Asian journal of civil engineering
Volume:13 Issue: 6, Dec 2012

Meta-heuristic methods provide powerful means to optimize frame structures and hybridizing these methods seems to be unavoidable to improve the properties of the algorithms. This paper provides a new hybrid advanced algorithm by using the abilities of heuristic particle swarm ant colony optimization (HPSACO) and a hybrid big bang–big crunch algorithm (HBB–BC). The advantages of the HPSACO and HBB–BC are combined to improve the performance of the resulted algorithm. In the present approach, there are three main steps as global searching step, local searching step and location controlling step. These steps all together improve the exploration and exploitation abilities of the algorithm. The proposed method is tested on frame structures from the literature. The results of the optimum design obtained by the present study are compared to those of some existing optimization methods to verify the suitability of the new method.

The paper presents the results of a study on the performance of Glass Fibre Reinforced Polymer (GFRP) wrapped high strength concrete columns under uni-axial compression. The columns had slenderness ratios of 8, 16, 24 and 32. Chopped Strand Mat GFRP was used with 3 mm and 5 mm thicknesses. The columns were tested under monotonic axial compressive loading up to failure. The deflections were noted for each load increment. The HSC columns with GFRP wrapping exhibited improved performance in terms of strength and ductility capacity.

In this paper it is shown how Sylvester equation can be utilized in the analysis of frames in order to reduce the order of solution for regular frames. Furthermore, it is shown how efficient this new algorithm is in comparison to the classic solution. By this comparison, it will be shown that this approach can solve the static analysis simply in an easier and more inexpensive way. Due to the reduction in the number of operations in the solution presented, round off errors are naturally reduced.

Man made accidents while handling explosives in fireworks industries cause loss of human lives and infrastructure due to collapse of walls which indicates that no fully safe manufacturing and construction procedures are followed in these industries. Hence, an attempt is made to suggest a cost effective construction by conducting analytical studies on brick masonry with strengthening measures using ANSYS and the results presented. It was observed that, by providing RCC vertical bands at door jambs, the resistance of brick masonry against accidental overloading can be improved considerably so that progressive collapse of the entire structure can be avoided.

Bamboo is a giant grass and not a tree. Bamboo completes its growth within some months and matures at the age of around three years, there is no secondary growth. Moisture content of bamboo varies along its height location and with seasoning period, which affects all physical and mechanical properties. It is one of the important factors in deciding the life of bamboo. This paper presents results of experimental investigations made to evaluate the physical and mechanical properties of the bamboo species Dendrocalamus strictus and its utilization potential as building material may be as whole or in the split form. In the present study moisture content, specific gravity, water absorption, dimensional changes, tensile and compressive strength at different height location are worked out. The moisture content varies along the height for green bamboo or at any time after harvesting. The top portions had consistently lower moisture content than the middle or basal at all stages of seasoning. Specific gravity on oven dry mass basis decreases from top to bottom and is independent of moisture content. Water absorption is inversely proportional while dimensional changes, tensile and compressive strength are directly proportionate to moisture content.

This experimental work has focused on studying the possibility of using the dune sand powder (DSP) as a part mass addition to Portland cement. The incorporation of dune sand powder form substitution to Portland cement yields a new variety of cement compound with physicalmechanical properties superior to those of Portland cement. The results obtained show that the contribution of addition dune sand powder to the cement binding activity resulted primarily from three effects: Physical, physical-chemical and chemical. These effects act simultaneously and in a complementary way on the properties physical-mechanical and deformability of concrete.

This paper presents an experimental investigation on the behaviour of retrofitted beam-column joints subjected to cyclic loading. The beam-column joints were designed for gravity loading. The same joints were retrofitted for seismic loading with four different retrofitting strategies essentially to achieve equal strength of the segment under sagging and hogging bending moments. The results obtained from the experimental investigation gives better understanding of the strengthening and repair methodology of FRP strips, FRP sheets, MS flats and embedded additional reinforcement in RC beam–column joints under cyclic loading. A simple analyticalmodel proposed by Ibarra et al. is shown to be an excellent tool for performance evaluation of the retrofitted beam column joints. The progressive damage in the retrofitted elements can also be well predicted.

Conventional experimental techniques like, quasi-static, effective force and shake-table techniques are generally being adopted to evaluate the seismic response of a civil engineering structure under earthquake loading. Among these techniques, shake-table technique has a merit over the other techniques due the fact that it realistically simulates all the three basic dynamic force parameters namely inertial, damping and elastic forces in the test structure. However this technique needs a sophisticated shake-table driven by servo hydraulic actuators with excellent control electronics. In the absence of such an expensive shake-table, it is possible to simulate the three dynamic force parameters using a static actuator through application of an equivalent pseudo-dynamic force system by computation of inertial forces in the back-ground. Such a hybrid Pseudo-dynamic (PsD) technique needs a specialized algorithm based on an appropriate mathematical model for the off-line time integration and computation of inertial forces such that the dynamic displacements/forces are applied statically through static actuators. Restoring forces offered by the structure are experimentally measured on-line at each time step and reflects the actual in-elastic and energy dissipation characteristics of the tested structure. The paper presents the mathematical formulation of a ‘predictor-corrector’ method using Newmark implicit relations and its implementation in PsD technique for seismic response evaluation of structures. In the proposed method displacement iterations are made in the corrector phase in achieving the implicit displacement which is an improvement over the conventional method where displacement iterations are made to achieve the explicit displacement resulting in lesser accuracy. To experimentally verify this improved PsD technique, the seismic response quantities including base shear, roof displacement and energy dissipation of a model steel frame structure subjected to a simulated earthquake predicted using PsD technique were calibrated with seismic responses evaluated using standard shake-table technique. The paper also presents the causes for the deviation in the predicted seismic responses using PsD technique and highlights its merits and demerits over shake-table technique.

Many existing buildings are irregular in plan or elevation because of asymmetric placement of masonry infills. The stiffness of masonry infill is a considerable value relating to that of the structure. Produced torsion from eccentricity because of infill stiffness leads to extra forces and deformations in structural members and diaphragms. An appropriate alternative to solve this problem especially in existing buildings is using dampers. Dampers can enhance structural performance by reducing seismically induced lateral displacements and by reducing inelastic behavior of beams and columns. In this paper some simple models are used to show structural modeling and a conceptual discussion is presented on the numerical results. An accurate model for masonry infill has been used in structural model. Numerical results show the efficiency and high performance of added dampers to reduce the torsion effects in the structural elements.

One of the efforts to produce more environmentally friendly concrete is to reduce the use of OPC by replacing the cement in concrete with geopolymers. In geopolymer concrete no cement is used, instead fly ash and alkaline solutions such as sodium hydroxide (Na OH) and sodium silicate (Na2O, SiO2) and potassium hydroxide (KOH) are used to make the binder necessary to manufacture the concrete. One tone of fly ash can be utilized for manufacturing about 2.5 cubic meter of high quality Geopolymer concrete. Test experiments proved as fly ash based Geopolymer concrete has excellent Compressive strength, suffers very low drying shrinkage, low creep, excellent resistant to sulphate attack and good acid resistance. Trial mixes were done and noted the properties of the concrete both in fresh state and in hardened conditions. The workability of the concrete in terms of slump and compacting factor are observed to be excellent. The geopolymer concrete in fresh state observed to be highly viscous and good in workable. Collapsed slump was observed with compaction factor of 0.95. Cube compressive strength of the geopolymer concrete cubes verified at the age the concrete 28 days from the date of their casting. Based on the test results of the trial mixes, this experimental study is carried out for 5 different mix proportions of fly ash to alkaline chemical ratios of concrete specimen. Test specimen of standard sizes of cubes (30nos), cylinders (30nos), and prisms (15nos) were cast and tested for workability in terms of slump and compacting factors in fresh state and for mechanical properties such as Compressive Strength, Splitting Tensile Strength, Flexural Strength, and Modulus of Elasticity of concrete in hardened state. The test experiment proved that a concrete of compressive strength of 30MPa could be achieved in geopolymer concrete by adopting alkaline solution to fly ash ratio of 0.50 at 16 molarity of Na OH.