Brief summary of engineering doctoral thesis: Analysis of influencing parameters and basics of determining resistance factors of drilled shafts used in bridge substructures in Ho Chi Minh city

Objectives of doctoral thesis Analysis of influencing parameters and basics of determining resistance factors of drilled shafts used in bridge substructures in Ho Chi Minh city: Determine resistance factors according to soil base strength which is equivalent to methods presented in specifications being applied.
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Brief summary of engineering doctoral thesis: Analysis of influencing parameters and basics of determining resistance factors of drilled shafts used in bridge substructures in Ho Chi Minh city 1 MINISTER OF EDUCATION AND TRAINING UNIVERSITY OF TRANSPORT AND COMMUNICATIONS NGO CHAU PHUONGANALYSIS OF INFLUENCING PARAMETERS AND BASICSOF DETERMINING RESISTANCE FACTORS OF DRILLEDSHAFTS USED IN BRIDGE SUBSTRUCTURES IN HO-CHI- MINH CITY MAJOR: BRIDGE AND TUNNEL ENGINEERING CODE: 62.58.02.05.03BRIEF SUMMARY OF ENGINEERING DOCTORAL THESIS Hanoi-2014 2 This thesis completed at: Faculty of Civil Engineering University of Transport and Communications SUPERVISORS: 1. Assoc.Prof. Dr. Tran Duc Nhiem 2. Assoc.Prof.Dr. Nguyen Ngoc LongReviewer 1: Prof. Dr. Nguyen Nhu Khai, National University of Civil Engineering Vietnam.Reviewer 2: Prof. Dr. Nguyen Dong Anh, Institute of Mechanics Vietnam.Reviewer 3: Dr. Do Huu Thang, Institute of Transport Science and Technology Vietnam.Thesis is defended in front of the University-Graded Committee ofthesis evaluation according to Decision #1359/QĐ-ĐHGTVT, on date17th June 2014 signed by the Rector of University of Transport andCommunications on date………………….. 2014.Readers can find this thesis at: - Vietnam National Library - Library of the University of Transport and Communications 1 INTRODUCTION By applying statistics and probability and reliability theory toengineering foundations, the thesis proposes a pattern to determineresistance factors of drilled shafts used in bridge substructures based onstatistics characteristics of the ratio between real measured values andestimated values for Resistance (R) and load effect (Q). Then, by analyzingstatistics characteristics of the capacity based on 24 results of static axialcompressive load test of drilled shafts that were constructed by the wetmethod (bentonite) in cohesive and non-cohesive composite soils in Ho-Chi-Minh city, the thesis captures the determination of resistance factorsfor four different calculation methods of pile resistance design based on soilbase strength condition. Literature Review: Drilled shafts construction technology was first used in America (1890),in over the word (1950) and in Vietnam (1990). However, the calculationtheory has been developed more slowly. One of the trends in the world is toresearch new problems of applying statistics and probability theories andreliability theory to correct resistance factors based on statisticscharacteristics of the ratio between real measured values and estimatedvalues for Resistance (R) and load effect (Q) extracted from a reasonablenumber of construction projects. Research results are gradually applied toupdate and to implement for some clauses in standards or specifications anddesign instructions of developed countries such as in Europe, Japan…andAmerica. Over two more recent decades in Vietnam, accompanied with thedevelopment of infrastructure in great scale built in soft soil bases or inurban areas, drilled shafts foundations becomes one of the best solutions.The foundations are also widely applied in Ho-Chi-Minh city. However,there is not any backgrounds to determine resistance factors of drilledshafts based on analyzing statistics characteristics and reliability analysisusing current advanced theories. Therefore, studying of the backgrounds to determine the resistancefactors based on reliability analysis is new and attracts international anddomestic researchers. It is the reason why I selected this topic to research. 2 Thesis title: “Analysis of influencing parameters and bases to determineresistance factors of drilled shafts used in bridge substructures in Ho-Chi-Minh City”. Objectives: Determine resistance factors according to soil base strengthwhich is equivalent to methods presented in specifications being applied. Structure: Drilled shafts used in bridge substructures. Research Scope: Predictive resistance and real resistance obtained fromthe results of static axial compressive load tests for drilled shafts in Ho-Chi-Minh City casted in cohesive and non-conhesive composite soils (sand,sandy, clay, clay mud,...) by wet method; to determine general resistancefactors according to soil base strength condition for four different methodsof pile resistance design: 1) Russian Method specified in TCXDVN 205-98; 2) Japanese Method (JRA 2002 SHB -Part IV); 3) Reese&ONeill(1988) and 4) ONeill&Reese (1999). Problems relating to load statisticscharacteristics, general resistance factors for various types of soil, localareas, and type of structure as well as pile shalf and tip resistance factorsare not performed in this thesis and they are recommented for futurestudies. Scientific and practical meaning of the topic: - Apply advanced theories of statistics analysis and reliability topropose a pattern to determine resistance factors of drilled shafts based onstatistics data of the ratio between real measured values and estimatedvalues for Resistance (R) and load effect (Q). - The thesis has analyzed and determined statistics characteristics ofthe ratio between real measured values and estimated values; to determineresistance coefficients for the four methods from 24 static load test resultsof drilled shafts constructed in cohesive and discrete composite soils in Ho-Chi-Minh city subjected to static axial compression and other applicabledata. - Research results of the thesis can be used as reference documents indesign bearing capa ...