Search

Past seismic events have shown that pile-supported wharves are susceptible to severe damage during earthquakes, and thus it is important to assess the seismic performance of pile-supported wharves. Seismic fragility analysis is recognized as an effective means for seismic performance assessment of infrastructural systems exposed to seismic hazards since it quantifies the probability of seismic damage conditioned on the various ground motion intensity levels. This study systematically investigates the seismic fragility of a large-scale pile-supported wharf at both component and system levels. It is well known that pile-supported wharf is a typical soil-pile-structure system, and the soil-pile-structure interaction will significantly affect its seismic performance. In this regard, a solid-fluid, fully-coupled nonlinear finite element (FE) model is developed for the seismic analysis of this large-scale pile-supported wharf. Additionally, to determine the quantitative seismic demand bounds for different damage states, this study proposes the use of the pushover analysis-based procedure rather than engineering judgment or engineering common sense which is subjective to a degree. Furthermore, the soil permeability is another parameter that may evidently influence seismic fragility of wharf structures, so its influence is also discussed in detail through parametric studies.

The seismic deformation and soil-structure interaction analyses completed to date (i.e., preliminary design) for the project would benefit from more rigorous validation and calibration of the constitutive models and numerical procedures used in future analyses. The results from the Liquefaction Experiments and Analysis Project (LEAP) are expected to benefit future phases of the project (i.e., detailed design).

Considerable three-dimensional (3D) effects are involved in the seismic performance of pile-supported wharves. Such effects include the pile-to-pile interaction mechanisms as dictated by the behavior of the surrounding soil. This interaction might be further affected by potential ground slope settlement/heave, and the constraint of pile connectivity along the relatively rigid wharf deck. In order to capture a number of these salient response characteristics, a 3D finite element (FE) study is conducted herein. The prototype system motivating this study is presented, along with the corresponding numerical details. A realistic multi-layer soil profile is considered, with interbedded relatively soft/stiff strata. Effect of the resulting seismically-induced ground deformation on the pile-supported wharf system is explored. Specific attention is drawn to the noteworthy potential changes in axial force due to variation in pile embedment depth, and the ground slope deformation. The analysis technique as well as the derived insights are of significance to general pile-wharf-ground system configurations.

This study presents a framework for assessing the seismic performance of a pile-supported wharf at different seismic hazard levels. A refined Three-Dimensional (3D) Finite Element (FE) model is conducted using the open-source computational platform OpenSees. The modeling strategies of the refined numerical model are given in detail, including refined modeling of free-field boundaries and soil-pile interaction. Two seismic hazard levels adopted by the design standard for seismic design of piers and wharves (ASCE 2014) are considered, namely, Contingency Level Earthquake (CLE) and Design Earthquake (DE). The seismic performance of the wharf-ground system is systematically explored in the following two aspects. First, the evaluation of seismic performance is based on the time history response for CLE (and DE) motion. Second, the seismic performance is assessed by averaging maximum response for all 28 DE and CLE motions. The results from this study reveal that (i) the seismic response of the wharf-ground system is larger under a DE motion than under a CLE motion; (ii) the pile foundation with a short free length is more vulnerable to damage for both seismic hazard levels; and (iii) the fiber strains of piles are significantly lower than the strain limits in the design standard (ASCE 2014).

Pile-supported wharves may be subjected to severe damage during major earthquakes. As such, efficient strategies for retrofitting wharf systems are needed. In this study, we investigate the seismic performance of a pile-supported wharf retrofitted by the following three conventional slope strengthening strategies: i) improving the ground with a soil-cement mixture, ii) driving pin piles near dike toe, and iii) creating an underwater bulkhead system using sheet piles. Effectiveness of the three retrofit schemes is assessed comprehensively. First, seismic response of the as-built and retrofitted pile-supported wharf is investigated. Subsequently, performance of the retrofit strategies in mitigating the seismic vulnerability is thoroughly investigated by comparing component- and system-level fragility curves. It was found that: (1) overall, the strategies are effective in mitigating the seismic response and in reducing the seismic fragilities of the wharf system; (2) the performance of the retrofit measures varies at the structural component level, as a retrofit measure may have an isolated local negative effect for a certain structural component. In this regard, an appropriate retrofit strategy should be identified based on specifically defined retrofit purposes; and (3) as implemented, the soil-cement mixture performed best (in lowering the system seismic fragility), followed by the pin pile, and lastly the sheet pile.

The Port of Los Angeles (POLA) is upgrading berths 214-220 container wharves, which includes deepening of berths 214-216 to accommodate larger ship sizes up to 13,000 TEUs. The existing wharf was designed for a mudline elevation near the US Pierhead (USPH) line of approximately -45 ft. (-13.7 m) mean lower low water (MLLW). For the wharf upgrade, the mudline elevation is being deepened to -53 ft. (-16.2 m) MLLW near the USPH line. An underwater bulkhead system, approximately 1,500 linear ft. (457 linear m), will be used to support the deepening of mudline elevation. Among various underwater bulkhead systems considered for the wharf deepening, a continuous sheet pile underwater bulkhead was found to be the most cost-effective solution and was used in final design. This paper discusses the geotechnical investigation, site characterization, ground motion, liquefaction, lateral earth pressures, underwater bulkhead design, and construction considerations.

A major project is underway at the Port of Los Angeles (POLA) that proposes to create approximately 35 acres of land and water for a world-class marine research institute. Approximately 2,540 ft of existing wharves at Berths 57-60 will be upgraded in Phase 1. This is the oldest wharf built in San Pedro Bay and the existing wharf and the shed have been designated as “historic.” This designation requires preservation of the exterior appearance of the shed as well as a visible portion of the wharf located above water. Additionally, POLA is located in a highly seismic area and the proposed project allows public access, thereby requiring any upgrades to meet current building codes. Initial evaluations indicate significant improvements are needed to meet current seismic requirements in addition to repairs for the proposed project. This paper discusses the seismic, structural, and geotechnical aspects of the project and compares various upgrade alternatives considered for implementation.

During the magnitude (Mw) 7.7, 1993 Guam earthquake, which caused significant damages to coastal structures throughout the area, X-Ray Wharf in the island showed signs of liquefaction and lateral spreading and seismically induced settlement up to 30 cm. The existing wharf is approximately 450 m long and consists of a combination of steel sheet pile bulkheads with a single level of tie-backs and steel sheet pile bulkheads with relieving platforms. Even though the damage to the wharf was not significant during the 1993 earthquake, it was found that the existing wharf would not meet the current two-level seismic performance criteria per the latest unified facilities criteria, (UFC) 4-152-01 (DoD, 2005, 2012). Among the various concepts evaluated to upgrade the existing wharf, constructing a new wharf in front of the existing wharf was found to be the most effective solution and taken forward for final design. A new sheet pile bulkhead wall approximately 10.7 m away from the existing sheet pile bulkhead will be constructed and the space between the new and old sheet pile bulkheads will be filled with improved granular backfill. Cement deep soil mixing (CDSM) was selected as the most cost-effective ground improvement technique to improve the granular fill and weak foundation materials. Construction of the new wharf is presently under way. The paper discusses the seismic design philosophy, geotechnical field investigation, site characterization, seismic analyses, and ground improvement design in an informative manner useful to practicing engineers.

The U.S. Territory of Guam is located in a seismically active region and has experienced several major earthquakes in the past. The 1993 earthquake, with a moment magnitude of 7.7, caused significant damage throughout the island. During that event, the existing Uniform wharf wall experienced significant seismically induced settlement and lateral spreading. The adjacent Tango wharf also experienced some damage. The damage at Uniform wharf was so great that the wharf became non-operational after the earthquake. Both Uniform and Tango wharves are being upgraded to meet a two-level design earthquake and seismic performance criteria. New king pile-sheet pile systems with tie-rods connected to vertical pile-supported anchor blocks were designed to upgrade the wharves. Backland liquefaction within the immediate zone behind sheet piles is mitigated using a stone-column ground improvement technique. Acceptance of stone column performance was based on frequent verification borings in the field as well as additional laboratory testing. Driven piles were investigated with a dynamic pile analyzer to optimize anchor pile length and develop pile acceptance criteria. The paper focuses on the seismic design philosophy, geotechnical field investigation, site characterization, seismic analyses, and ground improvement design. In addition, the paper also discusses construction challenges and how they were overcome.

Being one of America's premier seaports, the Port of Long Beach has embarked on an ambitious $1.2 billion Middle Harbor Development Program that involves expansion and modernization of two existing container terminals at Pier E and Pier F. As part of Phase 1, Stage 1 of the program, Pier D, which defines the western edge of the development, will be cut back to expand the Slip 3 channel to accommodate navigation of larger vessels. Active oil wells within the Pier D backland need to be protected and operational during construction. The subsurface materials consist of an old buried rock dike that subsided due to oil extraction activities. In order to achieve the maximum width of the Slip 3 channel while constrained by the presence of active oil wells in the backland, the Pier D cut had to be inclined at 1.6H:1V (horizontal : vertical) which is much steeper than typical submerged slope cuts. The steeper slope cut required a new secant pile wall as well as some form of ground improvement to soils below the rock dike and in areas outside the rock dike prior to dredging to ensure stability of the slope and to protect backland facilities. Due to the presence of the buried rock dike, jet grouting was chosen as the most practical and cost-effective option among the various available ground improvement techniques. This paper discusses the geotechnical investigation and site characterization associated with the design of the jet grouting improvement. This paper also presents the controlling jet grouting parameters developed from the test sections prior to production, the quality control monitoring, and the challenges faced during construction and how they were addressed to successfully complete construction of jet grout columns.

The Port of Los Angeles (POLA) commissioned a project to design and construct a deep-water Crude Oil Marine Terminal (COMT) to accommodate large and small oil tankers and barges. The proposed COMT will be the first deep-water oil terminal to be constructed in California since 1984. The marine structures were designed according to the Chapter 31F of the 2007 California Building Code (CBC 2007), otherwise known as MOTEMS (Marine Oil Terminal Engineering and Maintenance Standards). The project is located in a high seismic region. MOTEMS requires a two- level seismic design with corresponding performance criteria. In addition, the structures were also checked for the CBC 2007 building ground motion criteria. The subsurface materials were found to consist primarily of elastic silt with some clay and sand and also strong but localized thin layers of rock that were encountered at random depths. Several site factors, including the presence and randomness of the hard rock layers and deep waters at the proposed structure locations limited the potential foundation types that were considered suitable for the project. The design of foundations for various structures was further challenged by the high breasting, berthing, and mooring loads from the oil tankers and high seismic loads on the foundations for the unloading platform and trestles. Among the various foundation types evaluated, large-diameter steel pipe piles were considered the most preferred foundation option based on the cost and constructability. This paper addresses the geotechnical challenges associated with the project and measures that were taken to overcome these challenges during development of the project. Copyright 2010 ASCE.

The Berths 136-147 Container Terminal is located in the north and eastern portions of the West Basin of the Port of Los Angeles (POLA) and was built in the 1980's. The proposed project is to expand and modernize the container terminal at Berths 145-147 and upgrade the existing wharf facilities in order to increase capacity from the current (2003) level of approximately 0.9 million 20-foot (6.1 meter) equivalent units (TEUs) of containerized cargo. Major construction elements include dredging, wharf upgrades, installation of an underwater bulkhead, and development of a landside buffer with the surrounding community. A significant feature of design was testing of a representative pile to deck connection simulating existing conditions, in order to evaluate performance under the design seismic event. Upon completion of construction, new 100-foot (30.5 meter) gauge container cranes will be installed at the terminal. At full operation, expected by 2025, the upgraded terminal will handle approximately 2.4 million TEUs per year. This paper addresses the design and construction challenges of the Berths 145-147 wharf upgrade project. Copyright 2010 ASCE.

The Port of Los Angeles (POLA) is a major seaport serving as a "Gateway to the Pacific" both to the Southern California region and nation. The Port has eight liquid bulk facilities comprising a total of 114 acres to handle various types of commodities for both import and export. Handling facilities include tankers, barges, bulk carriers and storage tanks with convenient rail access. The Marine Oil Terminal Engineering and Maintenance Standards (MOTEMS) were approved by the California Building Standards Commission on January 19, 2005, and are codified as Chapter 31F (Marine Oil Terminals), Title 24, California Code of Regulations, Part 2, California Building Code. These standards apply to all existing and new marine oil terminals in California, and include criteria for inspection, structural analysis and design, mooring and berthing, geotechnical considerations, fire, piping, mechanical and electrical systems. Chapter 31F was published by the Building Standards Commission on August 10, 2005 and became effective on February 6, 2006. The POLA developed MOTEMS Program to audit the eight liquid bulk facilities located within the Port of Los Angeles including: 1) Berths 70-71 terminal operated by Westway, 2) Berths 118-120 terminal operated by Kinder Morgan, 3) Berths 148- 151 terminal operated by Conoco-Phillips, 4) Berth 163 terminal operated by Shore Terminals LLC, 5) Berths 164 terminal operated by Ultramar, Inc., 6) Berths 167-169 terminal operated by Shell Oil, 7) Berths 187-191 terminal operated by Vopak, and 8) Berths 239-240C terminal operated by Exxon-Mobil. This paper addresses the audit and design challenges of the POLA MOTEMS program including the preparation of the Initial Audit Report for each facility, and the preparation of Plans, Specifications, and Estimates (PS&E's) to bring the identified facilities into compliance with MOTEMS standards. Copyright 2010 ASCE.

ii ACKNOWLEDGEMENTS ii TABLE OF CONTENTS iii LIST OF SYMBOLS vi LIST OF FIGURES ix LIST OF TABLES xii CHAPTER

The Port of Long Beach (POLB) acknowledged in the late 1990's that the continuous increase in container throughput volume would require establishing a consistent system of standards and guidelines for the design of container wharves to successfully execute the necessary capital improvement. The understanding of seismic requirements for design of pile-supported wharves has considerably increased during recent years. New and larger ships provided new challenges; new details and practices for the design and construction of wharves were developed and followed by new codes and guidelines for port structures. This work, however, was driven by different authorities, often not closely coordinated: Code Writing Authorities, Owners (Ports), and Consultants. As a result of the rapid development in this field, the resulting documents for the seismic design of wharves made their interpretation sometimes difficult. POLB recognized the need for uniform and port-specific guidelines and developed port specific Wharf Design Criteria. This paper specifically addresses the Seismic Design Criteria. They include Ground Motions and Performance Criteria, Geotechnical Considerations with particular attention to soil-structure interaction, Structural Design and Analysis Methods, and Seismic Detailing. These subjects are specifically adjusted for site-specific conditions in POLB, such as seismicity, foundation soils, construction practices and the requirements of the Port's Engineering Bureau, which had an important function in the development of the criteria. All seismic design and analysis procedures are based on displacement-based procedures. The development of the criteria was reviewed at various stages by experts in structural, geotechnical, and earthquake engineering disciplines. An experimental program verified the analytical assumptions. POLB's recent wharf construction experience confirmed the practicality of the construction details. It is anticipated that these Criteria will provide more uniformity, focus on design, quality assurance, and minimize construction costs, while providing better coordination between POLB's engineering staff and consultants.

Guam has experienced several large earthquakes in the past several decades. The 1993 earthquake with a moment magnitude of 7.7 caused significant damage throughout the island. Liquefaction and lateral spreading caused damages to commercial and naval port facilities at Apra Harbor. The Alpha-Bravo wharf, built in 1947 without proper seismic considerations, suffered some damage during the 1993 earthquake, including backland liquefaction. The U.S Navy commissioned a seismic improvement program that included upgrade of the Alpha-bravo wharf. The improvements to the wharf included increasing the water depth from approximately 10.7 m to 12.8 m, and retrofitting the existing wharf to meet current seismic and future operational requirements. A two-level seismic performance criterion was used: under the Level 1 earthquake associated with a 72-year return period, wharf elements sustain only minor or no structural damages with no interruption to operations; under the Lever 2 earthquake events with 475-year return period, the wharf elements undergo controlled inelastic structural behavior with repairable damage. Sheet piles and tie-back system were designed to accomplish the seismic retrofit and improvement of the wharf. In order to withstand high tie-back forces, the anchor blocks in the backlands were supported on battered, steel H piles. During construction, the test piles driven at anchor blocks showed softer driving, and dynamic pile analyses results indicated lower axial capacities than the design capacities. Adjustments were made by adding lugs to piles and increasing pile lengths to incorporate the findings from test piles. Partnering meetings and proactive participation of all interested parties including the owner, designers, and contractor throughout the construction of the project helped minimize project delays and cost overruns.

This paper discusses the Seismic Engineering Program that has been developed at the Port of Los Angeles (POLA). Over the years, experts have collaborated with POLA staff in a continuous effort to develop a modern seismic code for container wharves. Since 1990, several workshops have been conducted and many documents and technical papers have been published. The current code, “The POLA Code for Seismic Design, Upgrade and Repair of Container Wharves” (POLA, 2004), emphasizes performance-based design and soil-structure interaction to reflect the challenges of designing container wharf structures in an active fault region of Southern California. A Technical Advisory Board consisting of experts in structural and geotechnical earthquake engineering disciplines has reviewed the development of the code at all stages. Recent wharf construction at the Port confirmed the practicality of the design procedure and construction details. In addition, the Port sponsored and funded an experimental program at the University of California at San Diego to confirm code assumptions. A Port-wide ground-motion and fault study program was undertaken to develop uniform seismic ground motion hazards for the entire Port to augment the Port’s future projects and develop more consistent designs. At the time of writing this paper, POLA is in the process of preparing a book to present its efforts on seismic code development of container wharves. It is hoped that this comprehensive seismic engineering program will provide useful information to other port agencies and the marine design industry both nationally and internationally.

The Port of Los Angeles (POLA) and Port of Long Beach (POLB) jointly embarked on a ground motion study of the Los Angeles-Long Beach harbor area to develop consistent seismic ground motion recommendations for design of structures within the ports. Regional and site geology and seismicity were reviewed to establish the latest understanding on geological features and faults contributing to the seismic hazard at the POLA and POLB, with particular attention on the Palos Verdes fault, a major fault in the region that passes directly through the POLA area, and the nearby Newport-Inglewood fault. Ground conditions affecting site response were interpreted from borehole and geophysical data available in existing geotechnical reports for both ports. Probabilistic seismic hazard analyses were performed using latest revisions of ground-attenuation models commonly used in California, including the latest version of an attenuation model that is being developed as part of the Pacific Earthquake Engineering Research/Lifelines Next Generation Attenuation Project. Adjustments for near-fault rupturing effects were made and uncertainties in earthquake source and attenuation model parameters were addressed through the use of logic trees. Local site conditions were incorporated based on quantitative and qualitative assessment and supported by empirical strong motion data. Horizontal and vertical-component uniform hazard spectra for design events were developed for various damping values and seven sets of spectrum-compatible acceleration-time histories were also developed.

A section of the existing wharf and reclamation of the Kings Wharf in Suva, Fiji has been selected for an upgrade to serve as a lifetime wharf in the event of an earthquake. The reclamation is retained by a 16 m deep sheet pile wall, tied back near the top and supported at the toe by a rock bund. The wharf deck is supported on 760 mm diameter prestressed hollow core piles and is connected to the reclamation by a series of bridging decks. The geology consists of a large depth (40 m) of soft soils. With excessive horizontal movements known to have occurred during construction, and with the knowledge of marginal stability from limiting equilibrium slope stability analyses, more sophisticated modeling was applied to better understand the stability concerns. The finite difference computer program FLAC was selected for this purpose. The objectives were to asses the stability of the existing wharf configuration under both static and seismic loading, and evaluate a proposed soil-cement improvement. The cement treatment is applied to a soil block 30-40 m deep and 14.5 m wide, immediately behind the existing sheet piles. The FLAC analyses showed that the cement treated block did not address the deep-seated stability problem. However this also highlighted the effects of shallower movements in the rock toe bund causing structural distress to the piles. The soil-cement improvement was a necessary rehabilitation measure for limiting the displacements in the deep soft soils. Additional measures (reduction in rock bund height and infilling the hollow core piles) to address more structurally orientated shortcomings were also necessary.