COUPLED P-Y T-Z ANALYSIS OF SINGLE PILES IN COHESIONLESS SOIL UNDER VERTICAL AND/OR HORIZONTAL GROUND MOTION

Various approaches are currently used for the analysis of piles under vertical and lateral loading. Among these, the beam-on-a-nonlinear Winkler foundation (BNWF) approach using published P-y, T-z and Q-z curves is widely used in practice. In this approach, the P-y and T-z responses are generally uncoupled from each other. The objective of this paper is to investigate the influence that the coupling of the P-y and T-z responses has.on the cyclic and dynamic response of piles in cohesionless soil. A cyclic model is first developed and a parametric study is conducted to investigate the effect the initial confining pressure, angle of wall friction and effective vertical stiffness have on the lateral cyclic hysteretic response. A dynamic model is then developed, and used to study the response of a single pile in cohesionless soil under horizontal and/or vertical ground motion. Results from the parametric study showed that the three parameters did not have a significant influence on the lateral cyclic hysteretic response. Under horizontal and/or vertical ground motion, the horizontal ground motion was observed to dominate the inertial interaction response, and significantly affected both the horizontal and vertical displacement response, mainly due to second-order P-Δ and gapping effects.     

Effect of Shaft Diameter of Pile on Lateral Winkler Springs' Stiffness

Soil was modelled with linearly elastic three-dimensional finite elements. Lateral spring stiffness was calculated from FE results. Spring stiffness is shown varying linearly with shaft diameter. It is also found that spring stiffness is inversely proportional to powers (less than unity) of pile flexural rigidity. Scaling factors for shaft diameter and pile flexural rigidity are introduced. Basic stiffness of lateral spring is studied considering both full vertical slippage and zero slippage between the soil and the pile. Relevant relationships for stiffness are proposed. Some applications are suggested.     

Investigating the Impact of Concrete Driven Piles on the Archaeological Record Using Soil Micromorphology: Three Case Studies from the Netherlands

Abstract

In this paper we present the results of field tests into the impact of driven concrete piles on three archaeological sites in the Netherlands. The field tests were done in two different types of archaeological sites. Two locations in the northern part of the Netherlands (Kenwerd and Groot Wetsinge) were artificial mounds or terps, where new buildings were going to be constructed using driven piles. The third location was Voorburg in the western part of the country, where the impact of pilings from the 1950s were studied. We analysed soil which was in direct contact with the piles, and soil at a distance from the pile surface.

The tests show remarkable results. Visible effects of piling in sand were downdrag of sediments along with the pile, disturbance of structure by local displacements, or liquefaction. In clay, some disturbance of structure, compression of pores, and damage to carbonized material was observed. Additionally, piles may promote the formation of pyrite in the directly adjacent peat. In a large number of samples taken from soil directly adjacent to a pile, no disturbance was observed. We did not observe any impact further than six to eight cm from the pile surface.

These results indicate that the impact of piling in fine sediments is smaller than is generally assumed. However, as the number of observations in the present study is relatively small, the results need to be corroborated by more field tests. In future, planners need to consider the direct effects piles have on the surrounding soil as well as the possibility of excavations.     

Seismic Behavior of L-Shaped RC Squat Walls under Various Lateral Loading Directions

Considerable progress has been made on the research of non-rectangular reinforced concrete (RC) squat walls over the past decades. However, the experimental data of L-shaped RC squat walls remain limited, especially for their seismic behaviors under non-principal bending actions. This paper presents an experimental and numerical investigation on L-shaped RC squat structural walls with an emphasis on how varying the directions of lateral cyclic loading influences the seismic responses of these walls. Four L-shaped specimens are tested under lateral cyclic displacements and low levels of axial compression The variables are axial loads and lateral loading directions. The performance of specimens is discussed in terms of cracking patterns, failure mechanisms, hysteretic responses, deformation components and strain profiles. Furthermore, three-dimensional finite element models are developed to supplement the experimental results. The direction of lateral loading is found to have a significant effect on the peak shear strength of L-shaped RC squat walls.     

Effect on the Structure in Elevation of Wood Deterioration on Small-Pile Foundation: Numerical Analyses

Wooden pile foundations are quite common in Venice historical building. Very short, small-diameter piles are embedded into the soft shallowest soil layer under the groundwater level, but wood degradation is not prevented as anaerobic bacteria can flourish even in anoxic condition. This study couples the behavior of the masonry structure and the foundation as result of pile degradation. The numerical analyses, relative to the ancient piling, consider wood decay and secondary settlement of soil. The effect of deterioration as a function of the pile spacing and the possible presence of a stiff layer under pile tips are also investigated. The geotechnical results are then used as input for the structural model. The behavior of the masonry as result of different states of wood conservation along the wall is studied numerically.     

SIMPLE EXPRESSION OF THE DYNAMIC STIFFNESS OF GROUPED PILES IN SWAY MOTION

A simplified expression is derived for the dynamic stiffness of grouped piles subjected to lateral loading. A computer program, based on the Thin Layered Element Method, is used for this purpose. The results of the program are compared with rigorous solutions. The simplified expression of the dynamic stiffness of grouped piles, where the mass, damping and stiffness parameters are frequency invariant, will be particularly useful for an equivalent linear analysis of the interaction between nonlinear soil and grouped piles in real time.     

Displacement Ductility Limits for Pile Foundations in Cohesionless Soils

The displacement ductility limit for seismic design of concrete piles is determined for the range of cohesionless soils expected in practice. The curvature ductility capacity associated with specified performance limit states, namely, the “serviceability” and “damage-control” limits, is determined based on the current provisions for confining steel. An analytical model is applied to assess the displacement ductility factor at the specified curvature ductility level. The investigated parameters include the soil stiffness, pile diameter, longitudinal reinforcement ratio, axial force level, and pile above-ground height. A set of design displacement ductility factors is recommended and verified to ensure the satisfactory seismic performance.     

Probabilistic Seismic Design of Pile Foundations in Non Liquefiable Soil by Response Spectrum Approach

The behavior of pile foundations in non liquefiable soil under seismic loading is considerably influenced by the variability in the soil and seismic design parameters. Hence, probabilistic models for the assessment of seismic pile design are necessary. Deformation of pile foundation in non liquefiable soil is dominated by inertial force from superstructure. The present study considers a pseudo-static approach based on code specified design response spectra. The response of the pile is determined by equivalent cantilever approach. The soil medium is modeled as a one-dimensional random field along the depth. The variability associated with undrained shear strength, design response spectrum ordinate, and superstructure mass is taken into consideration. Monte Carlo simulation technique is adopted to determine the probability of failure and reliability indices based on pile failure modes, namely exceedance of lateral displacement limit and moment capacity. A reliability-based design approach for the free head pile under seismic force is suggested that enables a rational choice of pile design parameters.     

A Late Roman Quay in the River Meuse near Cuijk,Netherlands

The detection of the waterlogged remains of massive oak foundation piles in the river Meuse near the Dutch city of Cuijk led to the discovery of a unique Late Roman site. The piles, driven into the river‐bed, had protected vast layers of organic material containing all kind of artefacts against erosion by the river. Increased erosion during recent decades has uncovered much of the structure and artefacts, which have been meticulously recorded and collected by divers of the Dutch foundation Mergor in Mosam. Analysis of all data retrieved over the past 20 years has provided much information about the environment and life in Ceuclum, the Roman city of Cuijk.     

Between the Piles. Studying Excavation Photographs to Determine the Area of Physical Disturbance Caused by Piling in the Netherlands

Excavation photographs that show piles can be used to determine and measure the area of disturbance around piles. Until now, this has only been done at a small scale and with ideal examples. The present study shows that less ideal photographs can also be used to determine the disturbance around piles, at a much larger scale. Using predefined methods of documentation and registration, data can be collected about the disturbance of different types of piles, with varied piling techniques, in various burial environments and archaeological contexts. This data will be used in the second phase of the research to determine the loss of archaeological information due to piling.     

Deep Impact: What Happens When Archaeological Sites are Built on?

Abstract

Increasingly, developers and archaeologists search for ways to build on archaeological sites, while at the same time preserving the remains underneath. However, deciding which effects of construction on archaeological sites are acceptable and which are not is hampered by the lack of knowledge on the impacts of construction on archaeological sites. This paper provides an update on some of the effects of building on archaeological sites. Recent research had shown that displacement piles cause less disturbance in soft soils than previously thought. Moreover, replacement piles may be less benign that assumed up till now. Effects of loading on archaeological sites are described, and gaps in the knowledge on these effects are indicated. More research is needed in this field, especially on predicting soil disturbance and damage to weak materials. Impermeable surfaces and constructions on top of sites may affect the visibility of soil features due to decreased rainwater infiltration. Finally, a series of non-physical effects are mentioned that will have to be taken into account when deciding on allowing building on archaeological sites.     

Distribution of Lateral Forces in Base-Isolated Buildings Considering Isolation System Nonlinearity

The ASCE 7 equivalent lateral force method for base-isolated buildings applies a triangular distribution of forces to the superstructure. This distribution attempts to approximately account for the observed effects of isolation system nonlinearity on the superstructure response, but a more rational approximation is needed. Using nonlinear regression analysis of median response data from nonlinear response history analysis of representative systems, improved equations are developed to estimate the lateral force distribution in the superstructure. The ASCE 7 distribution, a revision considered by a SEAONC committee, and the improved distribution developed here are evaluated. Only the improved equations are accurate over many system parameters.     

Investigation of the Optimum Height of Railway Embankments during Earthquake Based on Their Stability in Liquefaction

One of the most reported problems in the railway embankments is loss of their overall stability and major settlements due to liquefaction. Although several studies have been made on the stabilization of embankments, the effects of the influencing parameters on the stability of embankments during liquefaction have not been sufficiently investigated. The series of two dimensional plane strain finite element (FE) models were developed using multi yield surface plasticity model namely Prevost. The results were represented and discussed in terms of foundation excess pore pressure, embankment settlements and their failure modes. By analyzing the results, the optimum height of embankment which minimizes the settlement and failure cracks was derived.     

Gender Bending and Exoticism in Japanese Girls’ Comics

Gender bending has been a staple of the medium of shōjo manga, Japanese girls’ comics, as best exemplified by cross-dressing “girl knight” characters and “Boys Love” stories, whose plots focus on romance between effeminate beautiful young men. The imaginary space created through the representation of these figures shares many traits in common with another typical feature of shōjo comics, namely their exoticisation of Europe. Both have been used as simultaneously escapist and subversive strategies, as a refuge from contemporary social norms and a platform for critical reflection. In this article, I aim to problematise our understanding of the connection between gender bending and exoticism in shōjo manga through an analysis of the representation of one specific aspect of European culture – namely, the Christian religion – in the genre of Boys Love manga.     

Structural Aspects of Medieval Timber Bridges

THIS ARTICLE compares our very fragmentary knowledge of large medieval timber bridges with the respectable body of evidence now available, and here summarized, about bridges at castles and moated sites, which, it is suggested, may be relevant to larger bridges. Nearly all the moat-bridges, from the late nth to the 16th centuries, are structurally similar in that their posts are not earth-fast but tenoned into transverse sole-plates, but the enduring type, with lateral braces, or shores, symmetrically disposed, does not appear until the ijth century. Parallel with these are various specialized forms which are stabilized by additional, longitudinal plates. In the British Isles earth-fast piles were of very limited use in minor bridges but may have become usual in major bridges in the late middle ages.     

Evaluation of IBC Equivalent Static Procedure for Base Shear Distribution of Seismic Isolated Structures

It has been pointed out that the static lateral response procedure for base isolated structures presented in IBC somewhat overestimates the seismic story force [Lashkari and Kircher, 1993 Lashkari, B. and Kircher, C. A. . Evaluation of SEAOC/UBC analysis procedures, Part 1: Stiff superstructure. Proceedings of a Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control. Redwood City, California. ATC Report 17-1.  [Google Scholar]; Constantinou et al., 1993 Constantinou, M. C., Winters, C. W. and Theodossiou, D. . Evaluation of SEAOC and UBC analysis procedures, Part 2: Flexible Superstructure. Proceedings of a Seminar on Seismic Isolation, Passive Energy Dissipation and Active Control. Redwood City, California. ATC Report 17-1.  [Google Scholar]]. In this article IBC equivalent static method for base shear distribution of seismic isolated structures is evaluated. For this purpose one-story to six-story building models are designed according to equivalent lateral response procedure for different elastomeric isolation systems. The results of equivalent lateral response procedure in parameters such as base shear and vertical distribution of base shear are compared with results obtained from dynamic nonlinear analysis and the efficiency and limitations of its application are investigated. In general, the results of equivalent lateral response procedure in base shears are acceptable within the scope of this procedure, but the proposed triangular distribution of base shear is somewhat conservative. So a new formulation for vertical distribution of base shear is proposed which results in a more realistic distribution of shear over the height of isolated buildings. The accuracy of the new formulation is examined by comparing the resulting responses obtained from this study with those calculated by nonlinear time history analysis.     

Study on a Simplified Calculation Method for Hydrodynamic Pressure to Slender Structures Under Earthquakes

Based on Morison hydrodynamic force theory, a simplified calculation method for hydrodynamic force to slender structures is proposed. A typical cylindrical deep water pile was chosen for study and the simplified method was used to analyze the influence of hydrodynamic pressure on the pile. Then the finite element method was used to study the dynamic characteristics of the model, and the results from both methods were compared. A comparison was also made between the shaking table test on the south tower of the Nanjing Yangtze 3rd River Bridge and the results from the simplified method.     

Review of Different Pushover Analysis Methods Applied to Masonry Buildings and Comparison with Nonlinear Dynamic Analysis

This article presents the comparison among different nonlinear seismic analysis methods applied to masonry buildings, i.e., pushover analyses with invariant lateral force distributions, adaptive pushover analysis and nonlinear dynamic analysis. The study focuses on the influence of lateral force distribution on the results of the pushover analysis. Two simple benchmark case studies are considered for the purpose of the research, i.e., a four-wall masonry building prototype without floor rigid diaphragms and a two-wall system with a cross-vault. The comparative study offers a useful review of pushover analysis methods for masonry structures and shows advantages and possible limitations of each approach.     

Selective reburial: a potential approach for the in situ preservation of waterlogged archaeological wood in wetland excavations

Excavations at Dispilio, a prehistoric lakeside settlement in northern Greece, have revealed a significant number of vertical wooden piles that need to be protected during and after excavation. Lifting of the piles is not possible and approaches such as reburial, cannot currently be implemented as excavation is still in progress. In 2005, several posts were “selectively buried” on an experimental basis, by encasing them in PVC pipes and backfilling with the surrounding sediment. This approach appeared to be capable of protecting the piles during excavation and be a potential solution for their post-excavation preservation. This preliminary study sets out to asses if this alternative approach to reburial could be an effective in situ preservation method.     

Associated conchs and opercula of Triplicatella disdoma (Hyolitha) from the early Cambrian of South Australia

Internal moulds of complete shells, including conch and associated opercula, of the hyolith Triplicatella disdoma from Cambrian Series 2, Stages 3–4 of South Australia are described. The conch of T. disdoma is shown to be narrow and cone-shaped, and with a rounded triangular cross-section. The conch shows a gentle dorsal curvature in lateral view. The fossils lack evidence of helens, and the operculum was smaller than the apertural diameter of the conch and could be withdrawn a short distance into the conch. Triplicatella was probably closely related to orthothecid hyoliths.