Lateral Loading Test of Reinforced Concrete Bored Pile in Stiff Clay and Near Slope

Staff residence of University of Phayao has been constructed near slope. The inhabitants in the residence are concerned about the lateral strength of the pile foundation during earthquake. This paper involves the evaluation of reinforced concrete bored piles of the residence under lateral loading. In field experiment, two full-scale bored piles were built near the slope of 1:1.5 adjacent to the residence. Two lateral load patterns that push the piles in and out were applied at the pile head. The maximum value of the lateral force was 65 kN representing the base shear force due to earthquake in Thailand. The test results show that the lateral displacements of the pile do not exceed 3 mm and stress in the longitudinal reinforcement is below the yield point. It is implied that the bored piles of staff residence can resist the lateral load imposed on the structure during an earthquake. For the analysis, the pile is modeled using frame elements and the surrounding soil is assigned by horizontal springs. The stiffness of springs is validated by comparing to the test results of the previous researches and this study. It is found that using the proper soil spring stiffness and flexural rigidity values in the structural pile analysis can capture elastic responses including the lateral displacement, bending moment and depth of inflection point

Laboratory investigation of the performances of cement and fly ash modified asphalt concrete mixtures

AbstractThe influence of filler materials on volumetric and mechanical performances of asphalt concrete was investigated in this study. The AC60/70 asphalt binder incorporating with cement and fly ash as filler materials was mixed with limestone following the Marshall mix design method. The filler contents of cement and/or fly ash were varied. The non-filler asphalt concrete mixtures of the AC60/70 and the polymer modified asphalt were prepared for the purpose of comparison. The investigation programme includes the indirect tensile test, the resilient modulus test and the dynamic creep test. The tests are conducted under the humid temperate environments. All tests were then carried out under standard temperature (25°C) and high temperature (55°C) by using a controlled temperature chamber via the universal testing machine. The wet-conditioned samples were prepared to investigate the moisture susceptibility. Results show that cement and/or fly ash were beneficial in terms of improved strength, stiffness and stripping resistance of asphalt mixture. In addition, the combined use of cement and fly ash can enhance rutting resistance at wet and high temperature conditions. The results indicate that the strength, stiffness and moisture susceptibility performances of the asphalt concrete mixtures improved by filler are comparable to the performance of the polymer modified asphalt mixture

การประเมินกำลังต้านแผ่นดินไหวของอาคารโดยคำนึงถึงโครงสร้างฐานรากเสาเข็มSeismic Evaluation of Building Considering Pile Foundation

บทความนี้นำเสนอผลการศึกษาเปรียบเทียบผลการประเมิน และผลตอบสนองของโครงสร้างอาคารต้านแผ่นดินไหวโดยใช้สเปกตรัมในพื้นที่จังหวัดพะเยา ด้วยแบบจำลองโครงสร้างอาคารที่มีเฉพาะโครงสร้างด้านบนเพียงอย่างเดียว และแบบจำลองที่มีทั้งโครงสร้างด้านบนและโครงสร้างฐานรากพร้อมกัน โดยโครงสร้างฐานรากได้ใช้เสาเข็มและสปริงเพื่อแทนผลของดินที่อยู่ด้านข้างเสาเข็ม ผลการศึกษาพบว่า แบบจำลองอาคารที่มีทั้งโครงสร้างด้านบนและโครงสร้างเสาเข็มพร้อมกัน ทำให้คาบธรรมชาติในโหมดพื้นฐานเพิ่มขึ้น และมีรูปแบบและสัดส่วนการสั่นไหวที่แตกต่างจากแบบจำลองที่ไม่มีเสาเข็ม แบบจำลองที่มีเสาเข็มมีสติฟเนสการต้านแรงด้านข้างลดลงแต่ไม่ได้ลดแรงต้านสูงสุดของอาคาร และถูกประเมินด้วยแรงแผ่นดินไหวที่ลดลงจึงพบระดับความเสียหายที่ลดลงด้วย ผู้วิจัยได้ทดลองเปลี่ยนลักษณะชั้นดินให้มีความแตกต่างกันพบว่า การคำนึงถึงการวิเคราะห์โครงสร้างอาคารที่คำนึงถึงโครงสร้างฐานรากจะช่วยลดแรงแผ่นดินไหวที่ใช้ประเมินได้มากในกรณีดินที่อ่อน แต่โครงสร้างอาคารจะมีการเสียรูปที่มากขึ้น ดังนั้นการจำลองโครงสร้างอาคารจำเป็นต้องพิจารณาโครงสร้างฐานรากในกรณีที่อาคารอยู่บนดินอ่อนเพื่อให้ประเมินสมรรถนะของของอาคารได้อย่างเหมาะสมThis article presents a comparative study of the evaluation results and responses of the building under seismic load using Phayao Province spectrum. The comparisons are made from the two different building models consisting of the model with the only super structure and the one with both super structure and pile foundation. The foundation model is constructed with frame elements and springs representing pile embedded in soil under lateral load. Based on the study results, the building model with pile foundation has higher natural frequency in fundamental mode shape and has different mode shapes and modal participation ratios compared with the building model without pile. The building model with pile tend to reduce the lateral stiffness but does not reduce the maximum lateral resistance. It was also assessed by the reduced seismic force and the lower level of damage was also found. The parametric study of the building model with pile foundation embedded in various types of soil indicated that, the model will significantly reduce seismic evaluation force, especially in case of soft soil but the model has more deformation. The building model should consider sub structure, especially in case of soft soil, in order to evaluate the seismic performance of the building properly

Flexural performance and microstructural characterization of cement-treated sand reinforced with palm fiber

Sands are mixed with cement to create cement-treated sands (CTSs) for embankment and road materials in civil engineering works. However, CTS exhibits undesirable brittle behavior because the CTS can break suddenly after the applied stresses reach their peak strength. CTS reinforced by natural fibers is called CTSF. This paper aims to study the influence of palm fiber on the flexural performance and microscopic characterization of CTSF specimens. Palm fiber contents of 0.5, 1, and 2% by volume and fiber lengths of 10,20, and 40 mm were utilized. The four performances of CTSF are peak strength, residual strength, toughness, and equivalent flexural strength. The interaction mechanism of the CTSF fiber was examined using scanning electron microscopy. The results show that the palm fibers change the behavior of CTS from brittle to semi-ductile or ductile. The 1% fiber content and 40-mm-long fiber improve the flexural of unreinforced samples by a factor of 2.7. The best residual strength at a deflection of 2 mm is obtained from the specimen with a 2.0% fiber content and a 40 mm fiber length exhibiting the residual-peak flexural strength ratio of 1.0. All palm fiber-reinforced samples show softening behavior because an equivalent strength ratio is less than 100%. The 2% fiber content and 40 mm fiber length provide the best equivalent strength ratio since the equivalent strength ratios are enhanced by a factor of 20. The fiber content and length mainly affect the equivalent strength ratios. A single failure plane is seen for CTS and CTSF samples with low fiber content, whereas numerous cracks are observed for CTSF samples. Regarding failure mode and flexural performances, palm fiber inclusion is suitable as the base and subbase for the bound pavement structure in civil and pavement engineering works

Influence of partial substitution of metakaolin by palm oil fuel ash and alumina waste ash on compressive strength and microstructure in metakaolin-based geopolymer mortar

Geopolymer is recognized as an alternate binder that compounds silica-rich and alumina-rich materials as raw materials and is produced by alkaline activation. In general, biomass ashes in particular for palm oil fuel ash (POFA) is an ideal starting material on the grounds of its high silica concentration, while industrial by-products, especially alumina waste (AW) is also employed as starting material due to its high alumina content. The objective of this research is to address the effects on the compressive strength and also the microstructure of metakaolin-based geopolymer mortar studied through the adaptability of the substitution of metakaolin (MK) by POFA and AW. In order to investigate the effects of POFA and AW substitution on the polymerization reaction and its outcomes, metakaolin-based geopolymers were produced. The most recent data suggests that POFA and AW probably serve as feedstocks for geopolymers with a little strength reduction. The partial substitution of MK by POFA reduces the polymerization reaction rate while maintaining the same water/binder ratio. However, because of the long-lasting polymerization reaction, it is still obtainable to reach a significant degree of polymerization reaction and also provides a comparable 28-day curing age compressive strength for 20 % replacement of MK by POFA. Considering 10 % substitution of POFA by AW, it results in 22.08 % improvement in the compressive strength after 28 curing days. On top of that, the compressive strength development of the geopolymer sample was investigated using scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). It was discovered that the density and the compressive strength were induced by the particle morphologies, the surface area of POFA and AW, and the chemical composition as a result of the geopolymerization

Investigation on the tensile strength of Dendrocalamus sericeus, Phyllostachys makinoi, and Thyrsostachys oliveri bamboo: Experiment and simulations

Bamboo, being a natural and sustainable construction material with remarkable mechanical properties, warrants comprehensive study for efficient and safe engineering applications. However, there is limited research on its behavior, particularly in Thailand. Therefore, this paper investigates 102 Thai bamboo specimens from three species (Dendrocalamus sericeus, Phyllostachys makinoi, and Thyrsostachys oliveri) and two node conditions to examine their tensile mechanical properties and develop a bamboo constitutive model for finite element analysis. The test results indicate that specimens with nodes exhibit lower maximum tensile strength compared to those without nodes, with differences of approximately 86.68 %, 45.54 %, and 50.35 % for Dendrocalamus sericeus, Phyllostachys makinoi, and Thyrsostachys oliveri bamboo, respectively. Statistical methods were employed to gather data and predict tensile stress and strain at the specimen’s fracture point. A displacement-based formula was utilized to formulate the constitutive law for the proposed bamboo bar model. The accuracy and capability of the proposed model were verified through three numerical simulations: a convergence study, validation with experimental data, and analysis of bamboo applications in structural engineering. The results demonstrate good accuracy and capability, providing up-to-date local bamboo testing results in Thailand for future engineering applications