ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING)
Year:2012 | Volume:13 | Issue:2|Papers Count:10

The study on steel fiber in concrete had shown considerable improvement in the mechanical properties of recycled aggregate concrete. There were total of 16 batches of concrete mixes M20 and M30 with 0.0%, 0.5%, 1.0% and 1.5% volume of the steel fibers. Water cement ratio of 0.54 and 0.42 for the above two grades of concrete have been used with aspect ratios of 40 and 60. Each batch of concrete has 12 specimens of which 3 cubes, 3 prisms and 6 are cylinders. A total of 192 specimens have been cast for the present experimental program. The overall compressive strength increases 3% and 2% for aspect ratio 40 and 60 respectively. For flexural strength it increases 6% and 2%. In splitting tensile strength increases 8% and 1%. Similarly modulus of elasticity increases from 2% to 1% for both the aspect ratios at 28 days respectively. There is a significant improvement in the properties of concrete when recycled aggregate is used.

An experimentally obtained pushover curves of a. 1/4 size RC frame models with and without infill wall and steel bracing have been used to calibrate the non-linear analytical model of the frame. The pushover testing has been carried out on three non-ductile frame models namely bare frame (BF), infilled frame (INF) and a steel braced (SBF) frame under quasi-static condition. The non-linear analytical model is further extending for the seismic evaluation and retrofitting of a 4-storied 2D frames using infill wall and steel bracing. In this context; firstly a 4-storied 2D RC frame structure has been analyzed and designed using different versions of IS: 456 and IS: 1893. Re-evaluation of these frames has been carried out to with masonry infill and steel bracing as retrofitting scheme using pushover analysis. The different pushover parameters of the frames before and after retrofitting have been compared.

An investigation on the seismic performance of panel structures with permanent shuttering system is the subject of this article. Three building models with similar plan and different heights are taken into consideration. The nonlinear behavior of these structures are studied by PERFORM 3D software and its multi-layer shell finite elements with fiber sections.Carrying out the analysis, the performance level of each model is determined. According to the obtained results, it is concluded that the performance level of the structures which are designed based on the common codes is higher than their pre assumption, i.e. life safety.

Masonry construction is the most popular and suitable for housing purposes in almost all developing countries. Base isolation in the form of pure friction is the simplest (P-F) among all isolation so far developed which can easily applied to low cost brick masonry buildings. The effect of the earthquake ground motion on the behaviour of isolation system is investigated analytically by using a synthetic accelerogram that is compatible with the design spectrum of IS 1893 (Part 1): 2002 corresponding to the level of maximum considered earthquake in the most severe seismic zone (PGA=0.36g). It is observed that, maximum reduction in spectral acceleration occurs with decrease in coefficient of friction at the cost of increased base sliding displacement. But for structures with Tn<0.2 sec maximum sliding displacement is 50mm for coefficient of friction 0.1. As most of masonry buildings are stiff structures with time period less than 0.2 second the sliding displacement are within plinth projection of 75. Hence P-F isolation is one of the best alternatives for reducing earthquake energy transmission to super structure during strong earthquake leading to lesser damages in masonry buildings.

In this work four algorithms are presented for the integration of equations governing the behavior of von Mises material in plastic limit. Two of them are single-step and the others are double-step algorithms. Single-step algorithms are straight forward extension of backward Euler method or midpoint rule while double-step algorithms are a combination of two. In past similar algorithms were proposed for special cases of isotropic / kinematic hardening; however the algorithms presented in this work are applicable to general isotropic/kinematic hardening laws. Theoretical as well as numerical aspects are presented for all integration schemes and elaborated for double-step algorithms which are less explored in the literature. A comparison is made between the presented algorithms and the classical backward Euler method.

The present work focuses on comparing the performance of precast and monolithic beam-column joints subjected to cyclic loading. Experiments were conducted on 1/3 scale models of two types of precast beam-column connections and a monolithic connection. The precast connections considered are the beam-column connections in which beam is connected to column with corbel using (i) J-bolt and (ii) cleat angle. The specimens were subjected to reverse cyclic loading. The experimental results of the precast specimens were compared with those of the monolithic connection. Axial load was applied to the column using 400kN capacity actuator. The cyclic loading is applied in the beam using another two actuators, one for positive load cycle and the other for the negative load cycle. The hysteresis behaviour, load carrying capacity, energy dissipation capacity and ductility factor were measured and the performance for the precast and monolithic beam-column connections were compared.

Steel sections with concrete infill are being increasingly used as structural members, since filling the steel section with concrete increases both its strength and ductility without increasing the section size. However, the limitations imposed by certain drawbacks of cement concrete are not alleviated or moderated by the encasing steel tube, like its high shrinkage, creep, brittleness, reactivity and low tensile strength, may be a hindrance to the rapid and diversified application of concrete filled steel tubes in line with current emphasis on ductility-based seismic design. In this context, studies are presently being conducted on filled steel composite members, employing lighter, more ductile, high tensile strength and inert polymer-based fill materials for the steel tube. In the present paper, experimental results of concrete-filled steel columns and polymer modified concrete filled steel columns under axial load combined with lateral cyclic loading are reported. Findings of these studies relating to the hysteresis response of filled steel composite columns subjected to axial compression combined with lateral cyclic load highlight the significant increase in ductility and energy absorption capacity of polymer modified concrete-filled steel columns.

In this paper, a new canonical form is introduced for efficient analysis of structures with special geometric properties. Using the properties of this matrix, the number of operations needed for the matrix inversion is considerably reduced employing the decomposition of the block stiffness matrices. The condition for applicability of the presented method is also discussed. For the previously developed canonical forms, the Kronecker products and the corresponding theorems could be used for certain class of repeated structures. Here this class is extended to the stiffness matrices having more general block tri-diagonal form where the diagonal blocks are not necessarily identical, requiring a different treatment. Two examples of finite element models are analyzed to illustrate the efficiency of the presented method.

This paper reports the results of the investigation done on bricks made using bottom ash and fly ash. Bricks were made with various proportions of bottom ash, fly ash and cement. Tests for workability, density, strength, water absorption and ultrasonic pulse velocity (UPV) were conducted. Results show that the compressive strength ranged from 5.5 MPa to 11.68 MPa, maximum water absorption was 15.7% and the UPV ranging from 2260.2 m/s to 2916.1 m/s. The strength of bricks increases with the increase in fly ash; water absorption, and UPV with the increase in fly ash. It is concluded that bricks of good quality can be made using bottom ash and fly ash whereby contributing to sustainable development.

During January - December 2009 more than 219 accelerograph records were recovered from permanent Iran strong motion stations operated by the Building and Housing Research Center. Accelerograms were recovered from ISMN triggered by 159 earthquakes in the magnitude 2.6 to 5.5 range. 21 Of these recording are related to the 17 October 2009 South of Tehran earthquake.Peak ground acceleration was recorded in Bandar Abbas station about 478 cm/s/s on November 3, 2009 earthquake.