ISSN 0970-0137

Current Issue

February – March 2019 issue, Vol. 45 No. 6

Shape memory alloy based smart link for aircraft wing structure: FE modelling and experiments

##### A.Vasanthanathan, P. Nagaraj, K. Karthick Raja, R. Kumar Arjun and M. Rajakalai

Shape memory alloy based smart link for aircraft wing structure: FE modelling and experiments

##### A.Vasanthanathan, P. Nagaraj, K. Karthick Raja, R. Kumar Arjun and M. Rajakalai

This article emphasizes on the development of Shape Memory Alloy (SMA) based smart link for the flight control system. SMA are the candidate material for the actuation of smart structures due to its Shape Memory Effect (SME). In this paper, Nitinol® is used as an SMA which is of 55% Titanium and 45% Nickel. Nitinol® in spring form, proposed in the present paper actuates the aileron which is a primary flight control system through a smart link system. The aileron facilitates the rolling motion of an aircraft. Due to symmetry, this paper addresses the actuation of aileron in one wing. Both experiments and finite element modelling are carried out. The finite element modelling of a cylindrical portion of SMA was performed so as to numerically exhibit the SME. The finite element simulation of the aileron actuation was performed by incorporating the effect of SMA spring. The finite element analysis reveals that as the temperature exceeds the phase transformation temperature (Tp), the material regain its original shape. The finite element analysis of SME was computed using ANSYS® Mechanical APDL 17.2 environment while the aileron actuation was simulated in ANSYS® 16.0 Rigid Dynamics environment. The SMA spring are actuated by heating to its phase transformation temperature. Analytical calculations are also presented for the detection of current value to be supplied into the SMA spring. Experiments are conducted in a Glass Fabric Reinforced Plastic (GFRP) wing model and the actuation of smart link has been investigated.

Study on geopolymer mortar using hydrogen peroxide as foaming agent

##### N. Anuja, and S. Prabavathy

Study on geopolymer mortar using hydrogen peroxide as foaming agent

##### N. Anuja, and S. Prabavathy

A new arising technology called geopolymer with zero percentage of cement has been developed in order to protect our environment from harmful CO2 emission and further to save energy in the world for future use. Several drawbacks of ordinary portland cement such as low tensile strength, unstable crack propagation and low fracture resistance have been overcome by geopolymer. Further to make geopolymer as a good thermal insulating material with adequate strength, some foaming agents are added to the geopolymer mix. Foaming agents intend to develop pores inside the specimen to make it as lightweight. In this work, hydrogen peroxide is preferred as foaming agent which is added in diluted as well as undiluted form in the range of 0.3-1.8% at an interval of 0.3% so as to find the best specimen which has low density and thermal conductivity with adequate compressive strength. From the result, it was found that the geopolymer mortar cured at 80ºC for 24 hours in hot air oven with 0.9% hydrogen peroxide in diluted form gives the best result with compressive strength and density of 4.641MPa and 1209kg/m3. It also gives low thermal conductivity of 0.141W/mK when compared to normal geopolymer mortar.

Experimental and finite element analysis of tubular conveyor gallery

##### M. Gopinath, and R. Senthil

Experimental and finite element analysis of tubular conveyor gallery

##### M. Gopinath, and R. Senthil

A conveyor system is a continuous system for haulage of the bulk materials. It enables us to haul anything from corn to iron ore in a continuous flow from one end of the plant to the other, feeding and reclaiming material through the different stages of the process. The tubular conveyor galleries consist of a tube, shop fabricated using steel plates forged to the required radius and welded at the longitudinal and circumferential joint section in a staggered pattern. This paper presents details of the finite element analysis (FEA) carried out to understand the behaviour of the tubular conveyer gallery systems subjected to concentrated load due to conveyer supporting system subjected to biaxial bending. Studies carried out to obtain the optimum size of the openings that can be provided for lighting and ventilation without affecting the stability of the structure to withstand dynamic loads are explained. Details of experimental investigations carried out on the scaled down model of the tubular conveyor gallery to compare the results of FEA is also presented in this paper.

Comparative studies between Indian Standard codes IS 802 (part 1/ sec 1):2015 and IS 802 (part 1/ sec 1):1995 used for overhead transmission line t

##### Vikki K. Shah, V.R. Panchal and Bipin B. Shah

Comparative studies between Indian Standard codes IS 802 (part 1/ sec 1):2015 and IS 802 (part 1/ sec 1):1995 used for overhead transmission line t

##### Vikki K. Shah, V.R. Panchal and Bipin B. Shah

Transmission line towers are steel lattice structures and were generally analyzed and designed as per Indian Standards code IS 802 (Part 1):1995. A revised code IS 802 (Part 1/ Sec 1):2015 is introduced recently for transmission line towers with modified load combinations and material input provisions. So far no attempts have been made to compare the previous code with the revised code in terms of design, analysis efficiency and economy. The present study is aimed to compare the loading, axial forces, deflection and weight of the tower using the analysis and design procedure of previous and revised codes. Two transmission line towers of same geometry were analyzed and designed using STAAD.Pro V8i software using provisions of previous and revised codes. The conclusions drawn from the comparison shows that the axial forces at critical points as per IS 802 (Part 1/ Sec 1):2015 design is 25 to 40 %, 15 to 25% and 18 to 30% for 132kV, 400kV and 765 kV respectively less than design based on IS 802 (Part 1/ Sec 1): 1995. The difference in total weight of the tower material as per IS 802-2015 design is 6.24%, 5.92% and 5.72% for 132kV, 400kV and 765 kV respectively lesser in comparison to IS 802:1995 lesser in comparison to IS 802 (Part 1/ Sec 1): 1995 design.

Improved confinement model for reinforced concrete circular bridge columns under static flexural loading

##### Naresh Surepally and S. Suriya Prakash

Improved confinement model for reinforced concrete circular bridge columns under static flexural loading

##### Naresh Surepally and S. Suriya Prakash

This study presents an improved analytical approach for the analysis of Reinforced Concrete (RC) circular bridge columns by proposing a new confinement model under static loading. Three widely used confinement models are examined and improvements are suggested. It is well known that the stress-strain behaviour of confined concrete is completely different from that of plain concrete. The level of confinement depends on amount of transverse reinforcement, amount of longitudinal reinforcement and spacing of rebars and level of axial load. The influence of these parameters on the section and member level behaviour is analysed and an improved model is proposed for the analysis of RC circular bridge columns under flexure. Predictions of the analytical model are compared with the experimental data of columns tested by the author and others from PEER DATABASE over a range of parameters. The comparisons indicate a very good agreement of the predictions of the proposed model with the test data.

Earthquake-response of open ground storey reinforced concrete building retrofitted with and without yield type X shaped metallic elasto-plastic dam

##### C.K. Madheswaran, N. Gopalakrishnan, J. Prakashvel and K. Sathish Kumar

Earthquake-response of open ground storey reinforced concrete building retrofitted with and without yield type X shaped metallic elasto-plastic dam

##### C.K. Madheswaran, N. Gopalakrishnan, J. Prakashvel and K. Sathish Kumar

A three-storey half scale Reinforced Concrete (RC) building frame model, fitted with yielding type X-shaped metallic elasto-plastic damper at the ground floor level, is designed and fabricated to study its seismic response characteristics. Experimental studies are carried out using the 4m × 4m tri-axial shake-table facility to evaluate the seismic response of a retrofitted RC frame building with Open Ground Storey (OGS) structure using yielding type X-shaped metallic elasto-plastic dampers (also called as Added Damping and Stiffness-ADAS elements) and repairing ground storey columns using Geopolymer concrete composites. In general, earthquake loading introduces large displacements in an OGS structure, and under such large displacements, a yielding type elasto-plastic device made of X-shaped metallic dampers is expected to perform better. The supporting steel frame of ADAS element is of chevron type, serially contributing stiffness to the ADAS element. Free vibration tests on RC frame building without and with yielding type X-shaped metallic damper are carried out. The natural frequencies and mode shapes of model without and with yielding type X-shaped metallic elasto-plastic damper are obtained. The reinforced concrete building is subjected to earthquake excitations. Further, seismic responses of the structure with metallic damper are evaluated with different earthquake excitations.

Mechanical behaviour of pre-stressed railway sleepers using geopolymer concrete

##### S. Imran khan, D. Brindha and G. Panneerselvam

Mechanical behaviour of pre-stressed railway sleepers using geopolymer concrete

##### S. Imran khan, D. Brindha and G. Panneerselvam

Geopolymer concrete can be considered as a green building technology which serves as alternatives for cement and fine aggregate by using Alkaline Activator Solutions (AAS) Fly Ash (FA) Granulated Blast Furnace Slag (GGBS) and Copper Slag (CS) in Geopolymer Concrete (GC). The High Strength Geopolymer Concrete (HSGC) M60 grade concrete was designed and used for the casting of Broad Gauge Pre-tensioned Pre-Stressed Concrete (PSC) sleepers as per Indian Railway Standard Specifications. Pre-tensioning wires of standard High Tensile Strength wire (HTS) were used with a pre-tensioning force of 50kN. Compaction was achieved through table vibrators and steam curing was adopted as per the standard manufacturing process of Indian Railways. The cured concrete sleepers were tested in the lab by stimulating the actual load transfer condones in the field called Rail Seat Centre Bottom (RSCB). Moment of Resistance (MR) and Moment of Failure (MF) of the sleeper was determined for either sides of the sleeper for a loading up to 230kN (MR) and 370kN (MF) as per the standard static bending test procedure. The test results proved that the Geopolymer concrete sleeper has high yield load and high ultimate load.

Flexural behaviour of reinforced fly ash and paper sludge ash- based geopolymer concrete beams

##### P. Senthamilselvi, and T. Palanisamy

Flexural behaviour of reinforced fly ash and paper sludge ash- based geopolymer concrete beams

##### P. Senthamilselvi, and T. Palanisamy

The Present study aims at incestications of the flexural behaviour of reinforced Fly Ash (FA) Based Geopolymer Concrete (GPC) and fly ash and Paper Sludge Ash (PSA) based geopolymer concrete beams (FA-PSA-GPC) with 10% replacement of FA by PSA. The beams were made of M35 grade concrete and cured under three curing conditions viz., Ambient Curing (AC), External Exposure Curing (EEC) and Oven Curing (OC) at 60°C. The beams were tested at 28th day by conducting two-point loading flexural test. Performance aspects such as Load Carrying Capacity (LCC), First Crack Load (FCL), load-deflection behaviour, and moment-curvature behaviour of both types of beams were studied. The load-deflection and moment-curvature behaviours of two types of beams observed from the experimental results under different curing conditions were compared and it was concluded that GPC can be produced using PSA with FA.

Comparison of behaviour between rebar and stud shear connectors under monotonic loading

##### B. Saravanakumar, and R. Thenmozhi

Comparison of behaviour between rebar and stud shear connectors under monotonic loading

##### B. Saravanakumar, and R. Thenmozhi

In composite beams, shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. The shear connectors also prevent relative displacement of concrete and steel elements at their interface and ensure composite action of the beam. Presently, the stud is the most widely used shear connector in composite constructions. However, the rebar can be used as a shear connector according to various international codes considering the fact that it can be fabricated to the required shape along with the reinforcement cage in the slab. This paper presents an experimental study of the behaviour of rebar shear connectors embedded in composite beam under monotonic load. Two different (8mm and 10mm) diameter rebar connectors of four different forms such as open link, closed stirrups, circular and rectangular spiral were used as shear connectors. Modified push-out tests were conducted to assess the ultimate strength, elastic stiffness, load-slip characteristics and failure pattern of the rebar shear connectors and the same are compared with conventional stud shear connectors. Rebar shear connector with circular spiral shows higher ultimate strength and superior ductile behaviour compared to conventional stud shear connector.

Parametric study on seismic behaviour of slab-column junctions in flat slab system subjected to punching shear

##### Vijaya Kumar Kandi, Lute Venkat, and G. Papa Rao

The effect of lift thicknesses on thermal stresses in roller compacted concrete (RCC) gravity dam

##### Birhane Gebreyohannes Hagos, I. Siva Parvathi, and T.V. Praveen

The effect of lift thicknesses on thermal stresses in roller compacted concrete (RCC) gravity dam

##### Birhane Gebreyohannes Hagos, I. Siva Parvathi, and T.V. Praveen

A two dimensional thermal stress analysis of a zoned roller compacted concrete gravity dam, viz., Gibe-III RCC gravity dam of 214m high non-overflow section is carried out for predicting non-uniform development of temperature in hydrating concrete with respect to time and space during its construction using finite element method. The influence of the thermal properties and the climatic conditions, and the placement schedule of RCC layers are considered in the analysis. The available laboratory heat of hydration data and the incremental construction process of mass-concrete structure are modeled to produce results that can be used in construction planning and casting schedule of RCC dams. The present study considers three lift layer thicknesses, i.e., 3m, 4m and 6m in the construction of Gibe-III RCC gravity dam, and temperature and thermal stress distribution corresponding to each lift thickness has been computed. The probability of crack occurrence due to the change in the temperature gradients in the core and surface of the dam is also calculated. The study demonstrates that detailed thermal stress analysis should be performed for large RCC gravity dam like Gibe-III in order to minimize and control the occurrences of thermal cracking.

Influence of opening on the behaviour of bamboo reinforced concrete wall panels under two way in-plane action

##### N. Ganesan, P.V. Indira and P.R. Himasree

Influence of opening on the behaviour of bamboo reinforced concrete wall panels under two way in-plane action

##### N. Ganesan, P.V. Indira and P.R. Himasree

The paper presents the influence of opening on the performance of bamboo reinforced concrete wall panels under two way in-plane action. Six prototype bamboo reinforced concrete wall panel specimens were tested for failure under uniformly distributed load that was applied at an eccentricity of one-sixth the thickness of the wall panel. Of the six specimens considered in this study, three were solid wall panels, and the rest three possess opening at its centre. The specimens considered were having a constant slenderness ratio of 25 with varying values of aspect ratios of 1.67, 1.82 and 2 and thinness ratios of 12.50, 13.75 and 15. Area of the opening provided was exactly 25% of the area of the specimen. The study indicates that the ultimate load of wall panels decreases with an increase in aspect ratio regardless of the presence of the opening. Also, ultimate load increases with the increase in thinness ratio.

Flexure of narrow rectangular deep beams with built-in ends

##### Yuwaraj M. Ghugal, and Ajay G. Dahake

Flexure of narrow rectangular deep beams with built-in ends

##### Yuwaraj M. Ghugal, and Ajay G. Dahake

The paper presents the exact analytical solutions for built-in uniform, isotropic deep beams using sinusoidal refined shear deformation theory under transverse bending. The theory is built upon the classical beam theory including sinusoidal function in terms of thickness coordinate to include the shear deformation effects. The kinematics of the theory enforces transverse shear stress to satisfy the shear stress-free conditions on the top and bottom planes of the beam. The shear stress distribution through the thickness is realistic and requires no shear correction factor. Using the principle of virtual work, the equilibrium equations and boundary conditions have been obtained based on kinematics of the theory. To demonstrate the efficacy of the theory, the exact analytical solutions for beams, with narrow rectangular cross sections, subjected to parabolic and cosine loads are obtained to examine the complete flexural response. Results for these specialized loading cases are obtained for the first time and are discussed critically with those of other theories. The solutions obtained can be served as a benchmark for comparison of results by other refined theories.

Study on performance of infilled wall in RC framed structure using basalt fibre in cement mortar

##### P. Jagadeesan and T. Palanisamy

Study on performance of infilled wall in RC framed structure using basalt fibre in cement mortar

##### P. Jagadeesan and T. Palanisamy

Normally, Reinforced Concrete (RC) framed structure is built by combination of structural and non-structural elements that may satisfy the design and architectural purpose. When RC framed structures are subjected to the static lateral loading, infilled wall and RC frame elements does not react together. At this time, infilled wall is subjected only compressive forces and does not support the tensile force. So, failure is happened due to lacking of ductility and poor interaction between frame elements and infilled wall. Therefore, the objective of this study is to improve the ductility and interaction between RC frame elements and infilled wall through suitable method of strengthening of infilled wall. In this research work, the two types of specimens such as infilled RC framed structure and infilled RC framed structure strengthened by reinforced cement mortar using basalt fibre were cast and tested under experimental and analytical investigation. One-fifth scale model of single-bay, two-storey plane RC framed structure were prepared and tested under cyclic loading with the help of 1000 kN capacity loading frame and foundation block. This study focuses the significant parameters such as load-deflection curve, ductility, energy dissipation capacity, initial stiffness and failure mechanism of infilled RC frame and infilled RC frame with basalt fibre in cement mortar. The result proves that basalt fibre reinforced cement mortar improves the strength, stiffness and ductility of infilled RC framed structure and make infilled wall as integral unit in RC framed structure.

Effect of embedment depth of piles on response of three storeyed building frame incorporating non-linear behaviour of soil

##### S.A. Rasal, H.S.Chore, and V.A. Sawant

Effect of embedment depth of piles on response of three storeyed building frame incorporating non-linear behaviour of soil

##### S.A. Rasal, H.S.Chore, and V.A. Sawant

The study deals with mathematical modeling of a typical three storeyed building frame supported by a pile group of four piles (2×2) embedded in soft marine clay, a cohesive type of soil mass, using three dimensional finite element analysis. For the purpose of modeling, the elements such as beams, slabs and columns, of the superstructure frame; and that of the pile foundation such as pile and pile cap are descretized using twenty noded isoparametric continuum elements. The interface between the pile and the soil is idealized using sixteen node isoparametric surface element. The soil elements are modeled using eight nodes, nine nodes and twelve node continuum elements. The present study considers the linear elastic behaviour of the elements of superstructure and substructure (i.e., foundation); and the soil is assumed to behave non-linear. The parametric study is carried out for studying the effect of soil- structure interaction on response of the frame by resorting to the sub-structure approach. The frame is analyzed initially without considering the effect of the foundation (non-interaction analysis) and then, the pile foundation is evaluated independently to obtain the equivalent stiffness; and these values are used in the interaction analysis. The embedment depth ratio is varied to evaluate its effect on the interactive behaviour of frame in the context pile spacing of 2D. The response of the frame included the horizontal displacement at the level of each storey, shear force in beams, axial force in columns along with the bending moments in beams and columns. The effect of the soil- structure interaction is observed to be significant for the configuration of the pile groups.

Effect of structural irregularities on the seismic behavior of reinforced concrete frames

##### E. Siva Naveen, Nimmy Mariam Abraham, and S.D. Anitha Kumari

Effect of structural irregularities on the seismic behavior of reinforced concrete frames

##### E. Siva Naveen, Nimmy Mariam Abraham, and S.D. Anitha Kumari

Seismic response of multi-storey buildings depends on the distribution of mass, stiffness, strength and geometry in both horizontal and vertical planes of the building. The irregular configurations either in plan or in elevation may cause severe damage in structural system during earthquake events. Locations of sudden change in mass, stiffness and geometry in structures are weak points. Structures possess combination of irregularities. The consideration of single irregularity may not result in realistic prediction of seismic response. Hence, for the safe design of irregular buildings, it is significant to study the combined effect of irregularities on the response of buildings to dynamic loads. The present work addresses the effect of mass, stiffness and vertical geometry on the seismic response of frames. Twenty one different cases of irregularities along with their combinations were studied and compared. Linear elastic time history analysis was performed to evaluate the seismic response of these structures analytically and the results obtained were then compared with the numerical results obtained from finite element software. The analytical results were observed to follow the same pattern as that of numerical studies. Of all the different frame configurations with irregularities analysed, the configuration with combination of mass, stiffness and vertical geometric irregularity has displayed maximum response whereas the one with mass irregularity alone had shown higher base shear and overturning moment.

Probabilistic analysis of buildings with tuned mass damper

##### P. Kamatchi, and K. Balaji Rao

Uncertainties in properties and input earthquake excitation can have significant influence on the response reduction of systems with Tuned Mass Damper (TMD). Hence, an effort has been made in this paper towards statistical characterization of tuning parameters and response of structural systems with and without TMD. Uncertainty in mass, stiffness and Peak Ground Acceleration (PGA) are modelled with mean, coefficient of variation and probability distribution functions adopted from literature. Sample size adopted is 5000 and time history analysis are carried out for a ten storey steel building frame(B1) and fifteen storey RC building(B2) with the random mass, stiffness properties and the samples of ground motions with random PGA. From the Cumulative Distribution Function (CDF) of peak responses and response ratios, it is observed that fitting lognormal distribution is found to pass the K-S goodness of fit test for 95% confidence for peak responses of ten storey steel frame. Whereas, fitting both normal and lognormal distribution do not found to pass the goodness of fit K-S test for fifteen storey RC building. Response ratios of peak displacement do not found to pass the goodness of fit K-S test for both normal and lognormal distribution for both the buildings.

Strength and hysteresis behavior of CFDST columns with octagon and polygon steel sections

##### Ebrahim Farajpourbonab, Sunil Kute and Vilas Inamdar

Issue: April – May 2019 issue, Vol. 46 No. 1

Experimental and numerical studies on GGBS based fibrous geopolymer concrete beams

##### K. Nithyapriya and K. Subramanian

Issue: April – May 2019 issue, Vol. 46 No. 1

Experimental and numerical studies on GGBS based fibrous geopolymer concrete beams

##### K. Nithyapriya and K. Subramanian

This paper presents the investigations carried out on Ground Granulated Blast furnace Slags (GGBS) based geopolymer concrete beams with and without glass fibres. The main ingredients considered for the study include constant GGBS, varying proportions of fly ash, silica fume and metakaolin. Beams were tested under four point bending and various responses such as first crack load, ultimate load, deflection corresponding to ultimate load and crack pattern were studied. From the experimental investigations, it was observed that the behaviour of the beams are similar to RC beams. Nonlinear finite element analysis (FE) has been carried out on RC flexural members made up of GGBS with and without considering glass fibres. The non linear properties of concrete and steel are considered for simulation. The widely used concrete damage model available in ABAQUS has been employed to represent the nonlinear behavior of concrete. The integrity of all the elements i.e. concrete and steel has been ensured by applying the appropriate constraint conditions. Static nonlinear analysis has been conducted and the responses such as peak load and the deformations are compared with the corresponding experimental observations. It is observed that the responses obtained from FE analysis are in close agreement with the corresponding experimental values.