Evaluation of Carbon Dioxide Emissions amongst Alternative Slab Systems during the Construction Phase in a Building Project

The environmental impacts of the construction stage should be considered since a large amount of building materials are used to construct a building at this stage. Studies on the improvement of construction techniques or the application of newly developed construction methods for reducing the environmental impacts are relatively scant compared to other topics of studies. This study aimed to assess and compare the environmental impacts of the ordinary solid slab, the flat plate slab and the voided slab system during the construction phase. A process-based quantitative model was adopted to evaluate the environmental impacts and the comparative results were analysed to demonstrate the significant characteristics of the environmental impacts of the construction of slab in a building. The assessment results show that the environmental impacts from the ordinary solid slab are the highest and the voided slab system is the lowest among three slab systems. As the slab system of the studied building was replaced, it was shown that the environmental impact indicators showed the decreased tendency. Based on the results of environmental impact reduction from the ordinary solid slab, the flat plate slab and the voided slab system, the voided slab system would have the least environmental impact in all indicators.

The construction industry not only consumes a lot of energy but also emits large volumes of carbon dioxide. Most countries have established target reduction values of the carbon dioxide emissions to alleviate environmental burdens and promote sustainable development. The reduction in carbon dioxide emissions in the construction industry has been taking place in various ways as buildings produce large quantities of the carbon dioxide over their construction life cycle. The aim of this study is to assess and compare the carbon dioxide emissions of an ordinary reinforced concrete slab and the voided slab system applied to a case study involving a commercial-residential complex building in South Korea. Process-based life-cycle assessment (LCA) is adopted to compute the carbon dioxide emissions during the construction phase, which includes all processes from material production to the end of construction. The results indicate that the total CO2 emissions are 257,230 and 218,800 kg CO2 for the ordinary reinforced concrete slab and the voided slab system, respectively. The highest contributor to CO2 reduction is the embodied carbon dioxide emissions of the building materials, which accounts for 34,966 kg CO2. The second highest contributor is the transportation of the building materials, accounting for 3417 kg CO2.

The construction industry is one of the main contributors to the production of large volumes of greenhouse gases, since it consumes a large quantity of energy and construction materials. The purpose of this research is to assess the environmental impacts and economic efficiency of the voided slab system compared to the ordinary reinforced concrete slab. A life cycle assessment (LCA) and the total cost of construction were calculated to evaluate the performance of both slab systems. Additionally, the total costs of construction for both cases were determined based on the unit price of the building materials. The results of this study indicate that manufacturing building materials contributes most to the total GHG emissions where concrete is responsible for nearly 1/2 of all emissions. Additionally, forms are the second largest contributor of the total GHG emissions and account for nearly 40% and 15% of emissions for the ordinary reinforced concrete slab and the voided slab system, respectively. This study verified that the voided slab system indicated better environmental performance than the ordinary reinforced concrete slab. The total GHG emissions of the ordinary reinforced concrete slab were 256,599 and 13,989 kg·CO2·eq, for concrete and forms, respectively. Additionally, the total GHG emissions of the voided slab system were 224,945 and 12,211 kg·CO2·eq. The reduction of GHG emissions from Case 1 for aboveground floors and Case 2 for underground parking was 12.3% and 12.7% over the ordinary reinforced concrete slab, respectively. The economic efficiency of the ordinary reinforced concrete slab and the voided slab system were assessed by comparison of the total costs of construction. This showed a total cost reduction of 12.3% and 11.2% for the case of applying the voided slab system to the aboveground floors and underground parking, respectively. Thus, replacing the ordinary reinforced concrete slab by the voided slab system in the aboveground floors and the underground would make it possible to decrease not only the emissions of GHG, but also the cost of construction.

The use of flat plate slab is gaining much popularity amongst architects, because the flat plate slab system provides a way for the architect to achieve the concept of high and completely flat ceiling with no beam. As we know that, slab is one of the largest members consuming concrete, when the load acting on the slab is large or clear span between columns is more, the slab thickness is on increasing. It leads to consume more material such as concrete and steel, due to that self-weight of slab is increase. To avoid these disadvantages various studies carried out and researchers suggest voided flat plate slab system to reduce the self-weight of the slab. In this paper various parameters of the voided and solid flat plate slabs is calculated to compare the both systems. To evaluate the performance of the R.C.C voided and solid flat plate slabs, modelling of slabs is carried out using SAP 2000 having span ranging from 6x6 m to 14x14 m of 4x4 bay in both direction with thickness of the slabs 280 to 600 mm. The results drawn from the SAP 2000 are Reaction, Deflection, Moment and Reinforcement required for the voided and solid flat plate slabs. I. Introduction The flat plate floor systems are commonly used in multi-storey buildings, because flat plate floor system present advantages from technical and functional point of view. The self-weight of slab can reduce by replacing the middle height of the cross section of slab with void former. Here, to carry out the parametric study of voided flat plate slabs, different size of hollow void former( 180 to 450 mm ) is consider for various cases of slab thickness ( 280 to 600 mm). The modelling of voided flat plate slabs is carry out same as traditional flat plate slabs by applying the stiffness multiplication factor and modified self-weight of the voided flat plate slabs. The stiffness multiplication factor can be derived from the calculation of second moment of inertia of voided slab and solid slab.The other necessary checks are also done to prove that the voided slab can de model as solid flat slabs with necessary adjustment in certain parameters. The SAP 2000 results show that the behaviour of the voided flat plate slabs is almost same as that of solid voided flat slab in same condition. II. Reaction The main purpose of to carry out results for reaction is to confirm that the methodology that was adopted to perform the study of voided and solid flat slab is acceptable or not. It means that applied stiffness multiplication factor and modified self-weight of the voided slabs are correct or not. To perform the study, for different cases of voided and solid flat slabs are model in SAP 2000 ranging from 6x6 m to 14x14m having thickness 280 mm to 600 mm with spherical ball diameter 180 mm to 450mm respectively and slabs having 4 bays in both direction. For the punching shear criteria, the portion around the column is designed as the solid flat slabs without hollow void former. The results are taken at the centre of the slab considering only gravitational load.To validate the results of Reaction taken from SAP 2000 for voided flat slab, the numerical calculation is carry out of voided slab and the results are shown in Table -1. The Comparative results of reaction for voided and solid Flat slabs are shown in Table -2. The results have revealed that reaction of solid flat slab is higher than that of voided flat slab because of higher self-weight. Moreover, the values of reaction taken from SAP 2000 and by numerical calculation of interior bay are same for voided flat slab. From results it may be conclude that the methodology, which adopted to get the results are acceptable. Table -1 Result for validation of Reaction Slab Thk (mm) Ball Diameter (mm) Span (m) Reaction (KN)

Punching shear behavior of concrete flat plate slab reinforced with carbon fiber reinforced polymer rods

이 연구는 도넛형 중공형성체를 사용한 이방향 중공슬래브의 일방향 전단 성능에 관한 연구이다. 최근 건물의 고층화 및 장경간화로 인하여, 다양한 자중 저감형 슬래브 공법에 대한 연구가 진행되고 있다. 이방향 중공슬래브 시스템은 구조성능 저하를 최소화하면서 자중을 효율적으로 줄일 수 있는 시스템으로 알려져 있다. 하지만 기존 연구에 따르면 이방향 중공슬래브는 일반 RC 슬래브에 비해 낮은 전단강도를 가지고 있으며, 이는 중공형상 및 중공형성체 재료에 의해 영향을 받는 것으로 보고되고 있다. 또한 현재의 설계기준은 이방향 중공슬래브의 일방향 전단강도에 대해 명확한 기준을 제시하지 못하고 있다. 도넛형 이방향 중공슬래브의 일방향 전단강도를 확인하기 위하여, 총 4개의 전단강도 실험체를 제작/실험하였다. 그 중 한 개의 실험체는 기준 RC 실험체이고 나머지는 모두 중공슬래브이다. 변수는 도넛형과 비도넛형 두 가지의 중공형상 및 일반 플라스틱과 유리섬유 강화 플라스틱 중공형성체로 설정하였다. 실험 결과, 중공형상과 재료에 따라 이방향 중공슬래브의 전단강도는 차이를 보임을 확인할 수 있었다. 또한 이 결과를 바탕으로 기존의 구형 중공슬래브의 일방향 전단강도 산정시 사용되는 유효단면 산정법의 도넛형 이방향 중공슬래브 적용에 대한 문제점을 도출하였다.

Construction waste generation along with the extensive consumption of natural resources has propelled researchers to investigate effective measures for minimising the waste. While several studies have shown that the structural design would be an influencing factor on the carbon dioxide emissions of a building, there is a lack of studies to corroborate the effect of different structural systems to generate waste during the construction stage. This article seeks to bridge some of the knowledge gaps regarding the waste generation from different structural systems during the construction phase in a building project in South Korea and demonstrate its potential for waste reduction. In this study, the amount of waste generation during the construction phase was calculated based on the quantities and the material loss rate of each building material to estimate the quantity of construction waste by the changes in the application of different structural systems for the slab of the studied model. The total waste generation during the construction phase of the different slab systems shows that the solid slab system produces the largest amount of construction waste, which is 101,361.385 kg. On the other hand, the void slab system generates 87,603.958 kg of the construction waste, which is the lowest amount among the four variables of this study. The additional purchasing costs due to the loss of construction materials indicate that the solid slab system would require 80,709.76 USD, which is the highest value of the four variables in this study. The void slab system would cost USD 50,054.12 for additional materials purchasing costs, which is approximately 38% lower than the solid slab system.

This paper presents the flexural capacities of R.C.two-way hollow flat slabs with plastic voids. Recently, various types of slab systems which can reduce the self-weight of slabs have been studied as the height and span of building structures rapidly increase. To verify the flexural behaviour of this voided slab such as flexural stiffness, ultimate load, deflection, stresses and concrete compressive strain were studied.FEM model was created in ANSYS workbench 2022 for both conventional solid flat slab and voided slab. U-Boot beton from “daliform group building innovation Italy” was used as void former in this study. The dimensions of U-boot is 520×520mm and with 180mm and 160mm height. Dimension of FEM slab model is 8500×8500 mm with 500×500 column support at all four corners. Three different slab of 280mm, 300mm and 320mm was created. In addition, manual analysis of solid slab and voided slab was carried out using direct design method as per IS-456(2000). And further, design is checked to verify that it satisfies all design and serviceability criteria given as per IS-456(2000).Results obtain via theoretical calculation and FEM model simulation for both solid and voided slab were compared. The aim of this paper is to discuss and compare flexure behaviour of solid slab and voided slab and to study changes in inertia, stiffness and reduction in weight, of the slab by void formation.

The flat slab is gaining popularity among architects. The flat plate slab provides a way for architect to achieve completely flat ceiling with no beam protrusion. There is also improvement in the construction speed and cost savings from using this system which requires only simple formwork. But when load acting on the slab is large or clear span between columns is more so it is required to increase the slab thickness; hence the self –weight of slab is increased due to increased volume of slab and also more amount of steel is required to resist this increased weight of slab. Voided slabs eliminate concrete where it isn’t needed and the subsequent weight reduction due to this eliminated concrete makes longer span possible. In this study the design process for flat plate slab is compared with voided slab lightened with U-Boot Beton through a design comparison of total slab area 40m by 40m having panels of 10m by 10m and also the deformation of both type of slabs is analysed by using ETABS software.

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.

The post-tensioned (PT) flat plate slab system is commonly used in practice, and this simple and fast construction method is also considered to be a very efficient method because it can provide excellent deflection and crack control performance under a service load condition and consequently can be advantageous when applying to long-span structures. However, a detailed design guideline for evaluating the lateral behavior of the PT flat plate slab system is not available in current design codes. Thus, typical design methods used for conventional reinforced concrete (RC) flat plate slab structures have inevitably been adopted in practice for the lateral load design of PT flat plate structures. In the authors\' previous studies, the unified equivalent frame method (UEFM) was proposed, which considers the combined effect of gravity and lateral loads for the lateral behavior analysis of RC flat plate slab structures. The aim of this study is to extend the concept of the UEFM to the lateral analysis of PT flat plate slab structures. In addition, the stiffness reduction factors of torsional members on interior and exterior equivalent frames were newly introduced considering the effect of post-tensioning. Test results of various PT flat plate slab-column connection specimens were collected from literature, and compared to the analysis results estimated by the extended UEFM.

With the ongoing modern trends of the construction industry, slab systems like flat slab and post tensioned slabs are widely used in the construction. Flat and post tensioned slab are widely favored by architects and clients for aesthetic reasons. They also do possess a huge advantage structurally over conventional slab arrangement such as Less depth of the slab is required , increasing the floor-to-floor height , longer spans are possible , no beam projections , reduced self-weight of the building and many more. But it comes with its own disadvantages as well such as Brittle punching (shear) failure. Which requires additional reinforcement along the connections of column and slab. Which increases the longitudinal steel required. Slab – column connections are the first point of yielding in higher seismic zones with buildings without lateral load resisting system (LLRS). In higher seismic zones the slabs can resist only the gravity loads and can’t resist the lateral dynamic loading and hence may require additional lateral load resisting system (LLRS) to resist lateral loads such as seismic and wind loads. Thus it becomes essential to study the seismic behavior of conventional slab , flat slab and post tensioned slab systems in high rise RCC structure with and without various LLRS ( lateral load resisting system).This study is aimed to study various literatures related to effects of lateral loads on flat and post tensioned slab system and different LLRS (lateral load resisting system) to make the structure more resistant and economical against such lateral loads considering parameters like story displacement , base shear , stiffness of the connections and time period.

Many studies use life-cycle assessment (LCA) as a tool to quantify the environmental impact of buildings. Most of these studies have focused on the maintenance and operation phases of construction projects, which account for the largest part of energy consumption during the life cycle of buildings. However, the construction phase may cause significant environmental impacts, so a detailed analysis on the construction phase is required to conduct a more accurate assessment of the energy consumption and environmental impact of a building's entire life cycle. To assess energy consumption and greenhouse gas (GHG) emissions, this study developed a model using process-based LCA and input-output (I-O) LCA. This study divided the construction phase into material manufacturing, transportation, and on-site construction, and applied an appropriate methodology for each part. The analysis of an apartment building project using the developed model showed that the material manufacturing stage had the largest amount of energy consumption and GHG emissions. Quantitatively, material manufacturing, transportation, and on-site construction phases were responsible for 94.89, 1.08, and 4.03% of energy consumption, and 95.16, 1.76, and 3.08% of global warming potential, respectively. It is believed that the developed model would allow a more accurate assessment of energy consumption and GHG emissions during a building's construction phase. DOI: 10.1061/(ASCE)ME.1943-5479.0000199. © 2014 American Society of Civil Engineers.

This study, with the life-cycle approach, examines the carbon footprint of a residential tower in the Tehran Metropolitan City in the construction phase. This paper assessed all sources of carbon emissions in the construction phase, including emissions from manufacturing and extraction of building materials, transportation of building materials, construction equipment, vegetation cover around the building, and transportation of construction waste. According to the results, the highest amounts of carbon footprint were estimated at 83% and 14%, which were, respectively, related to the emissions from transportation of materials and construction wastes. The emissions from the construction phase accounted for the 3% of the total footprints. Also in the manufacturing process of building materials, the highest contributions in CO2 emissions were 78%, 10%, and 6%, belonging to concrete, rebar, and cement mortar, respectively. The results of this study can be used as a criterion for comparing and assessing the preventative measures to reduce and manage CO2 emissions in the construction of similar buildings. The approaches that exist for reducing CO2 emissions in construction include management of amount of waste generated and choosing the types of environmentally friendly building materials and providing materials from factories near the site.

In the world of construction, aesthetic has become an important factor that must be considered. The aesthetic elements consist of wholeness, prominence and balance. However, aesthetic values can be influenced by several factors, namely economic, social, cultural, technological, ergonomic and psychological factors and this cause that in commercial development or the building that use slab system for foundation is used greatly affects it in terms of aesthetics and also cost effectiveness. The author's purpose of doing this research is to analyse the efficiency of volume in concrete and deflection between Flat Slab system and Waffle slab system. This research uses a case study at the Pasir Putih Convention, Batam, Indonesia. The analysis is done with ETABS software based on the local standards or known as Indonesia National Standard (abbreviated SNI). The choice of a slab system in a development is very important, especially if the building or construction is categorized as commercial structure. Based on the data obtained by researchers in terms of economics and deflection, Waffle Slab System is the right choice, meanwhile in terms of ease construction Waffle Slab System will be the secondary choice than Flat Slab, Since Flat Slab is more ease of framework installation than Waffle Slab.