Aftab Mufti

University of Manitoba | UMN · Department of Civil Engineering

The Canadian Highway Bridge Design Code uses the concept of a target reliability index for evaluating the load-carrying capacity of existing bridges. This index, which is based on risk to human life, is related to three aspects of uncertainties inherent in a bridge: element behaviour, system behaviour and inspection level. It is assumed that all br...

The SHM is a useful tool to improve the knowledge of an existing structure. Through the analysis of recorded data of selected physical phenomena, the SHM allows to understand the behaviour of a monitored structure. Data can be obtained through measurements during static or dynamic tests set up on purpose, or acquired on environmental vibrations or...

Several provinces in Canada have modified the live load model specified in national bridge design codes to account for locally permitted trucks. Manitoba similarly introduced a live load model for the design of provincial bridges in accordance with AASHTO LRFD, the Modified HSS-25. This article presents truck weight datasets and methods used to dev...

Truck size and weight regulations have been a key instrument used to improve trucking productivity, safety, and operational performance in Canada. In response to these changes, bridge design codes undergo modifications to envelop the potential range of trucks in operation. A five-decade timeline is presented: (1) to document how bridge codes and th...

Reducing greenhouse gas emissions including carbon dioxide (CO2) is central to minimizing the human contribution to global warming. Industrial activities and transportation are some of the main contributors to carbon dioxide emission. Bridges are the key element in the transportation system and many of them are reaching the end of their designed se...

Community resilience against major disasters is a multidisciplinary research field that garners an ever-increasing interest worldwide. This paper provides summaries of the discussions held on the subject matter and the research outcomes presented during the Second Resilience Workshop in Nanjing and Shanghai. It, thus, offers a community view of pre...

Objective: Transarterial chemo-embolization (TACE) is a palliative treatment option for hepatocellular carcinoma (HCC) with improved patient survival. The aim of the study was to see the outcome of our patients at our institution 2 years post TACE. Patients and Methods: Electronic records were retrospectively reviewed for patients who had TACE from...

This chapter highlights some of the main drivers and challenges for research on risk control of critical infrastructure systems, relates to selected similar road-mapping approaches for motivating the overarching main questions posed to the working groups, and attempts to formulate some more operational sample questions for each workshop topic. Resi...

The Canadian Highway Bridge Design Code (CHBDC) uses the concept of a target reliability index for evaluating the load carrying capacity of existing bridges. This index, which is based on risk to human life, relates to three aspects of uncertainties inherent in a bridge; (a) element behaviour, (b) system behavior, and (c) inspection level, where th...

The designs for live loads of bridges are specified by the codes. The codes are based upon data collected from traffic loads, after some adjustments, using a survey on truck weights in a weighing station. In recent decades, the characteristics of trucks can be found either by pavement weigh-in-motion or bridge weigh-in-motion (BWIM) systems. There...

Composite action between steel girders and concrete slab is an important mechanical feature that needs to be maintained so that bridges can carry the applied load safely. This mechanical feature is maintained through the shear studs installed at the top flange of the steel girders. These shear studs keep the steel girders and the concrete slab work...

This paper discusses the reasons why civil engineers are very conservative in the design of new structures and the evaluation of existing structures. It is argued that structural health monitoring will assist in providing data that could be used to fine-tune the calibration of load and strength factors leading to more efficient and economical desig...

Civil infrastructures, being essential for modern and advanced societies, are the foundation of the dynamic economy and improvement of the quality of people’s lives. The design and construction of such infrastructures involve a significant cost to a country, but the proper use of the scientific methods to monitor and maintain these structures can i...

The Canadian Highway Bridge Design Code uses the concept of a target reliability index for evaluating the load carrying capacity of existing bridges. This index, which is based on risk to human life, is related to three aspects of uncertainties inherent in a bridge: those related to (a) element behaviour, (b) system behavior, and (c) inspection lev...

Composite action between steel girders and concrete deck slabs is an important feature of slab-on-girder bridges. The composite action between steel girders and concrete slabs is maintained through the shear studs installed at the top surface of the top flange of the steel girders. These shear studs keep the steel girders and the concrete deck slab...

Bridges are key elements of the transportation system. The load carrying capacity of a bridge can be evaluated through load testing. However, this only provides a snap shot of the structure at a particular time. In this work, sensors, including strain gauges, accelerometers, and thermocouples, are used to collect real time structural responses to t...

It is critical to detect cracks in steel girders of bridges before they have the potential to compromise the integrity of the structure. Both distributed binary sensors and distributed fiber optic sensors are capable of detecting cracks that are wider than 0.2 mm in steel girders. The objective of this paper is to report the optimum placement of th...

Three highway bridges in the Canadian province of Manitoba are being monitored continuously not only for their long-term performance but also for bridge weighing-in-motion (BWIM). Data collected for the BWIM study has led to some observations that have far-reaching consequences about the design and evaluation loads for highway bridges. This paper p...

Small bowel is not easily accessed by endoscope and diagnosis of its pathology relies on clinical assessment and imaging. Traditional contrast studies have the disadvantage of not including the mural and extramural details. This is best seen with magnetic resonance enterography (MRE) which is rapidly replacing computed tomography enterography due t...

Steel girder bridges make up a significant percentage of all bridges. Many of the steel girder bridges are aging and approaching their designed service lives. Crack formation and its propagation over time is one of the main deficiencies of aging steel girders and may result in unusable or unsafe service conditions. The existing distributed crack de...

Three highway bridges in the Canadian province of Manitoba are being monitored continuously not only for their long-term performance but also for bridge-weighing-in-motion (BWIM). Data collected for the BWIM study has led to some observations which have to far-reaching consequences about the design and evaluation loads for highway bridges. This pap...

In both the Canadian and American design codes for highway bridges, the design live load is based on the assumption that the number of truck loads are equally divided in all lanes of a bridge. The same assumption is true for the live loads specified for the evaluation of the load carrying capacities of existing bridges. Recent long-term monitoring...

Axle detection is a critical monitoring process that needs to be implemented on bridges so that the number of axles of crossing vehicles can be determined. Most bridge design codes specify bridge design loads based on certain trucks configurations. Reviewing and updating bridge design codes depend on an accurate measurement of the nature of the loa...

Steel girder bridges make up a significant percentage of all bridges. Many of the steel girder bridges are aging and approaching their designed service lives. Crack formation and its propagation over time is one of the main deficiencies of aging steel girders and may result in unusable or unsafe service conditions. The existing distributed crack de...

It is well documented that civil infrastructure, including steel bridges, are aging and are approaching the end of their design service life. One of the challenging problems with aging steel girder bridges is the potential for crack formation and propagation that may result in unusable service conditions. Timely detection of cracks demands frequent...

Manitoba has many ageing steel bridge structures on its highway network that are facing increased axle loads, speed, and traffic intensity, all of which accelerate their deterioration due to fatigue. An immediate replacement or rehabilitation is not feasible for the existing structures that have already approached their expected service life. The r...

North American infrastructure, including steel bridges, are aging and reaching the end of their service lives. Over time, environmental stresses and cyclic truck traffic over bridges may lead to crack formation and crack propagation in the steel girders used in bridges. Cracks in steel girders decreases the load bearing capacity of the superstructu...

Bridges in regions where temperature range between seasons is large are affected significantly by the temperature range. The temperature affects bridges in different forms, one of which is the reactions that they develop in the bottom flanges of girders against the horizontal movement. Bearing restraint due to temperature change was studied in two...

Structural health monitoring systems are required to detect the presence of cracks on structures. Currently available sensing systems are costly and difficult to install. In this work, a new crack sensing system based on the propagation of cracks from the structure through a bonded conductor is presented. The conductor is severed when a crack on th...

Bridge weigh in motion (B-WIM) uses accurate sensing systems to transform an existing bridge into a mechanism to determine actual traffic loading. This information on traffic loading can enable efficient and economical management of transport networks and is becoming a valuable tool for bridge safety assessment. B-WIM can provide site-specific traf...

A soil-steel bridge is a structure made with a shell of manufactured curved corrugated steel plates and an envelope of engineered soil, which is well-compacted backfill composed mainly of well-graded granular soil. A photograph of a soil-steel bridge serving as a grade-separation structure is presented in Fig. 7.1. These structures are, however, al...

The acceptance that fibre reinforced polymers (FRPs) have so far gained for new structures is not in proportion to their potential, because their short-term costs are usually higher than those for structures with conventional materials. Designers and owners have usually justified the use of FRPs in new structures on the basis of life-cycle costing....

Structural health monitoring (SHM) is the integration of a sensory system, a data acquisition system, a data processing and archiving system, a communication system, a damage detection system and a modeling system to acquire knowledge about the integrity and load-worthiness of in-service structures on either a temporary or continuous basis.

In a realistic bridge design code, the design live loads should be based on actual traffic loads, as discussed in Chap. 1. In the past, the information about the actual traffic loads on highway bridges was obtained from truck surveys, in which the trucks are stopped for measurement and weighing on ‘static’ weighing scales. During the past few decad...

As discussed in the introduction to Chap. 2, the term is being used in this book for the determination of load effects in the various components of a bridge superstructure subjected to vehicle loads. The methods employed for bridge analysis range in complexity from the overly simplified D-type method of AASHTO (1989) to highly complex finite elemen...

The concrete deck slabs of girder bridges are usually projected transversely beyond the outermost girders. These projections, which are provided for reasons of economy and aesthetics, are referred to in this book as cantilever slabs or cantilever overhangs.

Madsen, a leading expert in his times in the structural use of wood made a clear distinction between the terms wood and timber. He used the former term for defect-free samples, which are employed for determining the fundamental properties of this building material, and reserved timber for that useful construction material, which is produced from lo...

In 1989, the authors of this book and their friend L.G. Jaeger (1926–2013) wrote a brief article inquiring if the time had come in Canada for the use of the advanced composite materials, now known as fibre reinforced polymers (FRPs), in civil structures (Mufti et al. 1989). The premise for the apparently affirmative answer to their query lay in the...

The term deck slab is typically used in North America to describe the concrete slab of a girder bridge which supports the vehicle loads directly before transmitting their effects to the girders. In this chapter and elsewhere in this book, the term is used with this same meaning, rather than to describe a slab bridge as is done in some countries.

In structural engineering, the term usually refers to in which the distribution of force effects is determined in the various components of a structure. The responses of a structure such as deflections and bending moments are often referred to as load effects. Another infrequently used term in structural engineering is which refers to the process o...

Although not generally appreciated by lay people, it is not possible to design and construct a structure that will remain safe against failure under all conditions and at all times.

In a bridge design code, the design live loads should be based on actual traffic loads. In the past, the information about the actual truck loads on highway bridges was obtained from truck surveys, in which the trucks are stopped for measurement and weighed on ‘static’ weighing scales. During the past few decades, however, the information about tru...

Engineers have proposed the idea that there may be some arching action present in bridge deck cantilever overhangs stiffened along their longitudinal free edge through a traffic barrier, subjected to a wheel load. This paper includes the details of a full-scale corrosion-free bridge deck with cantilever overhangs stiffened along their longitudinal...

Preservation and rehabilitation of valuable historic heritage buildings require effective and efficient monitoring systems to ensure proper maintenance of durability and functionality of the building structures and materials. Moisture transport and retention in building infrastructure are some of the most common problems, often inducing structural...

This article presents the results from an experimental program designed to evaluate the performance of a system consisting of a readout unit and a ribbon type Fiber Optic Sensor (FOS) based on Brillouin Optical Time Domain Analysis (BOTDA). The system is intended for the detection of cracks as well as the monitoring of long-term performance for ste...

Assessing the safety of heritage structures such as the Parliament Buildings of Canada became a priority with the publication of the 2005 National Building Code of Canada. The exterior walls of the West Block on Parliament Hill consist of multi-wythe unreinforced stone masonry. The exterior face of these walls is constructed from sandstone, while t...

This paper presents a synthesis of the design provisions of the second edition of the Canadian Highway Bridge Design Code (CHBDC) for fibre-reinforced structures. New design provisions for applications not covered by the first edition of the CHBDC and the rationale for those that remain unchanged from the first edition are given. Among the new desi...

This paper presents an overview of the development and application of ISIS fibre optic sensor (FOS) technology by the University of Toronto Institute for Aerospace Studies and Department of Electrical and Computer Engineering. The primary focus of this technology has involved the use of fibre Bragg gratings (FBGs) to measure strain and temperature...

Tall buildings, or skyscrapers, are icons of cities, symbols of corporate power, and a mark of national pride. Certain skyscrapers, such as the John Hancock Center and the Sears Tower in Chicago, are also marvels of engineering that have paved the way for ever increasing heights of structural systems. Since the 1960s, a series of new structural sys...

The problem of punching shear usually arises in reinforced concrete slabs subjected to concentrated loads and particularly in concrete bridge decks due to development of an internal arching system. Ongoing research revealed that the governing mode of failure of concrete bridge decks is not flexure and that using a flexural design method usually led...

Development of an efficient and durable bridge deck system is a priority for most highway departments worldwide. This paper summarizes the results of an experimental program designed to study the behaviour of innovative glass-fiber-reinforced-polymer (GFRP) bridge deck modules and their transverse connection. The deck consisted of a number of trian...

As the design and construction of civil structures continue to evolve, it is becoming imperative that these structures be monitored for their health. To meet this need, the discipline of civionics has emerged. It involves the application of electronics to civil structures and aims to assist engineers in realizing the full benefits of structural hea...

It is now well established that concrete deck slabs of slab-on-girder bridges subjected to concentrated loads develop an internal arching system provided that certain conditions of confinement of the concrete are met. Because of this arching system, the deck slab, being predominantly in compression, fails in punching shear rather than in flexure. T...

Experimental tests on half-scale models have demonstrated that polypropylene-fibre-reinforced concrete (PFRC) bridge deck slabs completely devoid of conventional steel reinforcement will fail by punching shear under concentrated loads considerably greater than those specified for design, provided the top flanges of the supporting girders are adequa...

In many phases of structural design and analytical evaluation, the solution of stress and strain distribution in an elastic continuum is required. Special cases of such problems may range from two-dimensional plane stress or plain strain distribution, plate bending to analysis of fully three-dimensional solids. The finite element programs are often...

Due to the severe environment in which it stands, this unique structure has been extensively instrumented in order to monitor its condition over its service life of 100 years. Fibre-optic strain gages were installed by ISIS Canada as part of a project to assess the feasibility of using this type of sensor for monitoring civil engineering structures...

Recent advancements in the fields of fiber reinforced polymers (FRPs) have resulted in the development of new materials with great potential for applications in civil engineering structures, and due to extensive research over recent years, FRPs are now being considered for the design of new structures. This study describes how carbon fiber reinforc...

This note discusses the use of the steel-free concrete bridge deck technology in continuous span bridge structures. Conventional slab-on-girder design often utilizes the longitudinal steel reinforcement in the deck to resist the negative bending moments created at the internal piers of continuous bridges. The steel-free bridge deck is devoid of all...

To study systematically the role of each layer of steel reinforcement in conventionally reinforced deck slabs of girder bridges, a full-scale model was built of a 175 mm thick concrete deck slab on two steel girders with a center-to-center spacing of 2.0 m. The 12 m long deck slab was conceptually divided into four 3 m long segments, identified as...

This paper presents what is believed to be the first successful attempt to apply an elastoplastic material model to planar reinforced concrete under cyclic loads. The model treats an element of reinforced concrete in biaxial stress states, and provides for the cracking and crushing of concrete, opening and closing of previously formed cracks, and y...

Load distribution characteristics of cellular structures are greatly influenced by transverse cell distortion and because of this these structures require a somewhat different analysis than those used for other common types of bridges.This paper summarizes the results of an extensive literature search and initial review of the current methods of an...

The purpose of this paper is to analyze the fatigue crack growth rate in groove weld with backing steel bar. The linear elastic fracture mechanics approach is used. This approach is coded in a special purpose fracture mechanics package FAST. By using FAST, the structure is modeled and analyzed by its finite element module FAST-I, and the cyclic lif...

The presence of moisture in the masonry structures has a great impact on the strength and integrity of building. Moisture controlling paradigms for preventing structural deterioration and performance degradation from the water content require effective moisture monitoring systems. However, most moisture sensors require the use of wires. This paper...

This paper presents an overview of structural-health-monitoring technologies for constructed structures, based on six field demonstration projects in Canada. The principle of fibre-optic sensors is discussed, including the fibre Bragg grating, Fabry-Perot and long-gauge sensors together with their positive and negative aspects. Site applications of...