Arch Bridges

A. Sinopoli

• Publisher: CRC Press
• Year: 2020
• Print ISBN: 9789058090126
• eBook ISBN: 9781000150926
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Modern structural engineering surprises us with the mastery and certainty with which it plans and carries out daring projects, such as the most recent metal or concrete bridges, whether they be suspension or arch bridges. On the other hand, little is yet known about the state of knowledge of construction science and techniques which, well before the arrival of modern methods based on the mechanics of deformable continua, made it possible in the past to erect the vaulted masonry structures rthat we have inherited. The fact that these have lasted through many centuries to our time, and are still in a fairly good state of conservation, makes them competitive, as far as stability and durability are concerned, with those constructed in other materials. Although it is known that the equilibrium of the arch is guaranteed by any funicular whatsoever of the loads, contained inside the profile of an arch, finding the unique solution is not such a certainty. In other words, the problem of the equilibrium of vaulted structures is 'Poleni's problem', the one for which the Venetian scientist was able to give an exemplary solution on the occasion of the assessment of the dome of St. Peter's. Arch Bridges focuses on the main aspects of the debate about the masonry arch bridge: History of structural mechanics and construction, theoretical models, analysis for assessment, numerical methods, experimental and non-destructive testing, maintenance and repair are the topics of the Conference. The breadth and variety of the contributions presented and discussed by leading experts from many countries make this volume an authoritative source of up-to-date information.

Numerical methods for strength assessment

Finite/discrete element models for assessment and repair of masonry structures

D.R.J.Owen, D.Peric & N.Petrinic

Department of Civil Engineering, University of Wales, Swansea, UK

C.L.Brookes

Gifford and Partners, Southampton, UK

P.J. James

Cavity Lock Systems, Newport, UK

ABSTRACT: The predictive modelling of masonry structures represents a challenge due to their semi-discrete and composite nature. This paper presents an approach to modelling which considers the composite action of individual masonry components as an alternative to macro-modelling based on a homogenised continuum. A primary aim of the current research is to develop computational procedures for assessing the remnant strength of damaged masonry structures and to examine the efficiency of alternative repair strategies. Technical issues considered in the paper include the coupling of polygonal discrete elements for simulating the behaviour of masonry structures with circular discrete elements for representing geotechnical fill material. The approach adopted for parallel solution is also summarised.

1 INTRODUCTION

The ultimate objective of the work described in this paper is to develop industrially applicable computational procedures to assess alternative repair strategies for damaged masonry structures. In many instances, structures which have been damaged can be successfully repaired by the insertion of anchors, use of prestressing systems, etc.. For relatively modern structures the decision to repair, rather than demolish, may be based on economic considerations, but for historic structures the use of remedial techniques becomes a cultural necessity. Currently, appropriate stitching patterns are selected on the basis of previous experience and a major aim of the research is to provide a rational approach to determining an efficient and near-optimal anchor arrangement. In this way, an industry standard simulation capability will be provided to aid decision making in quantifying the remnant structural integrity of masonry structures and to examine optional remedial actions.

The predictive modelling of the behaviour of masonry structures, particularly in the non-linear range, remains a challenge, due predominantly to their semi-discrete and composite nature. An adequate computational model must include the fundamental mechanisms that characterise the composite action: (i) sliding along a bed or head joint at low values of normal stress, (ii) cracking of the masonry units (bricks, blocks, etc.) in direct tension, (iii) diagonal tensile cracking of masonry units at values of normal stress sufficient to develop frictional behaviour in the joints and (iv) splitting of units in tension as a result of mortar dilatency at high values of normal stress. Further aspects which may require consideration include the treatment of reinforcement and/or prestressing in composite construction techniques or repaired structures. To date, most computational predictions have been based on a macro-modelling approach, in which attempts are made to incorporate some or all of the phenomena described above within a continuum description; employing homogenisation concepts to produce a smeared representation of the brick/joint action and classical plasticity concepts to model the tensile/compressive failure of the resulting composite. Such a modelling strategy has been dictated both by the limits of available computing power and the lack of maturity of other semi-discrete computational techniques.

Whilst considerable fundamental information can be derived from solutions based on a continuum approach, a more natural treatment of this class of problem is offered by use of discrete element methods. The use of discrete elements originated in geotechnical and granular flow applications and are based on the concept that individual material elements are considered to be separate and are (possibly) connected only along their boundaries by frictional/adhesive contact. With present day computational power large scale discrete element models can be considered and for industrial applications in the field of rock blasting, etc. 10-50,000 elements are routinely employed.

Earlier work on discrete element techniques was based on the assumption that each element was rigid, but later extension to include local deformation has permitted a more rigorous treatment of both the contact conditions and fracture requirements. The incorporation of deformation kinematics into the discrete element formulation has also led naturally to a combined finite/discrete ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• History of structural mechanics
• History of construction
• Equilibrium and limit analysis
• Theoretical models and analysis
• Numerical methods for strength assessment
• Non-destructive testing
• Dynamics and experimental testing
• Special problems and new design
• Conservation and maintenance
• Repair and strengthening
• Supplement
• Author index