A set of probabilistic seismic hazard maps for Thailand has been derived using procedures developed for the latest US National Seismic Hazard Maps. In contrast to earlier hazard maps for this region, which are mostly computed using seismic source zone delineations, the presented maps are based on the combination of smoothed gridded seismicity, crustal-fault, and subduction source models. Thailand's composite earthquake catalogue is revisited and expanded, covering a study area limited by 0 • -30 • N Latitude and 88 • -110 • E Longitude and the instrumental period from 1912 to 2007. The long-term slip rates and estimates of earthquake size from paleoseismological studies are incorporated through a crustal fault source model. Furthermore, the subduction source model is used to model the megathrust Sunda subduction zones, with variable characteristics along the strike of the faults. Epistemic uncertainty is taken into consideration by the logic tree framework incorporating basic quantities, such as different source modelling, maximum cut-off magnitudes and ground motion prediction equations. The ground motion hazard map is presented over a 10 km grid in terms of peak ground acceleration and spectral acceleration at 0.2, 1.0, and 2.0 undamped natural periods and a 5% critical damping ratio for 10 and 2% probabilities of exceedance in 50 years. The presented maps give expected ground motions that are based on more extensive data sources than applied in the development of previous maps. The main findings are that northern and western Thailand are subjected to the highest hazard. The largest contributors to short-and long-period ground motion hazard in the Bangkok region are from the nearby active faults and Sunda subduction zones, respectively.T. Ornthammarath (B) ROSE School,

Strut and Tie Model (STM) has been widely used for the design of disturbed region and non flexural members in RC structures. Pile cap is typically a disturbed region with small length to depth ratio, hence ordinary flexural theory for beams cannot be applied to it. In this research, six pile caps were designed for certain theoretical ultimate loads on the basis of STM. These pile caps were tested on four simply supporting piles. Loads were applied at the centre of pile cap. The experimental values were compared with the theoretical capacities of the pile caps on the basis of STM. It has been observed that STM has provided a reliable solution for predicting the shear strength of the four-pile caps and the experimental values fall very close to the theoretical values based on STM.

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This paper presents the outcome of a research study aimed at the performance evaluation of rice husk ash as partial replacement of cement in sandcrete blocks used as masonry units. Rice husk from the rice cultivated in the North of Pakistan was used in the study. It was first combusted in a locally manufactured incinerator to convert it into rice husk ash (RHA) and then finely ground to powder form for use with cement. Blocks with the size of 305×203×152 mm were molded with 0, 10, 30, 40 and 50% replacement of cement with RHA to find compressive strength at 3, 7, 14 and 28 days age of curing. The results showed that water requirement for the required workability of the sandcrete increased along with the RHA content, whereas the compressive strength decreased with increase in RHA content. However, the comparison of compressive strengths of RHA sandcrete blocks with the strength of commercial concrete blocks available in the market and used as masonry units in Pakistan showed that sandcrete blocks having the sand to binder ratio of 1:8 and using up to 40% of RHA as replacement of cement gave larger compressive strength than that of commercial concrete blocks and only marginally lower strength for 50% replacement.

The response of a helical strand is difficult to model theoretically, as it involves lengthy mathematical formulations. It is highly desired by the practicing engineers to have a simple and reliable method for the prediction of bending stiffness of multi-layered strands. A method for the estimation of bending stiffness of large diameter multi-layered strands has been proposed in this paper. The development of this method was carried out using significantly large number of parametric studies on a variety of strand construction which were also validated using the experimental data. The proposed method is simple in nature for direct engineering applications which provides an effective tool for calculating effective bending stiffness of a strand subjected to any bending curvature.