Structural health monitoring of highway bridges in Zambia by using sensor technology: a case study of Nansenga bridge

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Kasumba, Hopeson
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The University of Zambia
Structural Health Monitoring by use of Visual inspections of bridge structures can be subjective and inaccurate. Recent developments in sensing, communication and information technologies, however, have completely modernized the inspection procedures and significantly increased the efficiency in terms of labor and time. In recent years, innovations have led to the development of high-tech-based systems that range from sensing the structural condition or loading, to knowledge- based decision making. With such advanced technologies, a large number or portions of infrastructure can be managed in a fast and cost effective manner. Bridge infrastructure are integral elements to transportation infrastructure, therefore Structural Health Monitoring (SHM) is essential to assess the integrity of load carrying capacity, safety and economic maintenance interventions. Damage to bridge structures can arise from a number of situation such as; prolonged use with increased imposed loads, environmental effects, inadequate maintenance and construction errors. This research focused on multiscale structural health monitoring of bridges in Zambia using wireless sensor technologies, with case studies on the Nansenga Bridge located on the Turnpike-Livingstone Road (T1). A rational decision making tool for conducting effective and efficient SHM of highway bridges has been proposed through this research Nondestructive testing and evaluation techniques were used to collect data on the current condition of the Bridge. Due to lack of Design data and as built drawings on older bridges, a redesign of Nansenga Bridge was conducted to BS5400 parts 2&4 of 1978 in order to verify the incorporated rebar sizes, placement and spacing. With verified collected data, a Finite Element (FE) model of Nansenga was developed using FEM design 17 software, whereby moving load was applied to study both linear and dynamic responses of the bridge. Highly distressed regions from FE simulations agreed with onsite localized damage detected on the bridge deck and girders. Crack widths of 1.00mm to 1.75mm, which exceed maximum allowable width of 0.30mm, were detected thereby exposing both concrete and reinforcement to abnormal stress conditions. This excessive damage requires immediate attention by the agency responsible for roads as this bridge is on a Trunk Road, T1, linking Zambia to other SADCC countries (South Africa, Botswana and Namibia). Ultrasonic pulse velocity tests indicated crack depths of 50mm to 300mm on the Nansenga Bridge beams. Key words:Structural Health Monitoring, Sensors, Non Destructive Testing,Finite element modelling
Structural health management--Zambia , Transportation infrastructure--Zambia , Bridge infrastructure