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A new modelling technique is developed to model the nonlinear behaviour of corrosion damaged reinforced concrete (RC) bridge piers subject to cyclic loading. The model employs a nonlinear beam-column element with multi-mechanical fibre sections using OpenSees. The nonlinear uniaxial material models used in the fibre sections account for the effect of corrosion damage on vertical reinforcing, cracked cover concrete due to corrosion of vertical bars and damaged confined concrete due to corrosion of horizontal tie reinforcement. An advance material model is used to simulate the nonlinear behaviour of the vertical reinforcing bars that accounts for combined impact of inelastic buckling and low-cycle fatigue degradation. The basic uncorroded model is verified by comparison of the computation and observed response of RC columns with uncorroded reinforcement. This model is used in an exploration study of recently tested reinforced concrete components to investigate the impact of different corrosion models on the inelastic response of corrosion damaged RC columns.

A series of pushover and cyclic analyses on a hypothetical corroded RC columns are conducted. The impact of corrosion on reinforcing steel and concrete is modelled. The influence of cyclic degradation due to low-cycle fatigue is also modelled.

(1) Corrosion has a more significant impact on ductility loss of RC columns than the strength loss (plastic moment capacity). (2) It was found that the flexural failure is initiated by buckling of vertical bars and crushing of core concrete which then followed by fracture of bars in tension. (3) The analyses results showed that for seismic performance and evaluation of existing corroded bridges monotonic pushover analysis is insufficient. The cyclic degradation due to low-cycle fatigue has a significant influence on the response of corroded RC columns.

The finite element developed in this paper is the most comprehensive model to date that is able to capture the onlinear behaviour of corroded RC columns under cyclic loading up to complete collapse.

About 26,000 Airey Houses were erected during the post war years (1946–55) as part of the house building programme of that period. The Airey House is essentially a prefabricated concrete structure which was erected on site to form a box. This box was erected upon a concrete raft which acted as the foundation and floor of the dwelling. The basic box was formed from several framed ‘goal posts’ to which thin concrete cladding panels were fastened to the upright columns by copper wire. The vertical loading from the first floor and roof is taken on the vertical columns but may also be shared with the concrete cladding panels (see Figure 1).

Seismic assessment procedures of RC members quantify member strength, deformation capacity and failure mode using detailed information regarding member geometry and reinforcement amount and arrangement. However, the condition of the reinforcing materials is not explicitly accounted for in the calculation process. The paper aims to discuss this issue.

This problem is explored in the present paper through consistent evaluation of the evidence from a database of column tests which were subjected to cyclic lateral load reversals simulating earthquake effects after being subjected to accelerated corrosion. The column performance expressed in terms of the shear vs drift resistance envelope is introduced in the available methodologies of rapid assessment of reinforced concrete structures showcasing the limitations and uncertainties of the existing state of the art in the field of seismic assessment of existing structures.

Simple estimations as well as experimental observation show that the effect can be staggering, in terms of reduced deformation capacity, prevailing mode of failure and residual strength under seismic loading. It has been observed in the field that deterioration and ageing can reduce a well detailed structural component to behave as a poorly constructed one, by means of cover delamination, transverse and longitudinal bar area loss and steel embrittlement.

The amount of deterioration in the residual life of the component, in the face of a future seismic hazard, is fraught with uncertainty regarding the amount and intensity of material deprecation and the manner in which this may be considered in the logistics of the assessment process.

To understand the seismic behavior of reinforced concrete (RC) beams confined by corroded stirrups, low-reversed cyclic loading tests were carried out on seven RC beam specimens with different stirrup corrosion levels and stirrup ratios to investigate their mechanical characteristics.

The failure mode, hysteresis behavior, skeleton curves, ductility, stiffness degradation and energy dissipation behavior of RC specimens are compared and discussed. The experimental results showed that the restraint of concrete provided by corroded stirrups is reduced, which leads to a decline in seismic performance.

For the specimens with the same ratios of stirrup, as the corrosion level increased, the load-carrying capacity, stiffness, plastic deformation capacity and energy-dissipation capacity dropped significantly. Compared with the uncorroded specimen, the failure modes of specimens with high corrosion level changed from ductile bending failure to brittle failure. For the specimens with the same levels of corrosion, the higher the stirrup ratio was, the stronger the restraint effect of the stirrups on the concrete, and the seismic behavior of the specimens was obviously improved.

In this paper, a total of seven full-size RC beam specimens at joints with different stirrup corrosion levels and stirrup ratios were designed and constructed to explore the influences of corrosion levels and stirrup ratios of stirrups on the seismic performances. The failure modes, strain of reinforcement, hysteretic curves, skeleton curves, stiffness degradation and ductility factor of RC specimens are compared and discussed.

As it is widely known, corrosion is a major deterioration factor for structures which are located on coastal areas. Corrosion has a great impact on both the durability and seismic performance of reinforced concrete structures. In the present study, two identical reinforced concrete columns were constructed and mechanical tests were organized to simulate seismic conditions. Prior to the initiation of the mechanical tests, the base of one of the two columns was exposed to predetermined accelerated electrochemical corrosion (at a height of 60 cm from the base). After the completion of the experimental loading procedure, the hysteresis curves – for unilateral and bilateral loadings – of the two samples were presented and analyzed (in terms of strength, displacement and dissipated energy). The paper aims to discuss this issue.

In the present study, two identical reinforced concrete columns were constructed and mechanical tests were organized to simulate seismic conditions. The tests were executed under the combination of a constant vertical force with horizontal, gradually increasing, cyclic loads. The implemented displacements, of the free end of the column, ranged from 0.2 to 5 percent. Prior to the initiation of the mechanical tests, the base of one of the two columns was exposed to predetermined accelerated electrochemical corrosion (at a height of 60 cm from the base). After the completion of the experimental loading procedure, the hysteresis curves of the two samples were presented and analyzed (in terms of strength, displacement and dissipated energy).

Analyzing the results, for both unilateral and bilateral loadings, a significant reduction of the seismic performance of the corroded column was highlighted. The corrosion damage imposed on the reference column resulted in the dramatic decrease of its energy reserves, even though an increase in ductility was recorded. Furthermore, more attention was paid to the consequences of the uneven corrosion damage, recorded on the steel bars examined, on ductility, hysteretic behavior and damping ratio.

In the present paper, the influence of the corrosion effects on the cyclic response of structural elements was presented and analyzed. The simulation of the seismic conditions was achieved by imposing, at the same time, a constant vertical force and horizontal, gradually increasing, cyclic loads. Finally, an evaluation of the performance of a column, under both unilateral and bilateral loadings, took place before and after corrosion.

Several experimental and numerical studies were performed in the past to estimate buckling capacity of corroded tubular members. However, the effect of initial imperfections has not been properly considered in most of these earlier proposed formulas. Therefore, the main objective of this paper is to propose an accurate analytical formula to determine the buckling capacity of patched corroded tubular members.

Tubular members with initial geometrical imperfections can be regarded as beam-columns because of the combination of axial load and bending moment. The proposed formula is derived for a rectangular corrosion patch. The proposed formula is verified with results from finite element analysis of corroded tubular members and experimental results. The formula is also applied to an existing offshore jacket structure to highlight its significance and applicability. It is found that the buckling capacity of jacket members in splash zone reduces significantly with ageing. This reduction is around 29 and 14% for the selected brace and leg member respectively, during the design life. Finally, it is concluded that corrosion reduces the buckling capacity significantly and the proposed formula can be easily applied by practicing engineers to give an accurate and slightly conservative estimate the remaining buckling capacity.

The main finding is the new formula which accurately and conservatively estimate the buckling capacity of corroded tubular members. The proposed formula considers the secondary effect of both initial geometrical imperfections and shifting of centroid because of corrosion.

The proposed new formula is unique and original in that it considers both secondary effects from geometrical imperfections, reduction of cross-section from corrosion wastage and shifting of centroid because of corrosion. Finally, it is concluded that corrosion reduces the buckling capacity significantly and the proposed formula can be easily applied by practicing engineers to conservatively estimate the remaining buckling capacity and verify if further, more advanced estimations are needed.

This study aims to make an effort to develop a model to predict the residual flexural strength of reinforced concrete beams subjected to reinforcement corrosion.

For generating the required data to develop the model, a set of experimental variables was considered that included corrosion current density, corrosion duration, rebar diameter and thickness of concrete cover. A total of 28 sets of reinforced concrete beams of size 150 × 150 × 1,100 mm were cast, of which 4 sets of un-corroded beams were tested in four-point bend test as control beams and the remaining 24 sets of beams were subjected to accelerated rebar corrosion inducing different levels of corrosion current densities for different durations. Corroded beams were also tested in flexure, and test results of un-corroded and corroded beams were utilized to obtain an empirical model for estimating the residual flexural strength of beams for given corrosion current density, corrosion duration and diameter of the rebars.

Comparison of the residual flexural strengths measured experimentally for a set of corroded beams, reported in literature, with that predicted using the model proposed in this study indicates that the proposed model has a reasonably good accuracy.

The empirical model obtained under this work can be used as a simple tool to predict residual flexural strength of corroded beams using the input data that include rebar corrosion rate, corrosion duration after initiation and diameter of rebars.

To summarise research undertaken by the BRE into the identification and condition assessment, of non‐traditional housing. During the 1980s, defects were discovered in the design and construction of a number of house types designed and built before 1960 and these were subsequently designated as inherently defective under the Housing Defects legislation.

The research involved several years of investigation during which many different types of pre‐cast concrete, in situ‐concrete, steel‐ and timber‐framed housing systems were investigated. This research has culminated in the publication of a major new book and CDROM.

Overall the majority of non‐traditional dwellings have provided levels of performance not very different from many traditionally built dwellings of the same age. However, there are inherent defects with several systems. Some dwellings may be beyond economic repair.

The surveyor needs to be aware of the system of non‐traditional dwelling under inspection and to understand the likely defects and necessary remedial work.

This research will inform surveyors and home inspectors of the identification of non‐traditional dwellings, modes of failure of various systems, whether economic repair is possible and what remedial action should be proposed.

This paper covers the development of a novel defect model for concrete highway bridges. The proposed defect model is intended to facilitate the identification of bridge’s condition information (i.e. defects), improve the efficiency and accuracy of bridge inspections by supporting practitioners and even machines with digitalised expert knowledge, and ultimately automate the process.

The research design consists of three major phases so as to (1) categorise common defect with regard to physical entities (i.e. bridge element), (2) establish internal relationships among those defects and (3) relate defects to their properties and potential causes. A mixed-method research approach, which includes a comprehensive literature review, focus groups and case studies, was employed to develop and validate the proposed defect model.

The data collected through the literature and focus groups were analysed and knowledge were extracted to form the novel defect model. The defect model was then validated and further calibrated through case study. Inspection reports of nearly 300 bridges in China were collected and analysed. The study uncovered the relationships between defects and a variety of inspection-related elements and represented in the form of an accessible, digitalised and user-friendly knowledge model.

The contribution of this paper is the development of a defect model that can assist inexperienced practitioners and even machines in the near future to conduct inspection tasks. For one, the proposed defect model can standardise the data collection process of bridge inspection, including the identification of defects and documentation of their vital properties, paving the path for the automation in subsequent stages (e.g. condition evaluation). For another, by retrieving rich experience and expert knowledge which have long been reserved and inherited in the industrial sector, the inspection efficiency and accuracy can be considerably improved.

This paper aims to investigate the experimental behavior and the reliability of concrete columns repaired using fiber-reinforced polymers (FRPs) under axial compression loading. The expression of the ultimate axial resistance was assessed from the experimental data of damaged concrete cylinders repaired by externally bonded double-FRP spiral strips.

The tested columns bearing capacity mainly depends of the elasticity modulus of both damaged and undamaged concrete have been considered in addition to the applied load and the cylinder diameter as random variables in the expression of the failure criterion. The reliability indicators were assessed using first order second moment method.

The emphasized test results, statistically fitted show that the strength has been retrofitted for all repaired specimens whatever the degree of initial damage. However, the gain in axial strength is inversely proportional to the degree of damage.

The efficiency of a new FRP repair procedure using double-spiral strips was studied. This research provides a technical and economical solution for retrofitting existing concrete columns. Finally, the random character of the variables that govern the studied system shows the accuracy and safety of the proposed original design.