Volume 5: Ocean Space Utilization; Polar and Arctic Sciences and Technology; The Robert Dean Symposium on Coastal and Ocean Engineering; Special Symposium on Offshore Renewable Energy, 2007
With the growing energy needs of the world and the sustainable nature of wind energy this sector ... more With the growing energy needs of the world and the sustainable nature of wind energy this sector is a highly innovative growth industry. The past years have seen the industry develop and test not only more efficient, but also much larger wind turbines than those that are in current use. The next generation of wind turbines that are on the drawing boards are gigantic in size. These huge dimensions of the proposed wind turbines will put large demands on the foundations. As an increasing number of wind farms are being planned offshore in water depths of over 40 m, the combination of water depth and the increased windmill tower heights and rotor blade diameters create loads that make foundation design very complex. Moreover, offshore foundations are exposed to additional loads such as ocean currents, storm wave loading, ice loads and potential ship impact loads. All of these factors pose significant challenges in the design and construction of wind turbine foundations. This paper presen...
Factors that influence axial capacity of piles in sands such as soil parameters, pile parameters,... more Factors that influence axial capacity of piles in sands such as soil parameters, pile parameters, loading effects and installation effects are listed. Physical phenomena such as grain crushing, pile shaking, stress-redistribution and plugging which all influence pile capacity are also examined. To better understand the method of prediction, each parameter and the associated uncertainty is revisited. It is evident that these factors are inter-related and sometimes compensating. This discussion also draws attention to the influence that pile installation procedures can have on pile capacities and highlights the need for field experience with various pile installation procedures for designers. In summary, while the various available methods of pile capacity prediction are deceptively simple to use, the associated uncertainty of each method cannot be ignored. The possible savings generated by an improved method are too substantial "o ignore.
Seismic soil-pile-structure interaction (SSPSI) is a complex process involving several, simultane... more Seismic soil-pile-structure interaction (SSPSI) is a complex process involving several, simultaneously occurring and, sometimes compensating phenomena. The physical processes that occur when a pile supported structure undergoes earthquake loading consist of pore-pressure generation, ground deformation and subsequent cyclic degradation, strain rate effects and gap-slap mechanism. Modeling these physical phenomena numerically is a challenge. Of the various approaches available in practice, the p-y method for evaluating lateral pile response is by far the most common. However, at present, a consensus has not been established among practitioners on the appropriateness of using p-y curves for post-liquefaction analyses. This paper presents a discussion of available models and modifications to p-y relationships used to model soil response under seismic conditions. Predictions made with these models are then compared with actual load test data performed by others. It is concluded that further research is needed to quantify and predict gap formation, the stress-strain behavior of liquefied soils and to accurately evaluate non-linear bending resistance of steel encased concrete sections.
This paper presents the results of a pile installation and testing program for instrumented 30-in... more This paper presents the results of a pile installation and testing program for instrumented 30-in long, 3.5 in diameter steel pipe piles with wall thicknesses 0.120 in, 0.216 in, and 0.290 in, installed by jacking into Oklahoma Sand specimens created by pluviation in a CPT calibration chamber at the University of Texas. Continuous measurements of pile penetration, plug height and pile resistance were obtained as the piles were pushed into the sand specimens with the calibration chamber pressurized at 10 psi. The instrumentation involved a load cell, a position transducer, and an LVDT. For comparison purposes, an additional test was performed on a 3.5 in diameter closed end pile. This paper presents a description of the model pile installation facility, the instrumented piles, the model sand, the testing program, and, the test results obtained. The results of the testing program indicate that piles with thicker walls require less penetration to develop plugging. Pile capacities were also predicted using the conventional procedures and found to under-predict measured values. The differences are attributed to development of higher side friction caused by plugging.
Concrete cylinder piles are large diameter precast piles that are commonly used for water crossin... more Concrete cylinder piles are large diameter precast piles that are commonly used for water crossings and other marine applications that require foundations with high load resistance that are highly resistant to corrosion. With their high moment of inertia and corresponding high buckling resistance, concrete cylinder piles are well suited for sites where water depth and potential scour result in a long free-length of pile above mudline. This paper provides an overview of concrete cylinder piles, including a discussion of typical pile sizes and properties, fabrication methods, typical applications, advantages and disadvantages, and the unique design and construction issues relevant to this type of pile. The paper also describes common installation problems for this type of pile and typical remedial measures to address these problems. Finally, the paper illustrates pile design and installation issues with case histories from three recent bridge projects.
This paper presents the results of a pile installation monitoring and performance assessment prog... more This paper presents the results of a pile installation monitoring and performance assessment program for pile foundations supporting 14 piers and 2 abutments of the 1700-ft long bridge crossing over a river in Baltimore, Maryland. Dynamic measurements were conducted during installation and restrike of 16 test piles, one at each support location. The foundation piles were 30-inch diameter, 0.75 inch thick pipe piles at the piers and 24-inch diameter, 0.5 inch thick at the abutments. The piles at the piers were approximately 100 ft long and were designed to carry 260 kips service load with a factor of safety of 2.25. The piles were driven open ended into a variable site stratigraphy containing recent deposits of organic clayey silts near the mud line followed by loose to medium dense sand, with some silt, and then by soil deposits from the Cretaceous period consisting primarily of dense to very dense, poorly- to well graded sands and gravels and cobbles, with occasional seams of very hard to very stiff, low to moderate plasticity silts and clays. This paper presents the approach taken to evaluate the driven index piles and to develop criteria for driving production piles, and provides the Engineer with some data on pile driveability in Cretaceous soils in the Baltimore area, soil set-up effect, and an estimate of pile capacity.
Ballooning oil prices both in the United States and globally have brought alternative energy sour... more Ballooning oil prices both in the United States and globally have brought alternative energy sources including wind energy to the forefront. Offshore wind energy is fast becoming an attractive proposition because there are vast wind resources located offshore with little visual or noise impact to local communities. But developing these wind resources 15 to 30 km from shore would require large foundations which could be cost prohibitive. To make such a proposition cost effective requires even larger wind turbines. These large wind turbines will place large demands on the support structures and foundations. As an increasing number of wind farms are being planned offshore in water depths of over 50 m, the combination of water depth and the increased windmill tower heights and rotor blade diameters will create loads that make foundation design very complex. Moreover, offshore foundations are exposed to additional loads such as ocean currents, storm wave loading, ice loads and potential ...
Volume 5: Ocean Space Utilization; Polar and Arctic Sciences and Technology; The Robert Dean Symposium on Coastal and Ocean Engineering; Special Symposium on Offshore Renewable Energy, 2007
With the growing energy needs of the world and the sustainable nature of wind energy this sector ... more With the growing energy needs of the world and the sustainable nature of wind energy this sector is a highly innovative growth industry. The past years have seen the industry develop and test not only more efficient, but also much larger wind turbines than those that are in current use. The next generation of wind turbines that are on the drawing boards are gigantic in size. These huge dimensions of the proposed wind turbines will put large demands on the foundations. As an increasing number of wind farms are being planned offshore in water depths of over 40 m, the combination of water depth and the increased windmill tower heights and rotor blade diameters create loads that make foundation design very complex. Moreover, offshore foundations are exposed to additional loads such as ocean currents, storm wave loading, ice loads and potential ship impact loads. All of these factors pose significant challenges in the design and construction of wind turbine foundations. This paper presen...
Factors that influence axial capacity of piles in sands such as soil parameters, pile parameters,... more Factors that influence axial capacity of piles in sands such as soil parameters, pile parameters, loading effects and installation effects are listed. Physical phenomena such as grain crushing, pile shaking, stress-redistribution and plugging which all influence pile capacity are also examined. To better understand the method of prediction, each parameter and the associated uncertainty is revisited. It is evident that these factors are inter-related and sometimes compensating. This discussion also draws attention to the influence that pile installation procedures can have on pile capacities and highlights the need for field experience with various pile installation procedures for designers. In summary, while the various available methods of pile capacity prediction are deceptively simple to use, the associated uncertainty of each method cannot be ignored. The possible savings generated by an improved method are too substantial "o ignore.
Seismic soil-pile-structure interaction (SSPSI) is a complex process involving several, simultane... more Seismic soil-pile-structure interaction (SSPSI) is a complex process involving several, simultaneously occurring and, sometimes compensating phenomena. The physical processes that occur when a pile supported structure undergoes earthquake loading consist of pore-pressure generation, ground deformation and subsequent cyclic degradation, strain rate effects and gap-slap mechanism. Modeling these physical phenomena numerically is a challenge. Of the various approaches available in practice, the p-y method for evaluating lateral pile response is by far the most common. However, at present, a consensus has not been established among practitioners on the appropriateness of using p-y curves for post-liquefaction analyses. This paper presents a discussion of available models and modifications to p-y relationships used to model soil response under seismic conditions. Predictions made with these models are then compared with actual load test data performed by others. It is concluded that further research is needed to quantify and predict gap formation, the stress-strain behavior of liquefied soils and to accurately evaluate non-linear bending resistance of steel encased concrete sections.
This paper presents the results of a pile installation and testing program for instrumented 30-in... more This paper presents the results of a pile installation and testing program for instrumented 30-in long, 3.5 in diameter steel pipe piles with wall thicknesses 0.120 in, 0.216 in, and 0.290 in, installed by jacking into Oklahoma Sand specimens created by pluviation in a CPT calibration chamber at the University of Texas. Continuous measurements of pile penetration, plug height and pile resistance were obtained as the piles were pushed into the sand specimens with the calibration chamber pressurized at 10 psi. The instrumentation involved a load cell, a position transducer, and an LVDT. For comparison purposes, an additional test was performed on a 3.5 in diameter closed end pile. This paper presents a description of the model pile installation facility, the instrumented piles, the model sand, the testing program, and, the test results obtained. The results of the testing program indicate that piles with thicker walls require less penetration to develop plugging. Pile capacities were also predicted using the conventional procedures and found to under-predict measured values. The differences are attributed to development of higher side friction caused by plugging.
Concrete cylinder piles are large diameter precast piles that are commonly used for water crossin... more Concrete cylinder piles are large diameter precast piles that are commonly used for water crossings and other marine applications that require foundations with high load resistance that are highly resistant to corrosion. With their high moment of inertia and corresponding high buckling resistance, concrete cylinder piles are well suited for sites where water depth and potential scour result in a long free-length of pile above mudline. This paper provides an overview of concrete cylinder piles, including a discussion of typical pile sizes and properties, fabrication methods, typical applications, advantages and disadvantages, and the unique design and construction issues relevant to this type of pile. The paper also describes common installation problems for this type of pile and typical remedial measures to address these problems. Finally, the paper illustrates pile design and installation issues with case histories from three recent bridge projects.
This paper presents the results of a pile installation monitoring and performance assessment prog... more This paper presents the results of a pile installation monitoring and performance assessment program for pile foundations supporting 14 piers and 2 abutments of the 1700-ft long bridge crossing over a river in Baltimore, Maryland. Dynamic measurements were conducted during installation and restrike of 16 test piles, one at each support location. The foundation piles were 30-inch diameter, 0.75 inch thick pipe piles at the piers and 24-inch diameter, 0.5 inch thick at the abutments. The piles at the piers were approximately 100 ft long and were designed to carry 260 kips service load with a factor of safety of 2.25. The piles were driven open ended into a variable site stratigraphy containing recent deposits of organic clayey silts near the mud line followed by loose to medium dense sand, with some silt, and then by soil deposits from the Cretaceous period consisting primarily of dense to very dense, poorly- to well graded sands and gravels and cobbles, with occasional seams of very hard to very stiff, low to moderate plasticity silts and clays. This paper presents the approach taken to evaluate the driven index piles and to develop criteria for driving production piles, and provides the Engineer with some data on pile driveability in Cretaceous soils in the Baltimore area, soil set-up effect, and an estimate of pile capacity.
Ballooning oil prices both in the United States and globally have brought alternative energy sour... more Ballooning oil prices both in the United States and globally have brought alternative energy sources including wind energy to the forefront. Offshore wind energy is fast becoming an attractive proposition because there are vast wind resources located offshore with little visual or noise impact to local communities. But developing these wind resources 15 to 30 km from shore would require large foundations which could be cost prohibitive. To make such a proposition cost effective requires even larger wind turbines. These large wind turbines will place large demands on the support structures and foundations. As an increasing number of wind farms are being planned offshore in water depths of over 50 m, the combination of water depth and the increased windmill tower heights and rotor blade diameters will create loads that make foundation design very complex. Moreover, offshore foundations are exposed to additional loads such as ocean currents, storm wave loading, ice loads and potential ...
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