జర్నల్ ఆఫ్ స్టీల్ స్ట్రక్చర్స్ & కన్స్ట్రక్షన్

High strength bolts are widely used as a connector of steel member for steel structure. When the torque shear type high strength bolt is fastened, a pin-tail of the bolt is twisted off. The clamping force of the high strength bolt is normally carried out with a visual inspection, so it is uncertain to measure the clamping force quantitatively. To solve this problem, this study developed a method to identify the clamping force of high strength bolt at a digital mode. The new method identify the induced tension is to analyse the accumulated electric energy applied to high strength bolts until the pin-tails are broken by electric torque wrenches. Valuations of bolt clamping forces and accumulated current data were collected through various experiments. The function of accumulated current data using regression analysis was conducted with various values of bolt diameter. The function of accumulated current data by various values of bolt diameter considering torque wrench rpm was conducted by using regression analysis. The measuring deviation between the values measured by a tension meter and those estimated by a trial product of a measuring device developed in this study is only around 4%. Also, as a result of the research, the trial product is developed including algorithms that calculate clamping force according to the different bolt diameter and electric wrench types.

A washer is a thin plate with a hole that is normally used to distribute the load of a threaded fastener, such as a screw or nut. The washer used in automotive engine component is of split or spring lock washer. A ring split at one point and bent into helical shape. The benefit of spring lock washers lies in the trapezoidal shape of the washer. When compressed to loads near proof strength of the bolt, it will twist and flattern. This reduces the spring rate of the bolted joint which allows it to maintain more force under the same vibration levels. This prevents from loosening. The steel washer is one of the critical safety component for automobile engine and its failure may cause severe safety issue. Before subjecting to manufacturing the washer undergoes different process lines (Wire Rod → Drawing → Annealing → Pickling → Flattening → Spring Washer → Single Spring Washer). After manufacturing of washer toughness test is done to find out the metallurgical soundness and surface quality of the washer. In this toughness test the washer in a vice with the split ends free and straight above the vice jaws, a 90° segment of the free end is gripped with a wrench and bent. Washers should withstand twist test through a 90° angle without signs of fracture. The present paper highlights premature failure of automotive washer which failed during twist test. From the analysis, it has been observed that the distribution of spheroidized carbide is more uniform in good samples than that of rejected samples. Hardness profile variation was observed between good and bad spring samples. Overall investigation does not indicate any problem related to supplied wire rod material quality as no wire breakage problem observed. Inhomogeneous annealed structure in flat wire seems to result into variation in washer performance during twist test.

The aim of the research was to enhance the mechanical and corrosion properties by adding coconut fibre in the concrete. Different compositions of concrete mixtures using Ravi and Chenab sand with and without fibre have been prepared. The mechanical properties were evaluated by compression and pull-out strength while corrosion properties by measuring half-cell potential before and after exposing to the different time duration in marine environment. As the different concrete possesses the complex properties, thus by the addition of fibres, improvement in all properties is not observed. The improved swell and crack resistance was also notified. However, adverse effects were observed in the compressive strength after introduction of fibres. Cumulatively, better corrosion resistance, 20% lesser compressive strength, 17 % higher pull-out strength and higher moisture absorption was observed for fibre reinforced concrete as compared with plain concrete.

Dynamic stresses generated by geological agents such as earthquakes, sand storms and hurricanes causes great damages to the structures. In this research dynamic loads the effect of generated by these geological agents have been taken into account for the performance base evaluation and design of rigid steel frames. The effect of fundamental periods on the design of these frames taking into account the variation in the behaviour factor and drift limitations is highlighted. The periods are obtained from the modal dynamic analysis; their performances were tested through nonlinear pushover analysis and these are then compared with the periods obtained from codified formulations. The weight of the designed frames are normalised with respect to the modal periods. It is observed that as the drift limitation varies from the lower limit (relaxed one) to the upper limit (stringent one); the fundamental period of the frames decreases and so the stiffness of the frame increases due to the members (beam and columns) sizes. Furthermore, it can be noted that the periods calculated from the codified formulations are in the same range to the one obtained from the modal analysis when the strict drift limit is incorporated.