rise structures. Lateral loads are shared between the inner and outer tubes our aim is to make the structure stiff by its connectivity and comparing them by providing drops to the waffle. By adding tube in tube to the flat slab and waffle slab, concept is they both does not have the beams such that to know the comparison of both the models. This both models have been designed using e-tabs software and the dimensions, limitations are been taken from the provision Indian standard code book. Keywords: High-rise building, tube in tube, Response spectrum analysis.

Waffle Slab Behavior Subjected to Blast Load

Over the previous years, the use of structure roof systems which can be implemented with long column spans has been welcomed by manufacturers. One of the most widely used roofs is the waffle slab system. Therefore, by reviewing previous studies in the field of roof collapse in reinforced concrete structures under blast, the absence of studies on the performance of waffle slab and comparing its behavior with blast affected RC slabs is observed. Laboratory simulation of this problem requires high cost, high accuracy in model building and much time. In this study, after preliminary model validation with experimental research and two numerical studies in LS-DYNA software, the behavior of waffle slab subjected to blast load and compare its performance with RC slab is investigated. It should be noted that because the blast load is applied to the structure in a very short time, it has a high loading rate. Therefore, the strain rate effects on concrete and reinforcement are considered for achieving real material behavior. The identical volume of concrete and reinforcement used in all roofs is considered in order to evaluate and compare the behavior of the roofs reasonably. Then, the effect of the geometric dimension of waffle molds and the effect of the supporting condition on the Waffle slab responses are studied. Other parameter investigated in this study includes the effect of concrete compressive strength on the behavior of roof under blast load. The mass of the explosive and its distance from the roof surface are other parameters considered in this study. The effect of bar size on the behavior of the roof is also investigated. The results of this study are presented as diagrams and tables showing that given the same volume of concrete and reinforcement in the RC slab and the waffle slab, the central displacement of Waffle slab are reduced to a desirable level. This shows the better behavior of the waffle slab in comparison with the RC slab with the same volume of material under the blast load.

Evaluating the effects of different slab types on static and dynamic characteristics of structures

In this study, the effect of different types of slabs on dynamic characteristics of structures under the lateral loading was investigated. For this purpose, four different types of slabs namely, beamed slab, flat slab, one way ribbed (hollow core) slab and waffle slab have been modeled in buildings having 3, 4 and 5 storeys with the same geometric dimensions, in accordance to design and construction requirements (TS 500) and Turkish building seismic codes (TBDY, 2018). Seismic analysis calculations of the modeled buildings were done using the equivalent seismic load method. The assumed local soil class was taken from the geotechnical report as ZD. As a result of the analysis, natural periods, base shear forces, maximum horizontal displacements and relative storey drifts of the buildings were compared. Seismic analysis and calculations of the buildings were completed using SAP2000 finite element software.