Panuwat Joyklad

STRUCTURAL DESIGN GUIDELINE FOR TSUNAMI EVACUATION SHELTER

The tsunami that hit the Andaman beach of Thailand on 26 December 2004 demonstrated the need for safe evacuation shelter for the public. However, there exists no guideline for designing such a shelter. In response to this need, the Department of Public Works and Town & Country Planning (DPT) funded a project to develop the guidelines for designing tsunami shelters. The results of the project have been published as a design manual for tsunami resistant shelter. In this paper, the design approaches for such tsunami shelters are described. The shelters are classified into two categories: (1) shelter in the area where large debris is unlikely and (2) shelter in the area where large debris is likely. In the former case, a static load of a certain magnitude representing small-to-medium debris is assumed to act at random points on the structure at the inundation depth. In the latter case, the work-energy principle is adopted to balance kinetic energy of large moving mass with the work done through energy-absorbing devices installed around the perimeter of the lower floors of the building. In both cases, the structure consists of a main inner structure and an outer protection structure. The function of the main structure is to provide usable spaces for evacuees, whereas the outer protection structure protects the inner structure from debris impact. The main structure is designed to be either elastic or with a low acceptable damage level. The structural framing of the main and the protection structures can be concrete or steel structures that are capable of resisting lateral forces. The major difference between the two types of building lie in the way the outer structure is connected to the inner one. In the first category, the connector is rigid so that both the inner and outer structures resist the load together. In the second category, energy-absorbing connectors are used to absorb the impact energy. The structure must, therefore, be analyzed using a nonlinear static approach. The design guidelines for both building types are described conceptually in this paper.

Confinement of Concrete by Rope

This study presents results of an experimental investigation conducted to investigate the axial behavior of natural rope confined concrete. Natural ropes such as coir, coconut and hemp ropes are easily available both in developing and developed counties. In this study, small scale concrete columns were confined using natural rope made of hemp fibers. The hemp rope was applied in three different thicknesses i.e. one layer, two layers and three layers. Both confined and un-confined concrete columns were tested under monotonic axial compression. The results indicate that rope confinement is very effective method to enhance ultimate strength and strain of confined concrete. The confinement level has a significant effect on strength and ductility of rope confined concrete. There is found significant increase in strength and ductility of concrete with an increase in the confinement level. Keywords—concrete, column, confinement, rope, strength and strain

Investigation of Gamma Ray Shielding and Compressive Strength of Concrete Containing Barite and Ferrophosphorous

This work emphasizes on the improvement of the gamma shielding ability of concrete using heavyweight materials of barite and ferrophosphorous. The physical properties and chemical composition of the selected aggregate materials were also studied. The specific gravity test results suggested barite and ferrophosphorous show excellent characteristics for improving shielding ability due to their high specific gravity of 4.21 and 5.35, respectively. The samples which applied barite and ferrophosphorous as aggregates, show high densities of 3,233 kg/m3 and 4,288 kg/m3, respectively. The sample applied ferrophosphorus material as an aggregate, had the highest linear attenuation coefficients with the highest density. The computed linear attenuation coefficients indicated higher values when compared with measured values due to low homogeneity of samples.

Investigation of Gamma Radiation Shielding of Concrete Containing Blast Furnace Slag Waste via Experimental and Calculation Methods

This study aims to evaluate gamma-ray shielding characteristics of concrete produced from blast furnace slag. The chemical and physical properties of the aggregates including the chemical composition and specific gravity were investigated to evaluate their radiation shielding properties. The samples were prepared with a cement content of 400 kg/m3, a water to cement ratio of 0.4, and fine aggregate of 43% and coarse aggregate ratio of 57%. Blast furnace slag was replaced with sand at 25%, 50%, 75% and 100% by volume to improve the shielding properties. The compressive strengths at 3, 7 and 28 days and the unit weight of the prepared samples were determined. The linear attenuation coefficient was measured and calculated at photon energies of 0.662 MeV, 1.17 MeV and 1.33 MeV. The WinXCom program was employed to calculate the attenuation coefficient from the chemical composition of samples and the results were compared to the measured results. The study results suggest that the use of blast furnace slag is effectively in improving the compressive strength and shielding properties of concrete. The increase of blast furnace slag caused an increase in the linear attenuation from 0.190 cm-1 to 0.210 cm-1 at 0.662 MeV.

Mechanical Properties of Fiber Reinforced Concrete

This study presents results of an experimental investigation conducted to investigate the mechanical properties of sisal and glass fiber reinforced concrete. Four basic concrete mixes were considered: 1) Plain concrete (PC) containing ordinary natural aggregates without any fibers, 2) sisal fiber reinforced concrete (SFRC), 3) sisal and glass fiber reinforced concrete (SGFRC), 4, glass fiber reinforced concrete (GFRC). Investigated properties were compressive strength, splitting tensile strength, flexural tensile strength and workability. The results of fiber reinforced concrete mixes were compared with plain concrete to investigate the effect of fibers on the mechanical properties of fiber reinforced concrete. It was determined that addition of different kinds of fibers (natural and synthetic) is very useful to produce concrete. The addition of fibers was resulted into higher compressive strength, splitting and tensile strength. However, the workability of the fiber reinforced concrete was found lower than the plain concrete due to the addition of fibers in the concrete.

Performance Enhancement of the Existing Bridges due to Overweight Vehicles with Multi-Axle Loading

This article presented the analytical results focused on the responses of existing bridges in Thailand subjected to overweight vehicles. The bridges, span lengths ranging from 5 to 20 meters, were loaded by the overweight vehicles with multi-axle loading having gross weight of 400 tons. The rating factors of bridges were also performed. The bridge strengthening methods using carbon fiber reinforcement polymers and intended settlement technique were also presented.The results indicated that the load rating factors were increased and conformed to the load rating standards. The results of this study would be a reference data to establish an alternative plan of bridge strengthening to improve the safety of the bridges under a moving of overweight vehicles.

Appraisal of Strengthening Cost for Increasing Flexural Strength of Reinforced Concrete Slab Bridges in Thailand

The highway live loadings, HS20-44, stipulated by Association of State Highway and Transportation Officials (AASHTO) are different from Thai truck weights according to government gazettes issued by Department of Highways. This article aimed to study the strengthening costs of the bridges due to Thai trucks. The reinforced concrete solid slab bridges with the span length ranging from 5 to 10 meters were selected to study. It was found that the bridge responses due to Thai trucks were greater than those from AASHTO loads. The average strengthening costs were approximately 6,958 Baht/sq.m and highest at 7 m-span length. The results of this study would be a reference data to create an alternative plan for bridge strengthening in Thailand in order to sustain the bridge safety level recommended by AASHTO.