Flat Slab Research Articles

Enhancement of flexural behavior of hybrid flat slab by using SIFCON

Abstract Flat slab systems are widely utilized in construction due to their versatility and efficient use of space. Nevertheless, they are susceptible to flexural failure, particularly in the tension zone. To address this issue, slurry-infiltrated fiber concrete (SIFCON) has been proposed as a solution owing to its exceptional strength and durability. This research examines the effect of utilizing SIFCON in the tension zone of flat slab systems to enhance their flexural performance. The study encompasses testing eight identical slabs, two of which were cast with normal concrete, while the remaining six were hybrid slabs incorporating SIFCON. The specimens were subjected to vertical loading to compare their flexural behavior and identify the optimal dimensions for the SIFCON layer. The slabs had identical dimensions but varied in reinforcement. Group A had a reinforcement ratio of ρ = 0.5%, whereas Group B had a ratio of ρ = 0.335%. All slabs had a constant thickness of the SIFCON layer of 20 mm in the tension zone but varied in the dimensions of the SIFCON layer (100, 50, 30%) from the slab dimensions. A square plate with dimensions (140 × 140 × 20) mm supported the load for all slabs. The load was applied gradually until failure, and the load–deflection curves were recorded for each slab. The result showed that using SIFCON in the tension zone improved the flexural resistance of flat slab systems. The hybrid slabs with SIFCON demonstrated higher ultimate loads and lower deflections than the control slabs that used regular concrete. In particular, the hybrid slabs with a 100% SIFCON layer exhibited the best results, with a rise in ultimate load of 179 and 100% for Groups A and B, respectively, compared to the control slabs. In addition, there was a significant decrease in deflection of 62.35 and 52.38% for Groups A and B, respectively, relative to the control slabs. The study found that the optimal combination of the SIFCON dimension was when the 50% slab dimension was covered and the reinforcing bar area for the hybrid reinforcement system was smaller.

Nonlinear analysis of the impact of openings on punching shear strength

AbstractReinforced concrete flat slab projects usually require openings close to the columns for electrical and hydraulic installations. Since such openings reduce the punching shear of slabs, a comprehensive study is needed. In this paper, numerical models of slabs tested in literature were elaborated upon, using the commercial software in finite elements DIANA. The physical nonlinearity of the materials was considered. After the calibration and validation of the numerical parameters related to concrete and reinforcement, 62 numerical models were created for performing a parametric analysis. The numerical analysis aimed to study the effect of openings close to the columns and verify the punching resistance reduction. In this parametric study, the main variables were the compressive strength of the concrete, the bending reinforcement ratio, the number of openings, and the distance from the openings to the column's face. Finally, the numerical results obtained were compared with the punching strength values provided by the main structural design codes, viz., NBR 6118 (2014), Eurocode 2 (2004), ACI 318 (2019), fib Model Code (2010), and the next generation of Eurocode 2, which are constantly questioned in academic papers regarding their safety.

Reshaping concrete

Less Economically Developed Countries (LEDCs) struggle to meet the demand for affordable housing in their growing cities. There are several reasons for this, but a major constraint is the high cost of construction materials. In LEDCs, material costs can constitute 60 to 80 percent of the total cost of residential construction. Nonetheless, their construction mimics the materially inefficient practices of the More Economically Developed Countries (MEDCs), which were developed to reduce labor over material costs. As a result, prismatic beams and flat slabs are often used despite their structural inefficiency. The mounting use of steel-reinforced concrete structures in LEDC cities also raises concern for the environmental costs of construction; construction accounts for 20-30 percent of LEDC carbon emissions. This research addresses these challenges with a flexible and accessible methodology for the design and analysis of materially efficient concrete elements that may reduce the economic and environmental costs of urban construction. Designed for the constraints of LEDCs, structural elements are optimized to reduce the embodied carbon associated with the concrete and reinforcing steel while resisting the required loads of a standard building structure. The optimization method includes a novel approach to 3D-shape parameterization, as well as a decoupled analytical engineering analysis method that accounts for the key failure modes and constraints of reinforced concrete design. This method is then built into an open-source toolkit, combined with machine learning for real-time analysis and visualization, and tested using lab- and full-scale prototypes. The goal of this research is to present several generalizable methods that are applicable and accessible to LEDC building designers. These methods can enable the design of concrete elements for multiple performance criteria such as structural behavior, acoustic transmission, and thermal mass. They can also enable an accessible design practice through machine learning, real-time iterative workflows, and visualization tools that include the end-user in the architectural design process. This paper provides a high-level overview of ongoing research that explores how materially efficient design methods might enable sustainable development through low-cost, low-carbon concrete structural systems for affordable housing in LEDCs.

Anisotropic structure of the normally-dipping and flat slab segments of the Alaska subduction zone: Insights from receiver function analysis

The complex tectonic setting of south-central Alaska is characterized by a transition from normally-dipping subduction of the Pacific plate in the west to near-flat slab subduction of the overthickened Yakutat microplate in the east. Many previous studies have characterized both the isotropic and anisotropic subsurface structure of this region, but only a few studies have characterized anisotropy using receiver functions. Here, we present anisotropy-aware receiver function analysis for two transects of permanent seismic stations in south-central Alaska, one covering a normally-dipping segment of the subduction zone, and one covering the adjacent flat slab segment. Beneath the normally-dipping segment, there is evidence for shearing and possibly serpentinization at the top of the slab in the shallow forearc, and for variation in mantle flow geometry with depth, possibly a result of oblique subduction and/or the adjacent flat slab segment, or an arc magmatism-related process. Additionally, there appears to be significant crustal deformation associated with the volcanic arc. We also identify significant crustal deformation and anisotropy along the flat slab segment, likely a result of the subducting Yakutat microplate, with crustal deformation geometry appearing to vary along the transect. There also appears to be evidence for water-rich conditions at the top of the flat slab, shedding light on the distribution of volatiles in a flat slab setting that lacks an active volcanic arc.

The Structural Behavior of Heat-Damaged Flat Slabs with Openings of Different Sizes and Locations

The Structural Behavior of Heat-Damaged Flat Slabs with Openings of Different Sizes and Locations

Effect of slab dimensions on the maximum stress and ultimate vertical load of a 15-story flat slab building

The research of flat slab structures requires more investigation into the full-scale analysis of steel flat slab structures under vertical loads. The impact of slab dimensions on the maximum stress of slabs and columns, as well as the ultimate vertical load at the linear elastic stage, has been examined using full-scale finite element models. The particular structures selected for the analysis are 15-story steel flat slab structures with various slab dimensions under the static vertical load and standard earth gravity. This research also involves: (1) the verification of stress singularity at the corner of cubic columns in the finite element model; (2) the discussion about the variation of maximum stress of slabs and columns as the floor changes, and the interaction of columns and slabs; (3) the validation of the vulnerability of slab-column connection.

Two-Way Slab Punching Shear Resistance: Experimental Insights into Basalt-FRP Bar as Flexural Reinforcement

This study seeks to experimentally evaluate the punching shear performance of two-way concrete slabs reinforced with conventional steel and basalt fiber-reinforced polymer (basalt-FRP) bars subjected to punching loading condition. Basalt-FRP bars offer high tensile strength and corrosion resistance but are understudied in two-way concrete slabs concerning punching shear. This study aims to fill this gap, with key implications for future structural design considerations. To achieve the objectives of the study, six large-scale square slabs were fabricated and subjected to a concentric load until failure. The parameters of the experiment included are the type of reinforcement used (either basalt-FRP or steel), the percentage of basalt-FRP used (ranging from 0.88% to 1.77%), the size of the basalt-FRP bars used (either 16 or 12 mm), and the concrete’s compressive strength (25, 30, and 35 MPa). The findings from the tests showed that incorporating basalt-FRP bars with one-quarter equivalent axial stiffness (ρ(Ef/Es)) to that of steel significantly enhanced the punching shear resistance of flat slabs, achieving approximately 65% of the capacity observed in steel-reinforced control sample. Moreover, increasing the amount of basalt-FRP bar reinforcement to half of the equivalent axial stiffness of steel had a substantial effect in improving shear strength, reaching approximately 89% of the capacity observed in the steel-reinforced specimen and concurrently reducing deflection during the failure. Additionally, the reinforcement type and concrete compressive strength played a crucial role in determining the ultimate load, failure modes, and crack propagation patterns. The study reveals discrepancies between experimental results and existing models for punching shear in FRP-reinforced slabs. Certain prevalent models prove to be conservative in their estimates, while others offer more accurate predictions, indicating the need for comprehensive model refinement. The investigation found that one model, encompassing the majority of variables affecting punching shear, exhibited the highest level of precision, with a slight adjustment recommended to enhance its accuracy further. This study suggests a sustainable, more durable way to reinforce concrete in bridges and high-rise buildings, potentially improving construction efficiency, enhanced service life, and potential updates to building codes.

Multi-Objective Optimization Design of FRP Reinforced Flat Slabs under Punching Shear by Using NGBoost-Based Surrogate Model

Multi-objective optimization problems (MOPs) in structural engineering arise as a significant challenge in achieving a balance between prediction accuracy and efficiency of the surrogate models, which are conventionally adopted as mechanics-driven models or numerical models. Data-driven models, such as machine learning models, can be instrumental in resolving intricate structural engineering issues that cannot be tackled through mechanics-driven models. This study aims to address the challenges of multi-objective optimization punching shear design of fiber-reinforced polymer (FRP) reinforced flat slabs by using a data-driven surrogate model. Firstly, this study employs an advanced machine learning model, namely Natural Gradient Boosting (NGBoost), to predict the punching shear resistance of FRP reinforced flat slabs. The comparisons with other machine learning models, design provisions and empirical theory models illustrate that the NGBoost model has higher accuracy in predicting the punching shear resistance. Additionally, the NGBoost model is explained with Shapley Additive Explanation (SHAP), revealing that the slab’s effective depth is the primary factor affecting the punching shear resistance. Then, the formulated NGBoost model is adopted as a surrogate model in conjunction with the Non-Dominated Sorting Genetic Algorithm-II (NSGA-II) algorithm for multi-objective optimization design of FRP reinforced flat slabs subjected to punching shear. Through a case study, it is demonstrated that the Pareto-optimal set of the punching shear resistance and cost of the FRP reinforced flat slabs can be successfully obtained. By discussing the effects of design parameter changes on the results, it is also shown that increasing the slab’s effective depth is a relatively effective way to achieve higher punching shear resistance of FRP reinforced flat slabs.

Seismic imaging of the Northern Andean subduction zone from teleseismic tomography: a torn and fragmented Nazca slab

SUMMARY The Nazca-South America subduction zone in Ecuador is characterized by a complicated along-strike geometry as the slab transitions from flat slab subduction in the south, with the Peruvian flat slab, to what has been characterized as ‘normal’ dipping subduction beneath central Ecuador. Plate convergence additionally changes south to north as the trench takes on a convex shape. Highly heterogeneous bathymetry at the trench, including the aseismic oceanic Carnegie Ridge (CR), and sparse intermediate-depth seismicity has led many to speculate about the behaviour of the downgoing plate at depth. In this study, we present a finite-frequency teleseismic P-wave tomography model of the northern Andes beneath Ecuador and Colombia from 90 to 1200 km depth. Our model builds on prior tomography models in South America by adding relative traveltime residuals recorded at stations in Ecuador. The complete data set is comprised of 114 096 relative traveltime residuals from 1133 stations across South America, with the added data serving to refine the morphology of the Nazca slab in the mantle beneath the northern Andes. Our tomography model shows a Nazca slab with a fragmented along-strike geometry and the first teleseismic images of several proposed slab tears in this region. At the northern edge of the Peruvian flat slab in southern Ecuador, we image a shallow tear at 95–200 km depth that appears to connect mantle flow from beneath the flat slab to the Ecuadorian Arc. Beneath central Ecuador at the latitudes of the CR, the Nazca slab is continuous into the lower mantle. Beneath southern Colombia, the Malpelo Tear breaks the Nazca slab below ∼200 km depth.

The Seismic Behavior of Buildings with Flat Slab Systems under Near-Fault Ground Motions

It is well known that structural displacement or ductility demands of structures subjected to near-fault ground motions are generally greater than ordinary ground motions. Therefore, the effect of earthquake records in the near region on the seismic behavior of structures has been widely studied in the last decades. Peak ground acceleration (PGA) is an important key parameter, which determines structural behavior. However, structural behavior depends on the distance of the structure to the fault zone, the ratio of peak ground velocity (PGV) to peak ground acceleration, the velocity pulse duration of ground motion, and the natural period of the structure. In this study, the seismic behavior of buildings with flat slab systems was investigated under near-fault ground motions. Linear time history analysis was performed for a 30-storey building designed according to TBEC-2018 using SAP 2000 finite element analysis software. Results were compared with the behavior of the building with a solid slab system. It is concluded that the ratio of PGV/PGA is very effective on the flat slab systems.

A Comparative Study of the Seismic Response of Different Concrete Slab Systems for a Multistory Building in Madinah

Seismic analysis is considered as an important aspect of the design of high-rise buildings, particularly in earthquake prone areas. The structural system choice can have a considerable impact on the building seismic response. The goal of this study is to compare the seismic behavior of multiple slab systems used in a multi-story building in Saudi Arabia's Madinah region. This study's goal is to determine the most effective and efficient slab system performance in a seismic zone. The ETABS V20.3 program was used in this work to model and assess the seismic response of three different types of slab systems: flat, solid, and hollow blocks slab types. Many earthquake aspects, including story displacement, base shear, story drifts, column forces, and bending moments, are estimated for each system. The study examines and assesses each system's seismic response, and the conclusions are given and discussed. According to the findings, the choice of slab system has a considerable impact on the seismic reaction of the building. The hollow block system has the least base shear value and bending moments, while the flat slab system has the greatest. The values in the solid slab system are in the middle. In terms of story displacement and column forces, the study additionally indicates that the hollow block type system performs effectively in terms of story drifts, however, the solid slab system outperforms the others. The study's findings can assist designers and engineers to determine the best slab system for multistory buildings in seismic-prone areas by providing important insight and suggestions.

Cost-effective methods for flexural strengthening of one-way RC precast flat slab bridges in South Carolina

In South Carolina, there are one-way precast RC flat slab bridges that were constructed in the 1950 s for H-10 and H-15 design trucks (lower than the current design standards) and have deteriorated over time. To ensure public safety and continued usage, strengthening the bridges is imperative. Various methods exist for flexural strengthening, including application of UHPC from above and strengthening from below with FRP, steel plates, and external prestressing. However, these methods may compromise the ductile behavior of the slabs and they are also challenging, labor-intensive, and expensive to apply. The innovation of this paper lies in investigating the methods for strengthening from above that have the potential to improve both the flexural strength and ductility of slabs, while offering advantages in terms of ease of implementation and cost-effectiveness compared to existing methods. Five slabs obtained from decommissioned bridges in South Carolina were tested under monotonic loading to failure: one reference slab; one slab strengthened with steel channel sections from above; one slab strengthened with steel plate sections from above, and two slabs connected at the joint by near surface mounted steel rebars for strengthening. Strengthening the slabs with steel channel sections from above effectively improved the flexural strength and ductility of the slabs while being more economical and easier to implement than other methods of strengthening. Following strengthening, some slabs may require overlays to cover the steel sections and ensure that bridge traffic may go on them. Even after accounting for reduction in strength gain due to the deadload of the overlay, a positive net strength gain in measured peak moment was observed in the strengthened slabs. The moment capacities of the slabs, as determined through design calculations following the ACI 318–19 code, exhibit a good agreement with the measured peak moment observed in experimental tests, thus validating their reliability as a dependable alternative to solely relying on experimental tests.

Effect of column size on punching behavior of flat slabs with square columns: Numerical investigation

This study investigates the punching behavior of slabs supported by square columns of various sizes at different effective slab depths. Within the research context, a finite element model of the slab-column connections is developed using ABAQUS and calibrated based on 15 test results from the literature. Subsequently, 84 slabs with square columns are simulated, and the effect of column size is assessed in terms of load-rotation behavior, shear stress distribution, cracking patterns, punching capacity, and nominal ultimate shear stress. The findings indicate that all slabs undergo brittle punching failure due to the damage near the column corner, which occurs before the ultimate shear stress is fully reached around the column perimeter. The shear stress of the slab along the column perimeter concentrates at the column corner, with this concentration being more pronounced in slabs supported by large square columns. Moreover, as the column size increases, the punching capacity consistently rises while the nominal ultimate shear stress initially decreases, with the decline of the nominal ultimate shear stress being more significant in thinner slabs. The punching capacity predicted by the finite element analysis is compared to the values derived from ACI 318-19, EC2, MC2010, and CSCT models. The findings suggest that these formulas do not adequately capture the influence of column size on punching capacity, prompting the proposal of a new formula that refines the consideration of column size effects.

Finite Element Analyses of Cast-in-situ RC Flat Slab with an Equivalent Frame for Horizontal Loads

In structural construction practice, the use of reinforced concrete slabs is extremely common due to their structural and economic advantages. An important issue is the study of structural behavior given to horizontal effects. The significance of this is centered not only on the scales caused by wind and construction loads, which are considered to be “normal” i.e., the quasi-static, which is essentially one-way monotonically increasing but also the most researched seismic, i.e., cyclically varying, direction and magnitude effects. The most widespread methods for sizing flat plate slabs to unidirectional, quasi-static horizontal loads are the so-called Equivalent Frame Method and the Effective Beam Width Method. In addition to analytical and basically linear numerical theoretical methods, several laboratory experiments have been performed and published. In this paper, we investigate the behavior of column-supported flat plate slabs against unidirectional, monotonically increasing horizontal loads using an advanced nonlinear numerical modeling method. Numerical models constructed with different geometric dimensions were created with ATENA 3D three-dimensional nonlinear finite element software. In the numerical studies, in addition to the vertical loads in the global sense, the horizontal loads were also taken into account. In our studies, we analyzed the global behavior of the structure, crack propagation, and internal stresses. The results were illustrated on force - displacement diagrams and compared with the results of the laboratory experiments used, thus showing the accuracy and limitations of the numerical modeling procedure. The numerical results were also compared with the results determined on the basis of the equivalent framework models.

Giant enhancement of second harmonic generation from monolayer 2D materials placed on photonic moiré superlattice

Abstract We numerically investigate second harmonic generation (SHG) from a monolayer of 2D-material placed on photonic moiré superlattice fabricated by dielectric materials. The greatly enhanced local field at the resonance modes of moiré superlattice can dramatically boost the SHG response in 2D materials. Considering a typical 2D-material MoS2 monolayer placed on a photonic moiré superlattice of a twist angle 9.43°, the maximum SHG conversion efficiency reaches up to 10−1 at a relatively low intensity of fundamental light 1 kW/cm2, which is around 14 orders of magnitude larger than that from the monolayer placed on a flat dielectric slab without moiré superlattices. The SHG conversion efficiency from the monolayer can be further enhanced with the decrease of the twist angles of moiré superlattice due to the even more confinement of local field. The flat bands in the moiré superlattices formed by the small twist angles can particularly ensure the efficiency even under wide-angle illuminations. The results indicate that photonic moiré superlattice which can tightly confine light is a promising platform for efficient nonlinear optics.

Limited flexural control of fold-thrust belts on the Jurassic Sichuan Basin, South China

The northern part of the Jurassic Sichuan Basin has long been thought of as a foreland basin in relation to the post-collisional compression along the northern margin of the Yangtze block. However, the exact coupling mechanism between mountain building and basin formation remains unclear. Here, we integrate stratigraphic correlation, basin subsidence analysis and flexural simulation to quantitatively assess the extent to which the fold-thrust belts have controlled basin subsidence. Flexural backstripping of the stratigraphic record, spanning from 201 to 149 Ma, along two cross sections that are perpendicular to the Micangshan fold-thrust belt and the Dabashan fold-thrust belt, respectively, reveals a limited flexural control of mountain loading on basin subsidence. Owing to the short-wavelength nature of plate flexure, the basin-adjacent thrust belts exerted dominant control on basin subsidence only along its margin, with the width of the foredeeps not exceeding ca. 120 km, failing to drive subsidence in the forebulge and backbulge regions. Flexural modeling results suggest that crustal thickening was relatively weak during the Early to Middle Jurassic. This was followed by a more rapid and intense phase of crustal growth in the Late Jurassic, possibly extending into the earliest Early Cretaceous. Compared to the Micangshan region, the Dabashan region has experienced more intense compression during the Late Jurassic. Additionally, our results reveal spatial variations in plate rigidity along the northern margin of the Yangtze block, with greater plate stiffness in the Dabashan region. The presence of residual subsidence, an anomalous long-wavelength subsidence component corrected for both basin-adjacent thrust loading and associated sediment loading, highlights the necessity for an additional driving mechanism for basin subsidence. This residual subsidence was likely dynamic subsidence induced by the flat subduction of the Paleo-Pacific plate (the Izanagi plate) beneath East Asia as the flat slab progressively migrated inland.

Effects of Tire Crumb Rubber and Steel Fiber on Punching Shear Behavior of Two-way Alkali-activated Concrete Flat Slabs

As a result of the rapid increase in the demand for transportation vehicles recently, the accumulation of waste tires causes environmental problems. One of the methods that can contribute to the reduction of this environmental problem is the recycling of waste tires as a construction material in aggregate form. This research investigated the impacts of waste tire crumb rubber with/out steel fiber (SF) on the two-way punching-shear behavior alkali-activated concrete (AAC) flat slabs and performed center point load tests. In the study, one-type of SF and two kinds of scrap tire waste i.e., crumb rubber (CR) and tire particles, were used on the producing of rubberized AAC slabs obtained by 100% as binder made of ground-granulated blast furnace slag (GGBFS). Also, while both fine crumb rubber (FCR) and coarse crumb rubber (CCR) were used together in the AAC slabs, tire crumb rubber (TCR) was used alone at the same proportion. Additionally, the fine aggregate was substituted with 10% and 15% FCR and CCR, and coarse aggregate was substituted with TCR in the same proportions. Additionally, AAC slabs with recycled tire rubber (RTR) were produced as fibrous and non-fibrous using 1% by volume hook-end SF. In total, nine AAC slabs with sizes of 50 x 50 x 6 cm3 were manufactured for the study. Experimental data showed that the inclusion of RTR only slightly reduced the punching shear strength of AAC slabs and the punching shear strength of the slabs increased when SF was added to the mixtures containing RTR.

Design Philosophy and Seismic Analysis of a Multi-Storey Building (B+G+10) with Flat Slabs in Seismic Zone II Using ETABS and SAFE Software

This journal paper presents the design philosophy and seismic analysis of a multi-storey building (B+G+10) with flat slabs located in Seismic Zone II. With the growing population and limited resources, vertical expansion has become a necessity. The economy's development has attracted foreign companies and innovative entrepreneurs, requiring the construction of high- end, safe workplaces. High-rise structures face challenges from wind and seismic loads, making proper design and analysis crucial for safety. The design philosophy emphasizes the use of reinforced concrete due to its versatility, durability, and fire resistance. Reinforced concrete, a composite material of concrete and steel reinforcement, ensures strain compatibility and load sharing between the materials. The paper discusses various design loads, including dead loads, live loads, wind loads, and earthquake (seismic) loads. Dead loads encompass the self-weight and permanent attachments to the structure, while live loads consider dynamic factors due to occupancy. Wind loads are assessed based on the local wind conditions, and earthquake loads are determined using seismic codes. Design principles for foundations, columns, and footings are addressed, with a focus on ensuring structural stability, safety, and uniform settlement. The depth of the foundation is calculated using Rankine's formula, considering soil properties. Column design is crucial, with short and long column classifications, and minimum eccentricity requirements are detailed. The seismic analysis of the building involves the use of ETABS and SAFE software, which enable engineers to model the structure and assess its response to seismic forces. The combination of a sound design philosophy and comprehensive seismic analysis tools ensures the building's ability to withstand various loads, thereby contributing to safety and sustainability.

Are Volatiles From Subducted Ridges on the Pampean Flat Slab Fracking the Crust? Evidence From an Enhanced Seismicity Catalog

AbstractSeamounts and ridges are often invoked to explain subduction‐related phenomena such as flat slab generation, but the extent of their involvement remains controversial. An analysis of seismicity in the region of the Pampean flat slab through an application of an automated catalog generation algorithm resulted in 35,924 well constrained local earthquake hypocenters and a total of 12,172 focal mechanisms. Several new features related to the subduction of the Juan Fernandez Ridge (JFR) were discovered, including (a) a series of parallel lineaments of seismicity in the subducted Nazca plate separated by about 50 km and trending about 20°, and (b) a strong spatial correlation between these deeper (>80 km depth) regions of intense seismicity and concentrations of activity in the crust almost directly above it. Focal mechanisms of the deeper events are almost exclusively (∼81%) normal, while those in the crust are predominantly (∼70%) reverse. The deeper lineaments mirror the orientation and spacing of several seamount chains seen on the Nazca plate, suggesting that these patterns are caused by the same types of features at depth. This would imply that relatively minor features persist as slab anomalies long after they are subducted. The correlation of the deeper seismicity that defines these features with seismicity in the mid to lower crust suggests a genetic relation between the two. We postulate that volatiles from the subducted ridges percolate into the South American crust and induce seismicity essentially by fracking it.

ANALYSIS AND DESIGN OF BUILDING (B+G+10) WITH FLAT SLABS IN ZONE ‘II’ USING ETABS AND SAFE SOFTWARE

Structural Engineering is a Branch of civil engineering which deals in the determination of behaviour of structures in order to predict the responses of real structures like bridges, Buildings, etc. under the improvement of expected loading and external environment during the service life of the structure. Structural Engineers these days are up against the challenging task of striving for the most efficient and most economical design with accuracy in solution while guaranteeing the final design of a building is serviceable for its design lifetime. In reality it’s very difficult to predict with certainty how much damage a building will experience for a given level of ground motion, because there are number of factors that affect the behaviour of the structural systems. The objective is to emphasize on structural behaviour of a commercial building (basement + ground+10 stories) installed with flat slabs for Bangalore (Zone 2) pertaining to medium soil. The building model is designed and analysed using ETABS (Extended Three dimensional analysis of Building System) and SAFE. ETABS is the ultimate integrated software package for the structural analysis and design of buildings. SAFE is the ultimate tool for designing concrete floor and foundation systems. The lateral loads induced from wind and earthquakes in the design and analysis of building is considered. The dead loads are calculated as per IS 875(part 1)-1987, live load is taken as per IS 875(part 2)-1987, earthquake load has been taken as per IS 1893-2002(part 1) and wind load has been taken from IS 875 (part 3)1987. The manual calculations for the design of structural members were compared with the software results which were found to be satisfactory. All the design and detailing procedures for structural members were carried out as per the guidelines of Bureau of Indian Standard code books.