Engineering Journal of Research and Development

FLEXURAL BEHAVIOR OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH EXTERNAL POSTTENSION GFRP REBARS

Kongthap Shinwanit — 2024-09-26

The method of reinforced concrete structures with external posttension has proven to be highly effective. In modern times, fiber-reinforced polymer has replaced traditional prestressed concrete steel strand, addressing concerns related to corrosion and durability. This research aimed to examine the flexural behavior of reinforced concrete beams strengthened using external posttension glass fiber-reinforced polymer tendons. The research focused on determining the appropriate percentage ratio for prestressing. Three beam specimens were tested: one without external prestressing (control beam) and two strengthened using external prestressing glass fiber-reinforced polymer tendons. The concrete beams measured 150 300 2500 millimeter and were prestressed at 20% and 40% of the ultimate tensile stress of GFRP rebars. Test behavior includes Load–deflection curves, crack patterns, and the mode of failure. The results showed that the strengthened beams increased their flexural strength by 41%, and the external prestressing system raised the force that caused the first crack by 86%.

THE EFFECTS OF SEASONAL CHANGE ON THE ACCURACY OF FORECAST RAINFALL DATA IN THE UPPER PHETCHABURI RIVER BASIN

Nathpaphas Phoonuch — 2024-09-26

The objective of this study was to determine the effects of seasonal change on the accuracy of forecast rainfall data in the Upper Phetchaburi River Basin by the spatial and positional accuracy of forecast rainfall data from Numerical Weather Prediction-NWP model of Thai Meteorology Department comparing with ground rainfall data. Theses areal forecast rainfall data would be then used for the estimation of the forecast inflow of Kaeng Krachan Reservoir during the rainy season. In the study area, there are few rainfall stations because the area is the upstream part of river basin and all area are forests. For the data collection, daily rainfall data during July-October 2020, July - October 2021 and July-October 2022 were selected and two spatial estimation methods were used, Thiessen-polygon and inverse distance weighting in order to spatial compare with forecast rainfall from NWP model with selected three boundaries of grid forecast rainfall data namely d01 (18X18 km), d02 (6X6 km) and d03 (2X2 km). One days-forecasted rainfall data and compare positional accuracy with point-to-point of location of 6 ground rainfall stations were used. After that, the results of the spatial and positional rainfall estimation were examined by three accuracy indexes namely the Mean Error between the estimated value and the actual value (ME), Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). The result found that forecast rainfall from Inverse Distance Weighting were a little bit better in all forecasts of Thiessen Polygon methods. Both methods gave in line of MAE and RMSE index values, and the spatial rainfall estimates of the forecasted rainfall gave mostly higher values than the estimates from ground rainfall values. Forecast rainfall data with d03 (2X2 km) grid boundary is the most accurate result because it has a fine resolution of 633 grids in the Upper Phetchaburi basin. It gives better rainfall estimation results than point rainfalls. and in October there is the greatest discrepancy, because of the changing seasons. The wind has changed from the southwest monsoon to the northeast monsoon while in August there is the lowest discrepancy because it is in the rainy season that it rains regularly.

COMPARATIVE STUDY OF ACCURACY OF THREE-DIMENSIONAL MODELS OBTAINED FROM CLOSE-RANGE PHOTOGRAMMETRY USING ACTION CAMERA AND COMPACT CAMERA

Niyom Chaokhruea — 2024-09-26

By applying the lens distortion model proposed by [1] up to the K3 radial distortion coefficient level, this research study seeks to contrast the suitability of using action cameras versus compact cameras. The results indicate that the action camera achieved an accuracy level of ±8.7 centimeters, whereas the compact camera attained an accuracy level of ±0.2 centimeters. This significant difference in accuracy levels underscores the substantial disparity between the two types of cameras. The findings suggest that future research should focus on developing a more refined radial lens distortion model to enhance the correction level. Such advancements would enable action cameras to be utilized more effectively in engineering applications. Additionally, the study highlights that compact cameras can achieve very high accuracy, suggesting that with appropriate systematic error corrections, these cameras can yield valuable engineering results and can be applied in various practical scenarios.

EFFECTS OF MASONRY INFILL WALL MODELS ON VIBRATION PERIOD AND SEISMIC RESPONSE OF A BUILDING

Pakkapong Likhitsuwan — 2024-09-26

This research investigates the effects of infill wall models in building structures, modeled using equivalent struts, on the vibration period and seismic response through nonlinear response history analysis (NLRHA). Two types of building models are considered: one where the equivalent strut uses the modulus of elasticity based on recommended guidelines for nonlinear models, and another where the equivalent strut uses an adjusted modulus of elasticity to match the natural frequency measured from the actual building. Each type comprises both 2D and 3D models, and all four building models employ fiber sections to model nonlinear behavior. These models are analyzed with ground motions adjusted to match the target response spectrum. The results are discussed regarding shear forces, deformation, and changes in the vibration period. The study reveals that the building models using the modified modulus of elasticity for the equivalent struts exhibit higher seismic responses and an increase in the vibration period compared to models without the modified modulus of elasticity.

COORDINATE ADJUSTMENT OF CONTROL TARGETS IN THE CALIBRATION SHEET FOR UAV CAMERA CALIBRATION

Deeboon Methakullachat — 2024-09-26

Camera calibration for mapping from UAV is an important process for determining the camera interior orientation parameters, which are used as a bridge to link rays from points on the image to the outside world. The camera calibration which utilizes a calibration sheet plotted by an inkjet plotter is a method that is mostly used in general. A calibration sheet size is approximately the size of an A0 paper and consists of control targets distributed throughout the entire sheet. In reality, the locations of the control targets are not plotted correctly. The error generated by the plotter can reach as much as 2 millimeters for a one-meter distance. This paper presents a procedure to use a steel ruler, which is an accurate device for measuring distances and has higher accuracy than an inkjet plotter, to check for positional error of the control target. The error is then used to adjust the target coordinates. The analysis of error of the adjusted coordinates of control targets are also presented.

THICKNESS CONTROLLING OF GREEN TIRE PAINTING IN TIRE PRODUCTION

Jittra Rukijkanpanich — 2024-09-26

Green tire painting on the tire chafer is crucial for shaping the tires before the curing. The spraying of chemicals with uneven thickness causes defects as a result. Consequently, the research aimed to determine the control parameters for green inside painting (GIP), which involve the spray pressure, the angle of the spray gun, and the spray gun distance. The results of the experiment demonstrated that in the case of producing 16-inch nylon chafer tires, the spraying pressure should be set to 0.05 MPa, the spray gun angles at the upper, middle, and lower levels should be set to 150º, 30º, and 180º, respectively, and the spray gun distance should be set to pattern A. For 17-inch gum chafer tires, the recommended settings were a spray pressure of 0.03 MPa, an upper-level spray gun angle, a mid-level spray gun angle, and a lower-level spray gun angle of 120º, 30º, and 180º, respectively, as well as the spray gun distance setting pattern B. Finally, for 18-inch gum chafer tires, the recommended settings should be a spray pressure of 0.03 MPa, an upper-level spray gun angle, a mid-level spray gun angle, and a lower-level spray gun angle of 150º, 0º, and 180º, respectively, and the spray gun distance setting pattern B. After implementing the new green tire painting control, the defect decreased from 0.052% to 0.025%.