Use of Just in Time Maintenance of Reinforced Concrete Bridge Structures based on Real Historical Data Deterioration Models

Concrete is the backbone of any developed economy. Concrete can suffer from a large number of deleterious effects including physical, chemical and biological causes. Large owning bridge structures organizations are facing very serious questions when asking for maintenance budgets. The questions range from needing to justify the need for the work, its urgency, to also have to predict or show the consequences of delayed rehabilitation of a particular structure. There is therefore a need for a probabilistic model that can estimate the range of service lives of bridge populations and also the likelihood of level of deteriorations it can reached for every incremental time interval. A model was developed for such estimation based on statistical data from actual inspection records of a large reinforced concrete bridge portfolio. The method used both deterministic and stochastic methods to predict the service life of a bridge, using these service lives in combination with the just in time (JIT) principle of management would enable maintenance managers to justify the need for action and the budgets needed, to intervene at the optimum time in the life of the structure and that of the deterioration. The paper will report on the model which is based on a large database of deterioration records of concrete bridges covering a period of over 60 years and include data from over 400 bridge structures. The paper will also illustrate how the service life model was developed and how these service lives combined with the JIT can be used to effectively allocate resources and use them to keep a major infrastructure asset moving with little disruption to the transport system and its users

Lecture Notes in Civil Engineering

The goal of this study is to deal with the modelling and calculation of the ground-borne vibrations and the effect of the wave propagation on foundation response with emphasis on vibration screening systems. Herein, ANSYS FEM software program was used to simulate vibratory source induced wave propagation and dynamic foundation-soil interaction problem. Extensive parametric investigations on the screening performance of open and in-filled trench barriers have been done for both active and passive isolation cases. The obtained results are important for structural engineers since provide practical information and methods about the dissipation of the strong vibration energy

Lecture Notes in Civil Engineering

This research primarily aims to investigate experimentally the mechanical behavior and the crack pattern of the perforated brick block masonry specimens under shear stresses before and after reinforcing procedure with seismic textile. The reinforcing system is a combination between an inorganic matrix made with natural hydraulic lime and white cement and a hybrid multiaxial seismic textile made from Alkali Resistant (AR) glass and polypropylene fibers. The effect of the single-sided application of the sand plaster on the non-strengthened wall specimens is also tested to compare with both reference and retrofitted specimens. The obtained results of the triplet shear tests are given in the manner of force-displacement curves comparatively for all specimens considered without/with textile reinforcement. The shear strength for each triplet specimen investigated is also obtained. The effect of the presence of seismic textile as well as the applied sand plaster on the mechanical behavior of the triplet specimens is emphasized. It is concluded that the shear resistance and the ductility highly influenced by using the seismic textile and relevant plaster

O.R. modelling of the deterioration and maintenance of concrete structures

This paper reports on a collaborative venture between operational researchers and civil engineers over 3 years. The main objectives were to collect and publish data on the observed rates of deterioration of particular defect types in a large number of concrete bridges, and to develop predictive mathematical models that relate inspection frequency to maintenance costs. The motivation was in part associated with the prototype modelling paper for inspection practices of major concrete structures, Christer (1988). The paper reports on the analysis of data collected and the estimation of deterioration using the concept of delay time. The two phase delay time model is extended to an extra phase in order to model the process of cracking and spalling in concrete. Maximum likelihood techniques are used to estimate modelling parameters and an appropriate test of fit is carried out. Cost based models are then formulated to predict the cost effects of maintenance and inspection decision options. The cost model is applied first to an element, and then to an aggregate number of component types to produce a cost model for maintenance of a bridge or set of bridges

Comparison of in situ sequence type analysis of Legionella pneumophila in respiratory tract secretions and environmental samples of a hospital in East Jerusalem.

Legionella pneumophila genotyping is important for epidemiological investigation of nosocomial and community-acquired outbreaks of legionellosis. The prevalence of legionellosis in pneumonia patients in the West Bank was monitored for the first time, and the sequence types (STs) from respiratory samples were compared with STs of environmental samples from different wards of the hospital. Sputum (n = 121) and bronchoalveolar lavage (BAL) (n = 74) specimens were cultured for L. pneumophila; genomic DNA was tested by 16S rRNA polymerase chain reaction (PCR) amplification. Nested PCR sequence-based typing (NPSBT) was implemented on DNA of the respiratory and environmental PCR-positive samples. Only one respiratory specimen was positive for L. pneumophila by culture. BAL gave a higher percentage of L. pneumophila-positive samples, 35% (26/74) than sputum, 15% (18/121) by PCR. NPSBT revealed the following STs: ST 1 (29%, 7/24), ST 461 (21%, 5/24), ST 1037 (4%, 1/24) from respiratory samples, STs from environmental samples: ST 1 (28.5%, 4/14), ST 187 (21.4%, 3/14) and ST 2070, ST 461, ST 1482 (7.1%, 1/14) each. This study emphasises the advantage of PCR over culture for the detection of L. pneumophila in countries where antibiotics are indiscriminately used prior to hospital admission. ST 1 was the predominant ST in both respiratory and environmental samples