Asian journal of civil engineering
Volume:16 Issue: 8, Dec 2015

In this paper, a numerical investigation has been carried out in order to compare the seismic behavior of an existing non-ductile reinforced concrete (RC) structure under different retrofitting schemes (RC-Jacketing, Steel-Bracing and Steel-cage technique) and the same structure designed according to the Algerian seismic code, RPA 2003, in order to establish the most effective and economic retrofit solution. The construction details for the existing building are typical of constructions prior to the seismic guidelines of 1980.The frame structure is evaluated using both a nonlinear static (push-over) analysis to estimate the inelastic strength and deformation capacities and nonlinear dynamic time-history analyses under a set of different ground motions for comparison purposes. The results indicate that retrofitting with RC-Jacketing yields good performance in terms of ductility resistance capacities, the Steel-Bracing system resistance is increased but may collapse for great PGA of ground motions., and the Steel-cage system has a large resistance but low ductility compared to the other retrofitting techniques.

The aim of the research work is to present the results of experimental and analytical studies concerning the cyclic behaviour of reinforced concrete (RC) beams retrofitted with externally bonded Slurry Infiltrated Fibrous Concrete (SIFCON). This study presents a method for retrofitting of reinforced concrete beams to enhance the actual load carrying capacity using High Performance Fibre Reinforced Cementitious Composites (HPFRCCs) laminates SIFCON and which are directly bonded to the tension face at the soffit of the beam by epoxy adhesives and are tested under compression cyclic loading. A total of four beams of size 125 mm width × 250 mm depth × 3200 mm length with effective span of 3000 mm are cast and tested in the laboratory. The laminates of size 125 mm width × 25 mm depth × 2950 mm length are bonded in between the beam supports. Two beams were retrofitted with SIFCON laminates (RBSF1 and RBSF2) and remaining two beams were tested under compression cyclic loading (CB1 and CB2) as a base line specimen. Cyclic responses of all the beams were evaluated in terms of strength, stiffness, ductility ratio, energy absorption capacity factor, compositeness between laminate and concrete, and the associated failure modes. Comparison was made between the numerical (ANSYS) with the experimental results. The results show that the strengthened beams exhibit increased flexural strength, enhanced flexural stiffness, and composite action until failure.

The objective of the present investigation was to evaluate RHA and MK as supplementary cementitious materials (in both binary and ternary systems) in terms of harden properties in blended cement SCC and to identify the optimal level of replacement of ordinary Portland cement (OPC) with RHA, MK, or RHA+MK. The blended cements were prepared by replacing OPC with RHA, MK, or RHA+MK (5–40%) in dry conditions. In addition to that the interrelationship between harden properties such as compressive strength and ultrasonic pulse velocity was discussed.

The aim of this paper is determining the probability of seismic vulnerability of two building, 8 and 5 storied, reinforced concrete residential building as examples of existing buildings in high risk area, in Tabriz. These structures have been modeled in 3D frame in SAP2000 software [17] and excitation with selected twenty ground motion records. Each record have 15 synthetic records. As a result, a total of 300 records were entered into SAP2000. We evaluate the ISDR at each storey and retain the maximum value to give an overall idea of the building damage level. By comparing structures response together and with damage states, it can be concluded that the structures reach to initially predicted performance. The study presented in this article summarizes the vulnerability analysis for the case studies of Tabriz in East Azerbaijan (the north-west of Iran). These buildings are of regular shape with 8 and 5 numbers of stories. The analysis consider seven damage states, from none to complete collapse, complying with Rossetto and Elnashai [15] classification.

Utilization of industrial waste products in concrete is gaining importance all around the world due to the rise of environmental consciousness. Rubber from worn out tyres is one such waste material thought of by the researchers. Recycled rubber aggregates produce more elastic concrete, which has higher resistance to specific loads (impact loads, vibration and cyclic loads) compared to conventional concrete. Therefore, in this paper, the effect of crumb rubber on properties of Ordinary Portland Cement (OPC) Concrete and Ternary Blended Cement (TBC) Concrete of M40 grade are investigated with fly ash and silica fume as powders along with cement. TBC concrete has shown high energy absorption and higher strengths compared to OPC concrete.

Cold-formed steel built-up sections are commonly used as compression elements to carry larger loads and longer spans when a single individual section is insufficient. For such cases lapping of two sections at the interior support is done to maintain the continuity of the beams. Connections are an important aspect of such structures since structural behavior, and hence economy, is dictated to a large extent by the behavior of the connections. There are numerous types of fastenings between cold formed steel components. However, where holes are punched during forming, bolts are by far the most common type of fastener used in practice. This paper describes about the structural behaviors like buckling modes, maximum load carrying capacity and other possible modes of failure of the whole members under static loading at the lapped area. Two separate beams are taken and lapped with bolts to form a single continuous beam. The two lapped cross sectional C-shaped sections are made with varying cross sectional area. Totally three beams with lapping distance varied between them are tested. Finally the experimental results are compared with numerical analysis using ANSYS.

Tall building designs are changing with the emerging demand of various architectural features and efficient design based on structural geometry. With the growing demand, tall building structures are paving way towards challenging aspects of design with unconventional expressions. More slender structures are proposed with economic and structurally efficient design. This necessitates the study of wind loading effect on various geometrical shapes and also the interference behaviour due to surrounding buildings and their spacing in the neighbourhood. Sufficient availability of pressure and force coefficients for symmetric and regular buildings are provided in various international codes, but they lack the study of interference effect and unsymmetrical building plans. The present research work is a numerical study of wind interference effect and its optimization caused by the change of inter-spacing of interfering buildings and also the varying wind angle of attack on a pentagonal plan shaped building which serves as principle building.

Currently walls in the masonry structures are usually connected to the walls perpendicular to them, hence, they are as flanges for the main walls. The existence of these walls as flanges causes increasing the structural stiffness and finally improving the lateral bearing capacity of the structure. It is obvious that this improvement are obtained when the proper connection between the walls and their compounds can be assured. One of the most weaknesses of the flanged unreinforced masonry wall is the less bond between the compounds and the low tension capacity of the materials that result in the decreased capacity and ductility of the whole. In the recent years, FRP strengthening of unreinforced masonry wall has been identified as an effective technique to increase the resistance and ductility of the system. So, considering the nonlinear behavior of the materials and by means of finite element analysis, this study evaluated the seismic behavior of the FRP strengthened flanged unreinforced masonry walls. In strengthening scheme, two polymer fibers of glass and carbon with different configurations were used. To validate the considered modeling hypothesis and the FE meshing, the results of the nonlinear analysis were compared along with the experimental results. The results of the parametric analysis showed that stiffness and strength of the FRP is effective in increasing the capacity and ductility of the flanged unreinforced masonry walls; so that it caused 185% increase of the capacity and 60% increase of ductility in flanged masonry wall compared with the rectangular one. This increase was 22% in comparison with the ordinary unreinforced masonry walls. Although using FRP sheets as X or L form increases the stiffness and strength of the wall, it has no more effect on the ductility.

A micro level study of seismic risk assessment is proposed considering spectrum based on attenuation relation in Indian context. A seismic loss model using regional ground motion attenuation relation which allows specifying hazard on micro-seismic level in terms of source-site parameters of the scenario earthquake is used. The advantage of using attenuation relation in defining hazard scenario is an improvement over the code defined response spectra which assumes the ground motion response as elastic curve which is unrealistic. The damage probability of the buildings is calculated from the performance point obtained by using capacity spectrum approach. The loss model as per HAZUS is adopted for the risk estimation. The proposed methodology is used to estimate the seismic loss of an institutional campus of India as a case study and the estimated direct economic loss is found to be 3,70,70,067 (INR). The methodology can also be used as an effective tool for disaster preparedness.

It is important to durable of structure and reduce CO2 emission through the greater use of substitute for Cement. The processing of geopolymer using fly ash, GGBS and activator solution. After making the concrete mixer of AS and aggregates, such as cube and cylinders. It is cured and tested for compressive strength. The durability ofgeopolymer concrete is tested by immersion in chemicals that are HCl and MgSO4. Alumina-Silicate is the binder in GPC, which react with acid and salt. The different grade of concrete is used as “M20, M30, M40, M50 and M60”. These specimens are immersed separately in 5% of magnesium sulphate and 5% of hydrochloric acid with 90 days. The change of weight and strength over a 90 days for acid and salt reaction on geopolymer concrete are periodically monitoring surface deterioration and depth. The test results indicate that the geopolymer concrete has an excellent resistance to acid and sulphate attack when compared to conventional concrete.