John P. Forth

Superstructure Behavior of a Stub-Type Integral Abutment Bridge

Records show that research leading to the successful introduction of integral-type structures such as continuous beams and frames actually began in the 1930s. Simple stub-type abutments have been found to perform well and are recommended for widespread use. The purpose of this analysis was to consider the behavior of the superstructure and substructure/backfill soil when they are subjected to thermally induced lateral movement and vertically imposed load at deck level. With the Oasys Safe finite-element analysis programs, finite-element models were developed to represent a typical stub-type integral abutment bridge configuration and backfill/foundation soil profile. It was found that the behavior of the superstructure of an integral bridge was predominantly influenced by the loading magnitude, irrespective of backfill soil properties. The results suggest that when designing the superstructure, the design requirements to resist the imposed loading may be sufficient to accommodate any effects attributable to the thermal load.

Three Resilient Megastructures by Pier Luigi Nervi

Resilience, as the ability of a structure to withstand threats and continue to function, is normally related to durability and performance to accepted standards over time. The resilience of a structure can be threatened by poor design, changes in the publics perception of style, the potential for a change in use, and structural attack; catastrophic events such as fire, explosion, or impact are usually considered the main threats for resilience. In the contemporary built environment, resilience is considered increasingly important; it has, in fact, become one of the major design issues, especially for large, iconic or public and prominent structures, which has not always been the case. Following World War II (WWII), building designers faced the necessity to conceive projects within severe financial constraints, hence the proliferation of a low quality and limited life-span structures — buildings that were designed to be replaceable, cheap, and perhaps anonymous. This approach was thought to be an effective answer to quickly accommodate the large number of people moving towards the urban environment partly destroyed by the WWII. These very buildings now constitute the backbone of our urban scenery and, although some still function adequately, many are perfect examples of structures that exhibit a lack of resilience. Fortunately, a few designers refused this post-war tendency and attempted to design lasting structures of quality, most were engineers. This is not a coincidence, engineers had less to do with the issue of providing residential accommodations and more with the erection of large structures, which necessitated a higher quality control on materials and technologies: Pier Luigi Nervi was one of them. This work considers three large structures designed and built 50 years ago, in 1961, by the Italian engineer. The structures are the bus station at the George Washington Bridge in New York (USA); the Burgo Paper Mill in Mantua (Italy); and the Palace of Labour in Turin (Italy). All of these buildings are hybrid structures (concrete and steel), an unusual choice for Nervi that perhaps reflects the design climate at the time; These buildings reacted quite differently to the events that have occurred over the past half century. One of the key factors to achieve resilience it is considered to be the quality of the buildings, which includes their ability to perform maintenance. The lack of which for whatever reason, this study aims to demonstrate, will inevitably result in a weak performance in terms of resilience on the long run.

Study of Composite Behavior of Reinforcement and Concrete in Tension

This paper aims to further the understanding of the interaction between reinforcement in tension and the surrounding cracked concrete. This is achieved using the elastic analysis of axisymmetric prisms reinforced with a single central bar. As a preliminary to the analyses, the behavior of axially reinforced prisms is described based on previous experiments. This preliminary analysis confirms that the elastic analysis adopted in this investigation is reasonable. Two analytical exercises are described: the first assumes no slip, plasticity, or internal cracking at the interface between the steel and the concrete; the second introduces internal cracking and debonding between ribs. The first analysis indicates that shear deformation of the surrounding concrete accounts for a substantial proportion of the surface crack width, and therefore that this form of deformation cannot be ignored in crack prediction formulae. The second analytical exercise shows that the internal cracking model described by Goto is appropriate.

Use of Fine Fraction

As an outcome of recycling the mineral part of construction and demolition waste significant quantities of the fine fraction, particle size below 4 mm in Europe, are generated. A common feature of the produced fine recycled aggregates is the high content of cement paste that could impair its quality. With the recent advances on the processing technologies improvement on the characteristics of the fine fraction of C&DW can be envisaged and new perspectives to their application arise.

Integral Pile-Backfill Soil Relationship in Stub-Type Integral Abutment Bridge

Temperature effects are significant to the sustainability of integral abutment bridges with the elimination of expansion joints. The thermally induced lateral movement of the structural components is opposed by the backfill soil supporting the components of integral abutment bridges. A 2D finite element analysis was performed on a typical integral abutment bridge using OASYS SAFE to investigate the complex interactions that exist between the pile supporting stub-type integral abutment and the backfill soil. The primary objective of this paper is to compare the effect of various soil types on the displacement of the piles when subjected to lateral loading and secondly to identify the significance of cyclic lateral load on the behaviour of the piles for various foundation soil types. The results suggest similar effect on the integral pile displacements for investigated soil types, especially for non-cyclic lateral loading.

Implementation of linear numerical analysis for integral abutment bridge-soil interaction

Integral bridges are bridges constructed with no expansion joints. Integral bridges are known for their superiority compared to conventional bridges which is well documented. The complicated soil-structure interaction presents a major uncertainty for integral bridges. This study describes the implementation of linear numerical analysis model which incorporates the soil response. Three models developed using Oasys GSA for the purpose of this study. The primary objectives of this study are to investigate the behaviour of structural elements of the integral abutment bridge under various load cases through finite element linear analyses and to identify a simple comprehensive model for numerical analyse of a typical integral abutment bridges. The findings of this study agree well with published work. Full meshed finite element model provides better understanding on separation between soil media and structure.