Pile-deck Connections Research Articles

Analysis of seismic damage mitigation for a pile-supported wharf structure

This paper evaluates earthquake-induced permanent ground deformations and the structural response of a typical pile-supported wharf structure built over loose granular fill. Using numerical simulations for a suite of 55 reference seismic ground motions, we investigate the effectiveness of an array of PV drains installed behind the pile-supported deck in mitigating structural damage associated with deformations of the fill. Numerical analyses use a sub-structuring approach in which the ‘free-field’ 2D coupled deformations, and seepage within the soil fill are simulated using the u-p formulation in the OpenSees finite element framework. The complex non-linear and inelastic stress-strain properties of the sand under cyclic loading are represented using the Dafalias-Manzari (DM2004) bounding surface plasticity model, while customized 1-D finite elements are used to describe flow in the PV drains. The resulting ground deformations and excess pore water pressures are treated as boundary conditions in modeling the response of the wharf structure, through macro-elements that represent local pile-soil interactions (after Varun and Assimaki, 2012 [1]). We discuss the associated soil behavior and show how lateral spreading is mitigated by the proposed PV drain array. This mitigation system limits the potential damage to the pile-deck connections enabling much simpler structural retrofit for the wharf.

Cyclic Nonlinear Behavior of Pile-Deck Connections Using Structural Software Models

A study of the cyclic nonlinear behavior of a pile-deck connection (characteristic of cargo port structures) is performed using OpenSEES Concrete02 and Concrete07. Advantages and disadvantages are determined by comparison with experimental results obtained in previous works. The parameters considered are: hysteretic energy, secant modulus, and ductility at moderate and severe damage. This work seeks to define whether more complex calculations warrant additional runtime. It is found that Concrete07, in fact, is much closer to the experimental results in terms of ductility. However, the estimates of hysteretic energy and secant modulus are similar in both models. A better vulnerability estimate would be obtained based on more accurate parameters such as ductility, hysteretic energy and secant modulus.

Analytical Modeling and Damage Assessment of Shallow Embedment Pile-Deck Connections

This paper presents a simple, yet accurate, approach for analytically describing the nonlinear behavior of shallow embedment pile-deck connections under cyclic loading. The approach is based on incorporating at the pile-deck interface a rotational spring fiber-based element connecting to frame elements where the nonlinearity is distributed along the pile length. This additional element directly takes into account the impacts of the pile's rigid body motion, as well as the interaction between the softening of concrete and slipping of the reinforcement at the end of the pile. Experimental results of four test specimens from the literature are used to calibrate and validate this analytical modeling approach. Comparison between analytical and experimental results shows that the proposed modeling technique is capable of accurately describing the cyclic behavior and damage progression in pile-deck connections.

Three-Dimensional Wharf Response to Far-Field and Impulsive Near-Field Ground Motions in Liquefiable Soils

AbstractSeismic performance evaluation of wharf structures constitutes the core of the vulnerability assessment of seaport infrastructure exposed to seismic events. Because this performance will depend on complex interactions between the surrounding potentially liquefiable soils and wharf foundation and structure, detailed and careful implementation of advanced modeling techniques is needed. These models are required to capture such highly nonlinear phenomena as permanent seaward deformation of embankment soils, soil-structure interaction in liquefiable soils, spread of plasticity in prestressed piles, and force-deformation of pile-deck connections. This study utilizes such modeling approaches to investigate the three-dimensional (3D) nonlinear response of a typical pile-supported container wharf structure in liquefiable embankment soils. Input excitations for this analysis consist of embankment soil deformations for a far-field and an impulsive near-field ground motion. These excitations are derived usin...

Seismic Performance of Pile-Supported Wharf Structures considering Soil-Structure Interaction in Liquefied Soil

Many existing pile-supported marginal wharves within ports along the West Coast of the United States were designed in the late 1960s and early 1970s using the seismic design criteria available then, which were much less robust than the current criteria. As a result, structures designed using these criteria have often been severely damaged during the past earthquakes. This paper investigates the modal properties and vulnerability of such structures by using advanced structural and soil modeling procedures to perform two-dimensional nonlinear plane-strain seismic analyses using time histories of ground displacement and excess pore water pressures within the underlying soil embankment. Results show that the wharf structure experiences large permanent deformations and undergoes failure of the piles and pile-deck connections and pullout of batter piles in tension under large seismic events. Such failures were observed at the Port of Oakland during the 1989 Loma Prieta earthquake and also during other earthquakes throughout the world.

Assessment of Seismic Performance of Two Pile-Deck Wharf Connections

This paper examines the seismic response of two full-scale pile-to-deck connections of marginal wharves built in the 1980s at the Port of Los Angeles. The first test represented a precast pretensioned concrete pile-deck connection at Berth 145. This berth required extending the deck for a new crane rail and a new line of piles. The proposed wharf upgrade considered leaving the existing piles if their lateral displacement capacity exceeded the expected seismic demands. A representative connection was tested to assess the rotation capacity under reversed cyclic loading. The second test represented a typical steel pile-deck connection used in Berth 226. In this structure, the piles support a crane rail. A reversed cyclic loading test was also conducted to assess the connection deformation capacity. Both connections were able to carry the imposed axial load throughout, even when the flexural strength had degraded. The precast pile-deck connection maintained the flexural strength up to a rotation of 0.04 rad, and the steel pile-deck connection maintained its flexural strength up to a rotation of 0.015 rad.

Simplified Procedure for Seismic Evaluation of Piles with Partial-Moment Connection to the Deck in Marine Oil Terminals

This paper presents development of a simplified procedure for seismic evaluation of piles with partial-moment connection typically used in marine oil terminals. The current seismic evaluation procedure of the piles in marine oil terminals includes monitoring material strains specified in the Marine Oil Terminal Engineering and Maintenance Standard (MOTEMS) during the nonlinear static pushover analysis to estimate the displacement capacity of piles. This investigation developed closed-form formulas for estimating the displacement capacity of piles by using a simple pile-deck connection system. The displacement capacity estimated from these formulas ensures that the material stain limits specified in the MOTEMS is not exceeded. These formulas are demonstrated to be accurate by comparing results from these formulas against those from the nonlinear finite-element analysis. The formulas developed in this investigation utilize the curvature ductility capacity of the pile section and rotation ductility capacity of the connection at the selected seismic design level, along with the parameter β which depends on the relative stiffness of the pile and the connection and the parameter η which depends on the relative strength of the connection and the pile.