Probabilistic Analysis of Live Loads on Offshore Platform Piles

2005 ◽  
Author(s):  
Hassan Zaghloul ◽  
Beverley Ronalds ◽  
Geoff Cole
Keyword(s):  
Probabilistic Analysis ◽  
Field Measurements ◽  
Weather Conditions ◽  
Load Resistance ◽  
Live Load ◽  
Offshore Platforms ◽  
Open Area ◽  
Foundation Design ◽  
Live Loads ◽  
Load Intensity

Relatively accurate techniques are available to assess structural behavior under given loads, yet the loads themselves remain an estimate based in part on field measurements, in part on professional logic and experience, and in part on trial and error. The design of piled foundations for fixed offshore platforms must consider operating and extreme weather conditions. In the operating condition, the magnitude of live loads on open areas of topside structure is an important consideration. Unfortunately, the design live load intensity that applies to open areas on offshore platforms is not identified in international codes and standards. There does not appear to be any consensus on the value to be adopted in the industry. Some operators suggest the open area live loads need not be considered for pile foundation design, while others stipulate values such as 10 kPa. This is partly due to the variability associated with the different live loads sources. The objective of this study is to obtain a better understanding of open area live loads on offshore platforms and develop a methodology to obtain the long-term and extreme open area live load. A load survey was conducted for the purpose of this study, and a probabilistic analysis was carried out to derive the maximum axial load on piles that is expected during platform lifetime. The results of this study indicate that the use of a single value for the open area live load (OALL) may not be appropriate and suggest appropriate values for Load Resistance Factor Design (LRFD) or Working Stress Design (WSD) methods.

Monitoring of the Response of the Sagamore Parkway Bridge and its Foundations During a Live Load Test

2020 ◽  
pp. 036119812097126
Author(s):  
Fei Han ◽  
Mehdi Marashi ◽  
Monica Prezzi ◽  
Rodrigo Salgado ◽  
Timothy Wells ◽  
...  
Keyword(s):  
Pile Group ◽  
Bridge Pier ◽  
Load Test ◽  
Live Load ◽  
Foundation Design ◽  
Pile Cap ◽  
Live Loads ◽  
The Individual ◽  
Bridge Foundation ◽  
Live Load Test

In this paper, we report the results of a live load test performed on the Sagamore Parkway bridge over the Wabash River, Indiana. The seven-span concrete bridge was constructed from 2016 to 2018 to replace the old, east-bound bridge. The main goals of the live load test were: (i) to study the transfer of the live loads from the bridge pier to the foundation elements and the distribution of live loads among the individual piles supporting the bridge pier; and (ii) to verify the assumptions (e.g., regarding the pile cap resistance) made in bridge foundation design. For these purposes, one of the interior piers (Pier 7) of the bridge and the fifteen pipe piles supporting it were instrumented with vibrating-wire strain gauges. With the bridge temporarily closed to traffic, the live load test was performed by parking twelve loaded triaxle trucks at specific locations on the bridge deck near Pier 7 in March 2019. The truck loads were applied in seven stages, simulating the driving of several trucks over the bridge pier. The settlement of the pier was measured using a digital level during the live load test. The data from the strain gauge readings were processed to produce the history of load distribution within the cross section of the pier and among the piles in the pile group during the seven stages of the live load test. The soil in contact with the pile cap carried about half of the total live load.

scholarly journals Canadian highway bridge evaluation: load and resistance factors

1992 ◽  
Vol 19 (6) ◽  
pp. 992-1006 ◽  
Author(s):  
D. J. Laurie Kennedy ◽  
Darrel P. Gagnon ◽  
David E. Allen ◽  
James G. MacGregor
Keyword(s):  
Field Measurements ◽  
Highway Bridges ◽  
Live Load ◽  
Safety Criterion ◽  
Transverse Distribution ◽  
Resistance Factors ◽  
Load Factors ◽  
Target Values ◽  
Load And Resistance Factors ◽  
Live Loads

Consistent load and resistance factors are developed for a range of target values of the reliability index, β, following first-order second-moment analysis techniques for use in the evaluation of highway bridges. Dead load factors are established for steel girders, concrete girders, concrete bridge decks, and wearing surfaces, taking into account the statistical variations of weights and the range of load fractions as determined from field measurements. Live load factors are established for four categories of live loads: NP — non-permit traffic that are permitted by legislation; PM — permit, multiple trip, bulk haul, divisible loads; PS — permit, single trip, unsupervised, mixed with non-permit traffic; and PC — permit, controlled, supervised extremely heavy loads with escort. These live load factors are based on field surveys of truck weights, in Alberta and elsewhere. The event curves for NP, PS, and PM traffic have been used to determine the maximum annual truck, as the period of evaluation was chosen as 1 year based on a life-safety criterion-related to the consequences of failure. Because PC traffic is so rare, it was dealt with on an event basis. Impact data of others were analyzed to determine the appropriate bias coefficients and coefficients of variation. Uncertainties in the transverse distribution of both dead and live loads were also considered.Resistance factors are based on statistical data reported in the literature and take into account the variation in material properties, member size, and the resistance formulations. Key words: dead and live load factors, resistance factors, impact, maximum annual, traffic categories, transverse distribution, weight fractions.

Sediment transport under dry weather conditions in a small sewer system

1998 ◽  
Vol 37 (1) ◽  
pp. 155-162
Author(s):  
Flemming Schlütter ◽  
Kjeld Schaarup-Jensen
Keyword(s):  
Sediment Transport ◽  
Field Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sewer System ◽  
Transport Models ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Initial Results

Increased knowledge of the processes which govern the transport of solids in sewers is necessary in order to develop more reliable and applicable sediment transport models for sewer systems. Proper validation of these are essential. For that purpose thorough field measurements are imperative. This paper renders initial results obtained in an ongoing case study of a Danish combined sewer system in Frejlev, a small town southwest of Aalborg, Denmark. Field data are presented concerning estimation of the sediment transport during dry weather. Finally, considerations on how to approach numerical modelling is made based on numerical simulations using MOUSE TRAP (DHI 1993).

Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

2021 ◽  
Author(s):  
Julie Paprocki ◽  
Nina Stark ◽  
Hans C Graber ◽  
Heidi Wadman ◽  
Jesse E McNinch
Keyword(s):  
Moisture Content ◽  
Laboratory Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sandy Beaches ◽  
Percent Error ◽  
Moisture Contents ◽  
Multispectral Satellite Imagery ◽  
Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

Simplified Method for Time-Dependent Reliability Analysis of Aging Bridges Subjected to Nonstationary Loads

2016 ◽  
Vol 23 (01) ◽  
pp. 1650003
Author(s):  
Cao Wang ◽  
Quanwang Li
Keyword(s):  
Structural Reliability ◽  
Operating Conditions ◽  
Time Dependent ◽  
Structural Resistance ◽  
Simplified Method ◽  
Increasing Trend ◽  
Live Loads ◽  
Load Intensity ◽  
Existing Bridges ◽  
Dimensional Integral

The performance of existing bridges may deteriorate in time due to aggressive environmental or operating conditions in service, which may eventually cause changes in structural resistance and reliability beyond the baseline assumed for new ones. In addition, the increasing trend of live loads applied to the bridges, which has been reported in many researches, also contributes to the reduction of structural reliability. In order to perform time-dependent reliability assessment for aging bridges subjected to nonstationary loading process with improved efficiency, a simplified method is proposed in this paper, where lower dimensional integral is involved in the calculation of reliability. With the proposed method, time-dependent reliability of a real aging RC bridge is conducted, and the effect of nonstationarity in load intensity on structural reliability is investigated. It is found that structural reliability is sensitive to the increase of load intensity, and is less sensitive to the varying mechanism of load intensity.

Superstructure–foundation interaction in multi-objective pile group optimization considering settlement response

2017 ◽  
Vol 54 (10) ◽  
pp. 1408-1420 ◽  
Author(s):  
Y.F. Leung ◽  
A. Klar ◽  
K. Soga ◽  
N.A. Hoult
Keyword(s):  
Shear Walls ◽  
Field Measurements ◽  
Pile Group ◽  
Optimization Approach ◽  
Full Potential ◽  
Foundation Design ◽  
Soft Storey ◽  
Multi Objective ◽  
Piled Raft ◽  
First Case

The full potential of pile optimization has not been realized as the interactions between superstructures and foundations, and the relationships between material usage and foundation performance are rarely investigated. This paper introduces an analysis and optimization approach for pile group and piled raft foundations, which allows coupling of superstructure stiffness with the foundation model, through a condensed matrix representing the flexural characteristics of the superstructure. This coupled approach is implemented within a multi-objective optimization algorithm, capable of providing a series of optimized pile configurations at various amounts of material. The approach is illustrated through two case studies. The first case involves evaluation of the coupled superstructure–foundation analyses against field measurements of a piled raft–supported building in London, UK. The potential benefits of pile optimization are also demonstrated through re-analyses of the foundation by the proposed optimization approach. In the second case, the effects of a soft storey on the superstructure–foundation interactions are investigated. These cases demonstrate the importance of properly considering the superstructure effects, especially when the building consists of stiff components such as concrete shear walls. The proposed approach also allows engineers to make informed decisions on the foundation design, depending on the specific project finances and performance requirements.

scholarly journals Reliability-Based Safety Evaluation of the BISTOON Historic Masonry Arch Bridge

2020 ◽  
Vol 30 (1) ◽  
pp. 87-110 ◽  
Author(s):  
Majid Pouraminian ◽  
Somayyeh Pourbakhshian ◽  
Ehsan Noroozinejad Farsangi ◽  
Sevil Berenji ◽  
Salman Keyani Borujeni ◽  
...  
Keyword(s):  
Probabilistic Analysis ◽  
Safety Evaluation ◽  
Random Variables ◽  
Load Resistance ◽  
Maximum Tensile Stress ◽  
Safety Index ◽  
Limit States ◽  
Masonry Arch ◽  
Arch Bridge ◽  
Historic Masonry

AbstractThis research examines the probabilistic safety assessment of the historic BISTOON arch bridge. Probabilistic analysis based on the Load-Resistance model was performed. The evaluation of implicit functions of load and resistance was performed by the finite element method, and the Monte-Carlo approach was used for experiment simulation. The sampling method used was Latin Hypercube. Four random variables were considered including modulus of elasticity of brick and infilled materials and the specific mass of brick and infilled materials. The normal distribution was used to express the statistical properties of the random variables. The coefficient of variation was defined as 10%. Linear behavior was assumed for the bridge materials. Three output parameters of maximum bridge displacement, maximum tensile stress, and minimum compressive stress were assigned as structural limit states. A sensitivity analysis for probabilistic analysis was performed using the Spearman ranking method. The results showed that the sensitivity of output parameters to infilled density changes is high. The results also indicated that the system probability of failure is equal to p fsystem =1.55 × 10−3. The bridge safety index value obtained is βt = 2.96, which is lower than the recommended target safety index. The required safety parameters for the bridge have not been met and the bridge is at the risk of failure.

Structural Behavior of Three-Sided Arch Span Bridge

1996 ◽  
Vol 1541 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Timothy J. McGrath ◽  
Ernest T. Selig ◽  
Timothy J. Beach
Keyword(s):  
Structural Design ◽  
Load Test ◽  
Structural Performance ◽  
Live Load ◽  
Element Analysis ◽  
Annual Basis ◽  
Soil Stress ◽  
Load Effects ◽  
Live Loads ◽  
Adjacent Segments

A study was undertaken to evaluate the methodology used for the structural design of three-sided culverts with arched top slabs. An 11-m span by 3.4-m rise bridge was instrumented and monitored during installation, under an HS-25 + 30 percent live load and at 6-month intervals for 2 years after installation. The bridge consisted of ten 1.6-m-wide precast segments. Three of the interior segments were instrumented with soil stress cells mounted on the legs of the bridge and with anchor pins for use with a tape extensometer to determine change in shape of the bridge. Survey data were taken on the same three segments and the two adjacent segments. Visual observations were also made to monitor cracking. The live load test was conducted with 0.3 m of cover. Final cover was 0.9 m. The bridge showed less movement under the live load than under the 0.9 m of earth load. The 2-year data show that the shape of the bridge and the soil stresses at the sides of the bridge cycle on an annual basis and that the spans have increased 4 to 8 mm over the 2 years since the completion of construction and appear to be still increasing. Overall, the structural performance of the bridge under earth and live loads was excellent. The correlation between the measured behavior and the computer analysis was good except that the actual live load effects were much smaller than assumed for design. The results of the project support the use of finite-element analysis to design such structures.

scholarly journals Estimation of Individual Exposure to Erythemal Weighted UVR by Multi-Sensor Measurements and Integral Calculation

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4068
Author(s):  
Wenwen Cheng ◽  
Robert Brown ◽  
David Vernez ◽  
Daniel Goldberg
Keyword(s):  
Mean Squared Error ◽  
Field Measurements ◽  
Open Area ◽  
High Agreement ◽  
Individual Level ◽  
North East ◽  
Squared Error ◽  
Effective Interventions ◽  
Adult Model ◽  
Sky Conditions

Ultraviolet radiation (UVR) can be hazardous to humans, especially children, and is associated with sunburn, melanoma, and the risk of skin cancer. Understanding and estimating adults’ and children’s UVR exposure is critical to the design of effective interventions and the production of healthy UVR environments. Currently, there are limitations to the ways computer modeling and field measurements estimate individual UVR exposure in a given landscape. To address these limitations, this study developed an approach of integral calculation using six-directional (up, down, south, north, east, and west) field-measured UVR data and the estimated body exposure ratios (ER) for both children and adults. This approach showed high agreement when compared to a validated approach using ambient UVR and estimated ER data with a high r-square value (90.72% for child and adult models), and a low mean squared error (6.0% for child model and 5.1% for adult model) in an open area. This approach acting as a complementary tool between the climatology level and individual level can be used to estimate individual UVR exposure in a landscape with a complicated shady environment. In addition, measuring daily UVR data from six directions under open sky conditions confirmed that personal dosimeters underestimate actual individual UVR exposure.

Minimizing Fatigue and Fracture in Steel Bridges

1980 ◽  
Vol 102 (1) ◽  
pp. 20-25 ◽  
Author(s):  
J. W. Fisher ◽  
B. T. Yen ◽  
K. H. Frank
Keyword(s):  
Laboratory Tests ◽  
Field Data ◽  
Steel Bridges ◽  
Range Limits ◽  
Live Load ◽  
Stress Range ◽  
Fatigue And Fracture ◽  
Live Loads ◽  
Material Fracture ◽  
Initiation Stage

Steel bridges are subjected to live loads which produce variable stress ranges in bridge components. At welded bridge details, the existence of initial defects and residual stresses eliminate the initiation stage of fatigue crack growth, and stress range is found to be the controlling factor for crack propagation. Laboratory tests have resulted in stress range-fatigue life relationships for various bridge details. These data correlate well with fracture mechanics theory and with field data. Limits on live load stresses have been adopted for steel bridges. Coupled with material fracture toughness requirements, the stress range limits minimize the probability of fatigue and fracture in steel bridges.

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