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This paper presents an assessment study of traffic-induced ground vibrations and their effects on masonry-type historic structures in Ayutthaya Historical Park, a UNESCO World Heritage Site in Thailand. The first objective is to propose a practical prediction of the attenuation rate of vibration for risk management of the monuments located along roadsides in the city. The attenuation of vibration waves traveling from traffic sources and the intensity of ground vibrations were determined by in situ vibration measurement. The results from the investigations in the Ayutthaya area were compared with those obtained from other sites having different characteristics of subsoil classified by the average shear wave velocity (Vs). It was found that the attenuation rates at a long distance from the source tend to be dependent on soil property in terms of Vs of subsoils. The attenuation curves derived from the regression analysis are proposed for risk management from the vibration of the heritage site. The second objective is to assess the effects of traffic vibrations on historic structures. The highest amplitude observed in Ayutthaya was within the recommended vibration criteria for historic buildings. In addition, finite element analysis of a 3D stupa model revealed that the stresses resulting from the ground vibration records induced by traffic was lower than the strength of ancient brick and mortar. [ABSTRACT FROM AUTHOR]

This paper presents the case study of a collapsed riverbank protection structure, located in the curvature of the watershed along the Pasak river in Saraburi province, Thailand. Although efforts have been made to twice rehabilitate this collapsed structure, the rebuilt protection structures were unstable to prevent progressive collapse damage and the causes of their failure remained elusive. The project team was engaged to carried out the site investigation and finite element analysis prior to providing the remedial approach on the collapsed structure. The outcome from this study reveals that the natural disaster events were the main causes of the structure failure. During the rainy season, water flowed into the river from upstream farmlands by crossing the backfill of the riverbank protection structure. Seepage forces were thus developed in the direction of inflows, which resulted in reduced stability of the riverbank protection structure. Furthermore, the strong currents in the river continuously scoured the banks, undermining the natural slope in front of the riverbank protection structure, resulting in soil erosion in the passive zone and instability of the protection structure. Based on these two causes of failure, a remedial solution was devised using a new bored pile riverbank protection structure with the usage of geocomposites and ripraps. Geocomposites and ripraps were installed at the back and front of the bored pile walls to relieve the structure from seepage forces and to prevent soil erosion, respectively. An adequate factor of safety against the external and internal failure of the new riverbank protection structure was verified by finite element modeling and the results confirmed that the structure was safe. [ABSTRACT FROM AUTHOR]

Prestressed concrete (PC) sleepers are used in modern railway systems worldwide. Although the PC sleepers are durable under harsh environmental conditions, frequent cracks can be found hindering the railway's capacities. This article investigates an improvement of placing steel stirrups in shear deficient PC sleepers commonly used in railways of Thailand. PC sleepers with a cross‐section of 258 × 205 mm2 varied with five different stirrup's ratios were tested under a three‐pointed bending load to observe the improvement of shear resistance. From the experimental results, the peak load of PC sleepers with stirrups can be enhanced from 14.1% to 21.2%, whilst the failure deformation can also be enhanced from 87.5% to 176.6%, compared with PC sleeper without any stirrup. With increasing stirrup's ratio, failure modes of PC sleepers were shifted from brittle shear to ductile flexural failures. Moreover, the PC sleepers with deformed‐bar stirrups exhibited better bond interfaces than that with rounded‐bar. Then, the proper stirrup's ratio and type of steel stirrups are recommended to enhance the shear resistance of the PC sleeper. In addition, a finite element analysis results based on advanced constitutive models and the fixed‐cracking approach showed good agreement with the results from experiment. [ABSTRACT FROM AUTHOR]

Rapid expansion of developed cities create problems mainly attributed to traffic congestions. Recently, Bangkok has faced rapid growth and the expanded neighborhoods require convenient public transport to be linked with central Bangkok and other parts of Thailand. Monorails can be an exceptional alternative to conventional skylines and subways thankfully to their excellent climbing abilities, lower noise, shorter constructions periods, and their capabilities to be adapted within limited spaces. Recently, Mass Rapid Transit Authority adopted monorail system to facilitate public in Bangkok's expanding neighborhoods. A four‐span continuous posttensioned girder system has been proposed for the straddle monorail system. Current study focuses on the structural response of full‐scale precast posttensioned (FPP) end girders in the proposed monorail system. Results suggested that the girder remained undamaged under service load while exhibiting a linear load versus vertical deflection response. Failure under ultimate load was accompanied by crushing of concrete, buckling of compression longitudinal bars and posttension tendons at the midspan. Further, experimental rosette strains suggested that concrete strains remained well below the ultimate of strains in the vicinity of high shear zones of the girder. Therefore, these results augment that the proposed design practice is safe against shear and the proposed girder can safely be used as the end girder in four‐span straddle monorail system. Nonlinear analysis of the girder was performed using advanced tool for engineering nonlinear analysis by adopting its built‐in constitutive laws for concrete and steel reinforcement. Predicted analytical response of FPP was in good agreement with experimental results in terms of load‐deflection curves, crack patterns, and failure mode. [ABSTRACT FROM AUTHOR]

This paper presents the case study of the collapsed riverbank protection structure along the Pasak river in Saraburi province, Thailand. The site investigation and finite element analysis using PLAXIS 2D results show that the failure occurred in sliding mode due to the natural forces. During the rainy season, water flow from the farmlands to the river by crossing the backfill of the retaining wall. Hence, seepage force was developed in the direction of the flow and induced the stability of the riverbank protection. Furthermore, the rivers and streams continuously scour the banks and undermined the natural slope, which caused the soil erosion in passive zone and resulted in instability. Based on these causes of failure, a new reinforced retaining wall structure using bored pile, geocomposite, and riprap at the front of retaining wall to protect the circular failure mechanism, seepage forces, as well as soil erosion and sedimentation, respectively was designed. The finite element verification on the new retaining wall structure showed that this structure had a sufficient factor of safety against the external and internal slope failure. [ABSTRACT FROM AUTHOR]