"Asian Journal of Civil Engineering"

Chandel, Varun Singh;Sreevalli, I. Yamini

doi: 10.1007/s42107-018-0083-7pmid: N/A

Abstract Masonry infill is generally treated as non-structural element and is usually neglected during the design in spite of its strength and stiffness contribution to the lateral load resistance. The interaction of masonry infill with RC frame structures is complex and depends on various parameters such as strength of masonry infill, mortar, concrete, aspect ratio of the infill, openings in infill, and distribution of infill in plan and elevation. Though the number of bays and storeys affect the interaction of the infill and RC frame, earlier experimental research predominantly consisted of a one-storey one-bay frame. Limited research is available due to the difficulties in experimentation, cost and testing facility. Open ground storey (pilotis) structures are recommended to be avoided in high seismic zones because of the formation of soft storey mechanism and sudden failure of the ground storey. This numerical study aims at understanding the behaviour of fully infilled RC masonry frame in comparison with OGS frame. The parameters include aspect ratio (height to length ratio), number of bays and number of storeys. Interestingly it has been observed from the results that the failure is at the ground storey irrespective of infilled ground storey or OGS.

Ez-zaki, Hassan;Diouri, Abdeljebbar

doi: 10.1007/s42107-018-0084-6pmid: N/A

Abstract This paper describes the evolution of the microstructure and physicomechanical properties of mortar and paste samples based on marine wastes. Dredged sediments were characterized, assessed according to the European environmental regulations, and treated at high temperatures with oyster shell powders. Pastes based on the treated materials are then prepared and characterized. SEM observations showed that the microstructure appears to be extremely dense and homogeneous with the appearance of micro-cracks and voids. In addition, the EDS analysis revealed the presence of hydrated products, anhydrous phases of cement and other compounds of sediments and shell powders. The C–S–H phase was defined by the Ca/Si molar ratio and showed a variety of the amorphous phases in the various pastes. Physical and mechanical properties were investigated.

Lesmana, Yudha;Sugihardjo, Hidajat

doi: 10.1007/s42107-018-0085-5pmid: N/A

Abstract This research presents the vertical characteristics of Modified Circular Perforated-Reinforced Elastomeric Isolators (MC-PREIs) under compression. Research on base isolation was undertaken to derive the lowest horizontal stiffness to obtain the fundamental period of an isolated structure, typically for light structures, such as residential housing. To achieve this purpose, geometric modifications were introduced by reducing the loaded area of the isolators. Prior to observing the horizontal characteristic, the vertical stiffness of MC-PREIs was considered to ensure that the interior modification influences the vertical characteristic of the isolator. Therefore, understanding of vertical characteristics due to interior modification was required. In this study, experimental vertical test results of Perforated-Reinforced Elastomeric Isolators (PREIs) were used to verify three-dimensional (3D) finite element (FE) model analyses of ANSYS. Furthermore, the 3D finite element models were used to undertake a parametric study on three MC-PREI configurations with different geometries. The FE method investigation considered the influence of the geometric modifications on the vertical stiffness and the compression modulus, in addition to strain and stress distribution in the perforated reinforcement and elastomer. The finite element analysis indicated that the greater reduction area in the isolator generated decreases significantly in compression modulus and vertical stiffness in addition to increasing the stress distribution on both rubber and perforated plate under compression.

Madouni, Lylia;Ouali, Mohand Ould;Hannachi, Naceur-Eddine

doi: 10.1007/s42107-018-0086-4pmid: N/A

Abstract The present work presents an accurate finite element model for conducting a nonlinear analysis of hybrid coupled shear wall structures. The FE model built in the commercial code Abaqus describes the response of in-plane reinforced concrete (RC) shear walls connected with steel coupling beams. The material nonlinearities of concrete, reinforcement and beam steel were considered. An experimental test on simple coupling beam specimens was chosen to investigate limitations of the previous researches on steel coupling beams, particularly with regard to load transfer to structural walls. It is found that the FE model predicts correctly the experimental results. Indeed, the load–displacement behaviour of the overall structure and the corresponding failure modes are correctly described. In the second step, a parametric study was conducted to examine the influence of the embedment length, steel beam profile and concrete strength on the behaviour of the connection. It is observed that increasing these parameters increases the strength in all cases, whereas the displacement stabilizes when the embedment length is greater than half the wall width and concrete strength exceeds 30 MPa. Moreover, the distributions of the compressive stresses at the steel profile-concrete contact surfaces in different cases show an average estimation of the length in the compression zone above and below the embedded steel section.

Alighardashi, Abolghasem;Mehrani, Mohammad Javad;Fakhravar, Niloufar;Ramezanianpour, Amir Mohammad

doi: 10.1007/s42107-018-0087-3pmid: N/A

Abstract In this study, the physical and mechanical properties of pervious concrete (PC) containing nano-silica (NS) was carried out. Mix design based on the Taguchi method in three levels and four factors (water to cement ratio, aggregate to cement ratio, the percentage of nano-silica, and percentage of fine aggregate (FA)) were examined. Concrete properties such as compressive strength, density (D), permeability (P), and porosity were evaluated. Among nine mix designs, the optimum one according to Taguchi optimization results was found from experimental results: (W/C) = 0.26, (A/C) = 5, 6% (NS) and 20% (FA). The corresponding mechanical and physical properties had a compressive strength of 3.6 (MPa), permeability of 1.06 (cm/s), void ratio of 19.7 (%), and density of 879 (kg/m3). Adding NS (up to 6% of cement weight) and FA (up to 20% of aggregates weight) had an important effect on almost all tests especially on CS, and there was no impressive influence related to another factor (W/C, A/C) in all tests. It is noticeable that the influence of adding NS to the mix design on CS was higher than adding FA.

Afzali-Naniz, Oveys;Mazloom, Moosa

doi: 10.1007/s42107-018-0088-2pmid: N/A

Abstract The effects of different replacement levels of micro-silica (MS), colloidal nano-silica (CS) and also the combined addition of MS and CS on the behavior of self-compacting lightweight concrete (SCLC) were studied using the general full factorial design method. Three factors, including water to binder ratio (w/b) with two levels of 0.35 and 0.45, CS with four replacement levels of 0, 1, 3 and 5%, and MS with two replacement levels of 0% and 10% were chosen and three tests were conducted for each response. The modulus of elasticity, compressive strength and water absorption were selected as the responses at the age of 28 days. Also, using multiple regression analysis, acceptable prediction regression models were derived. The analysis of variance (ANOVA) showed that the effects of all three factors on fresh and hardened properties of SCLCs were significant. The results displayed that the mentioned properties for the SCLC specimens containing MS or CS improved, but the best performance was obtained in ternary mixes which were created by adding both MS and CS simultaneously. The optimal condition for having the best result of SCLC was obtained when the amounts of MS and CS were 10% and 3%, respectively.

Gouasmi, M. T.;Benosman, A. S.;Taïbi, H.

doi: 10.1007/s42107-018-0089-1pmid: N/A

Abstract The present work aims to highlight the use of polyethylene terephthalate (PET) plastic waste for the conception of a new PET-siliceous sand composite material (WPLA) to be used, after heat treatment, as a light aggregate in various screed mortars. This composite is intended to be employed as a substitute for conventional aggregate at the rates of 0, 25, 50, 75, and 100% by weight. Reinforcement corrosion, caused by the attack of chloride ions, is the main reason for the deterioration of reinforced concrete structures around the world. To determine the effects of waste PET as a lightweight aggregate (WPLA), five WPLAX composite mortar formulations were immersed into a 5% NaCl solution. The mechanical strength, absorption of water by capillary suction, and chlorine ion penetration into mortars were all studied. Additional information on the microstructure of the materials was also collected. The results obtained indicated a decrease in the compressive strength of WPLAX. Moreover, Fick’s second law made it possible to observe a decrease in the penetration of chlorine ions, ranging from 40 to 90% in WPLAX mortars as the replacement ratio increased. Likewise, it was found that the sorptivity coefficients of WPLAX mortars decreased from 43 to 65% as compared to that of reference mortar. These encouraging results open up new prospects for using these composite materials as protective mortars for reinforced concrete structures. At the same time, it is one way of getting rid of these PET plastic wastes which represent a serious pollution form to the environment and a real threat to human health.

Parate, Kanak N.; Kumar, Ratnesh

doi: 10.1007/s42107-018-0090-8pmid: N/A

Abstract In this study, a simplified empirical model is proposed to estimate the shear strength of reinforced concrete beam–column joint. For development of proposed model, various governing parameters affecting the joint shear strength have been identified and evaluated. The identified parameters, namely, concrete compressive strength, width of beam and column, depth of beam and column, column axial load, longitudinal reinforcement of beam and column, yield strength of reinforcement, and joint shear reinforcement, are considered. The influence of aforementioned parameters is determined from the statistical evaluation of collected 326 experimental results of interior and exterior beam–column joints from the literature. The database consists of specimens with wide range of above-mentioned parameters. Proposed model is suitable for the beam–column joints reinforced with vertical, horizontal and diagonal (X-cross) type of reinforcement. Based on experimental database, the efficacy of proposed model is compared with various joint shear strength models. Comparison shows that proposed model predicts more accurate joint shear strength than other considered models. The proposed model is simple in use and can be used for the design purpose.

Adebakin, I. H.;Gunasekaran, K.;Annadurai, R.

doi: 10.1007/s42107-018-0091-7pmid: N/A

Abstract The focus of this study is on the development of self-compacting lightweight concrete using local waste materials and investigation of its mechanical properties. Discarded fresh coconut shells were crushed mechanically and used as coarse aggregate with fly ash (FA) as partial replacement of Portland cement at 15% and 20% replacement levels by weight. Slump flow, T500, V-funnel, L-box, and wet sieve segregation tests were used to evaluate the self-compactibility of the developed mixes. For comparison purpose, self-compacting conventional concrete was also produced and tested for all the parameters experimentally. For the developed self-compacting concrete mixes, mechanical properties such as compressive, flexural, splitting tensile strengths, and impact resistance were tested and compared with the theoretical values as recommended by the standards and the literature references. Compressive, flexural, and splitting tensile strengths of 21.20 N/mm2, 4.50 N/mm2, and 2.56 N/mm2 with impact energy of 528.61 kN-mm were achieved for 15% FA and 20.10 N/mm2, 4.00 N/mm2, and 2. 52 N/mm2 with impact energy of 467.61 kN-mm achieved for 20% FA, respectively. This shows that the experimental values of all the parameters are high in performance compared to the theoretical values, and hence, coconut shell aggregate blended with fly ash is a promising local technology for structural lightweight concrete usage.

TahamouliRoudsari, M.;Cheraghi, K.;Habibi, M. R.

doi: 10.1007/s42107-018-0092-6pmid: N/A

Abstract Many buildings require reinforcement for various reasons including earthquake damage, change in design regulations and occupancy, adding stories, and lack of proper construction. One of the retrofitting systems that, in addition to increasing the lateral strength, provide the structure with significant ductility is the ADAS yielding damper and is of great interest today. The main objective of this research is to numerically investigate the effects of ADAS plates and columns’ axial loads on the seismic parameters of reinforced concrete (RC) moment resisting frames. Therefore, based on 48 calibrated numerical models, the Pushover analysis was performed and the effects of axial force and number of ADAS plates on the seismic parameters of the frame such as effective stiffness, ultimate strength, energy dissipation, and ductility were investigated. In addition, analytical relationships were presented to determine the ultimate strength and stiffness of the reinforced frame. The results show that the number of ADAS plates should be determined in such a way so that the shear strength of the RC frame is at most about 3 times greater than that of the original concrete frame.