ASSESSMENT OF SOLAR ENERGY POTENTIAL FOR A RADIALLY STAGGERED HELIOSTATS FIELD USING SUN TRACKING METHOD

This article deals with the potential assessment of tower type solar thermal power system. An algorithm was developed to employ sun-tracking method, which provides the characteristic angles of the heliostats such that the incoming beams of sun rays are reflected to the receiver. A suite of MATLAB code was developed to implement the mathematical models for a quick evaluation of solar energy potential in a radially staggered heliostat field for the capital city of Kingdom of Saudi Arabia, Riyadh. An existing clear-sky model in the literature was used to compute hourly insolation. Optical efficiencies and heat collected by the receiver (from individual heliostat in the field on hourly basis) were computed and the monthly-averaged daily results were presented zone-wise and for the complete heliostat field. It was observed that the optical efficiency of the heliostat decreases with increasing distance from the receiver tower; this was due to increasing spillage of the reflected rays and decreasing cosine efficiency with increasing distance of the heliostat from the receiver tower. Results showed that annual average optical efficiency of the field is nearly forty-nine percent.

TOPP LEONE WEIBULL LOMAX DISTRIBUTION: PROPERTIES, REGRESSION MODEL AND APPLICATIONS

A new four-parameter lifetime distribution (called the Topp Leone Weibull-Lomax distribution) is proposed in this paper. Different mathematical properties of the proposed distribution were studied which include quantile function, ordinary and incomplete moments, probability weighted moment, conditional moments, order statistics, stochastic ordering, and stress-strength reliability parameter. The regression model and the residual analysis for the proposed model were also carried out. The model parameters were estimated by using the maximum likelihood criterion and the behaviour of these estimated parameters were examined by conducting a simulation study. The importance and flexibility of the proposed distribution have been proved empirically by using four separate data sets.

CARRIED BAGGAGE DETECTION AND CLASSIFICATION USING MULTI-TREND BINARY CODE DESCRIPTOR AND SUPPORT VECTOR MACHINE

Automatic video surveillance systems have gained significant importance due to an increase in crime rate over the last two decades. Automatic baggage detection through surveillance camera can help in security and monitoring in public places. A detection algorithm for humans (with or without carrying baggage) is proposed in this paper. Detection in the proposed method can be achieved by employing spatial information of the baggage of various texture patterns with locus to the human body carrying it. To extract the features of body parts (such as head, trunk and limbs), the descriptor is exhibited and trained by the support vector machine classifier. The proposed approach has been widely assessed by using publically available datasets. The experimental results have shown that the proposed approach is viable for baggage detection and classification as compared to the other available approaches.

EFFECT OF HUMAN HAIR FIBRES ON STRENGTH CHARACTERISTICS OF CONCRETE

Human hair fibres (HHFs) are made of non-degradable matter. These fibres possess high tensile strength and are available in abundance at very low cost. The use of HHFs in concrete structures may increase its capacity to resist tensile stresses which are caused by bending moments. This paper presents a study to investigate the effects of HHFs on concrete strength characteristics. Experiments were conducted on concrete cylinders to measure the compressive strength and split tensile strength while prisms were used to calculate the modulus of rupture. Three percentages of HHFs (one percent, 1.5 percent and two percent by weight of cement) were mixed to prepare the concrete samples. Mixes without HHFs were employed as control mixes. The obtained results indicated that with the addition of 1.5 percent HHFs, concrete compressive and split tensile strengths were increased by twenty-nine percent and fourteen percent, respectively. The same amount of HHFs increased the modulus of rupture and modulus of elasticity by twenty-three percent and nine percent, respectively.

EFFECTS OF STRUCTURE HEIGHT ON SEISMIC DEMAND OF MOMENT-RESISTING REINFORCED CONCRETE FRAMES CONSIDERING SOIL-STRUCTURE INTERACTION

Forces and displacements induced in a building due to structural responses to earthquake excitation are called seismic demands which depend upon the input motion, structural characteristics, site effects and the interaction of structure with soil. Structural response of three laterally non-controlled moment-resisting reinforced concrete frame structures with three different soil conditions are have been investigated in this paper. The soil conditions include loose soil, medium soil and rigid ground. The soil-structure interaction of low-, mid- and high-rise frame structures with the above mentioned soil types was analysed by performing nonlinear response history analyses. A set of eleven earthquake motions was employed in the analyses and maximum structural seismic demands for the frame structures were calculated. It was found that pressure-independent relatively loose sandy soils are not very critical for low-rise structures. On the other hand, pressure-independent relatively loose sandy soils and pressure-independent medium sandy soils are highly critical for mid-rise and high-rise structures, respectively. Categorisation of the soils is performed based on the value ranges of a series of constitutive parameters. Further, fixity of the base is most effective in controlling storey displacements until approximately one-third of the structure height. Medium soil leads to highest maximum base shears in low-rise structures while fixed-base and medium cases, and fixed base state control the behaviours of mid-rise and high-rise structures, respectively.

DUCTILITY FACTOR OF REINFORCED CONCRETE FRAME WITH WEAK BEAM-COLUMN JOINT

Code requirements are usually fulfilled during the design of a building. On the other hand, reinforced concrete (RC) frames (particularly in the developing regions of the world) are found deficient due to unregulated constructions. Majority of such deficient structures lack shear reinforcement in beam-column joints. Collapse of these deficient buildings (as a result of limited ductility) triggered many socio-economic and human losses which is evident from recent earthquake disasters. This paper presents an experimental study which was conducted on a 1:4 reduced scale three-storey RC special moment resisting frame (SMRF) lacking shear reinforcement in the beam-column joints. The lack of confinement bars causes shear hinging of joints that reduces the displacement ductility of the frame. Shake-table tests were conducted on test model that was subjected to acceleration time history of 1994 Northridge earthquake, having a peak ground acceleration of 0.57g. The acceleration was linearly scaled to multiple levels and to sinusoidal base excitations of various frequencies and displacements. Moderate to severe damage at each storey level was observed in the joint panels due to the lack of lateral reinforcing ties in the joints. The data obtained from shake table tests were processed and analysed to develop a lateral force-deformation capacity curve, which was bi-linearized as an elasto-plastic curve to compute various response parameters of frame. The ductility factor (Rμ) of the tested model was found to be equal to 1.95, which is thirty-five percent less than the code recommended value of Rμ for RC SMRF structures.

SEISMIC PERFORMANCE ASSESSMENT OF CONFINED ADOBE MASONRY STRUCTURES

This paper presents shake-table tests which were performed on two 1:3 reduce-scaled adobe masonry models confined with vertical and horizontal bands. The model AM1 consisted of bands (tie beam) at sill, lintel and eave levels, and lightly reinforced concrete (RC) columns at the corners. The model AM2 was similar to AM1 except that RC columns at the corners were not provided in this model. The models were subjected to sinusoidal base motions for studying their seismic performance. The lateral force-deformation capacity curves for both the models were developed and were bi-linearized to compute the response parameters including stiffness, strength, ductility and response modification factor (R). Seismic performance levels of both the models were defined and their seismic performance assessment was carried out to evaluate their suitability in different seismic zones. The use of vertical columns in the AM1 model considerably increased its lateral strength as compared to the AM2 model. Although R factor of 2.0 has been recommended for both the models, seismic performance of the AM1 model was found better in all seismic zones due to high lateral strength of this model.

EFFECTS OF WEB OPENINGS ON SHEAR BEHAVIOUR OF NORMAL AND INTERNALLY STRENGTHENED CONCRETE BEAMS

Web openings in reinforced concrete (RC) beams are provided to pass utility pipes and ducts through them. This causes high stresses (with local cracking) around the transverse web openings, which may lead to reduction in ultimate strength and stiffness of RC beams. Internal strengthening with shear reinforcement can increase ultimate strength of the beam with web openings. This paper presents an experimental study which was conducted to investigate load carrying capacity, mid-span deflection and failure modes of beams with web openings. A total of eighteen RC beams were included in the testing programme, which were tested under two-point loading. The beams contained both pre-planned and post-planned web openings. Experimental results showed that ultimate load of the beams decreased from forty-two to sixty-seven percent due to the presence of web openings in the shear zones. Shear strength of the beams with pre-planned web openings increased by thirty-six percent and one-hundred two percent as compared to the reference beam due to the increase of shear reinforcement by one-hundred twenty-two percent and three-hundred three percent, respectively. Similarly, increase in shear capacity up to six percent and fourteen percent was found for the beams with post-planned web openings due to the aforementioned increase in the area of shear reinforcement, respectively. The ultimate load carrying capacity was also compared with the theoretical models. Internal strengthening and pre planned opening were found effective for providing web openings in the beams.

INVESTIGATION OF EFFECTS OF RECYCLED AGGREGATES AND BLAST FURNACE SLAG ON PROPERTIES OF SELF-COMPACTING CONCRETE

The effects of simultaneous use of recycled aggregates and ground blast furnace slag as a percentage of cement-constituting materials on different properties of fresh self-compacting concrete (SCC) are investigated in this study. To this end, three series of SCC mixtures with a fixed volume of cement paste equalling 380 ltr/m3 (2.36 gal/ft3) and the replacement ratio of coarse aggregates (fifty percent and one hundred percent) and total aggregates (zero percent, fifty percent and one hundred percent) were prepared. The water content ratios in the first, second and third series were 0.4, 0.45, and 0.5, respectively. The results of the compressive strength tests for 7-day, 14-day and 28-day cubic specimens and compressive strength and Brazilian test results for 28-day cylindrical specimens were used as control parameters governing the SCC resistive quality. The results of fresh SCC tests (including slump-flow and T50 tests, V-funnel test, and L-box test) showed that the negative effect of recycled fine aggregates on fresh SCC properties is significantly more than that of recycled coarse aggregate. However, recycled SCC with acceptable properties can be obtained with a slight increase in the amount of superplasticisers used in the presence of slag.

A STEP TOWARD DEVELOPMENT OF GENERIC FRAGILITY CURVES

A phenomenon (failure) is considered as the change of state of the system (structure) between the origin (hazard threshold) and the destination (failure) points. The survive and the lost ratios of the system characteristics (stiffness) are defined in this paper in terms of stiffness, and the survive and failure (phenomenon) functions. The phenomenon functions are defined (in turn) in terms of the system identification parameter (state variable) and two control parameters. These parameters were calibrated by mapping them on four selected key points including origin, quarter point, middle point and end points in the system behaviour space. The failure function was used as fragility function. The validity of the work was verified by comparing the results with the fragility curves of four nuclear power plant containment vessels.