Simulation and Behavior of Corrosion Deteriorated Reinforced Concrete Members

Several reinforced concrete (RC) infrastructures are now crumbling from corrosion of steel bars in concrete. The paper presents the recent advancements in analytical simulation of corrosion aftereffects on behavior of RC members. The model juxtaposes the experimental findings with analytical relationships. The implementation of the model into a nonlinear finite element formulation as well as the experimental and analytical backgrounds are discussed. The abilities of the resulted program have been studied by modeling some experimental specimens showing a reasonable agreement between the analytical and experimental findings

A new approach for nonlinear finite element analysis of reinforced concrete structures with corroded reinforcements

A new approach for nonlinear finite element analysis of corroded reinforcements in reinforced concrete (RC) structures is elaborated in the article. An algorithmic procedure for producing the tension-stiffening curve of RC elements taking into consideration most of effective parameters, e.g.: the rate of steel bar corrosion, bond-slip behavior, concrete cover and amount of reinforcement, is illustrated. This has been established on both experimental and analytical bases. This algorithm is implemented into a nonlinear finite element analysis program. The abilities of the resulted program have been studied by modeling some experimental specimens showing a reasonable agreement between the analytical and experimental findings

Hypoelastic modeling of reinforced concrete walls

This paper presents a new hypoelasticity model which was implemented in a nonlinear finite element formulation to analyze reinforced concrete (RC) structures. The model includes a new hypoelasticity constitutive relationship utilizing the rotation of material axis through successive iterations. The model can account for high nonlinearity of the stress-strain behavior of the concrete in the pre-peak regime, the softening behavior of the concrete in the post-peak regime and the irrecoverable volume dilatation at high levels of compressive load. This research introduces the modified version of the common application orthotropic stress-strain relation developed by Darwin and Pecknold. It is endeavored not to violate the principal of “simplicity” by improvement of the “capability”. The results of analyses of experimental reinforced concrete walls are presented to confirm the abilities of the proposed relationships

Investigation of Corrosion Effects on Bond-slip and Tensile Strength of Reinforced Concrete Members

The corrosion effect on tensile strength of RC members is very important to region with high corrosion conditions. In this article a study on finding bond behaviour, crack pattern, crack spacing, and tensile strength of RC members is presented. For this purpose a comprehensive experimental program including reinforced concrete cylanders with different concrete covers and reinforcement ratios under various corrosion rates is conducted. The specimens are located in large tub containing water and salt (5% salt solution) with a devich for accelerated corrosion production. For each specimen, the variation of total tensile strength versus its average strain is plotted and the member behaviour at various load levels is investigated. Average crack spacing, and maximum bond stress developed at each corrosion level are studied and their apporoperiate relationship are proposed. The main parameterrs considerd in this investigation are: corrosion rate (Cw), reinforcement diameter (d), reinforcement ratio (ρ), c/d and d/ρ

Corrosion effects on tension stiffening behavior of reinforced concrete

The investigation of corrosion effects on the tensile behavior of reinforced concrete (RC) members is very important in region prone to high corrosion conditions. In this article, an experimental study concerning corrosion effects on tensile behavior of RC members is presented. For this purpose, a comprehensive experimental program including 58 cylindrical reinforced concrete specimens under various levels of corrosion is conducted. Some of the specimens (44) are located in large tub containing water and salt (5% salt solution); an electrical supplier has been utilized for the accelerated corrosion program. Afterwards, the tensile behavior of the specimens was studied by means of the direct tension tests. For each specimen, the tension stiffening curve is plotted, and heir behavior at various load levels is investigated. Average crack spacing, loss of cross-section area due to corrosion, the concrete contribution to the tensile response for different strain levels, and maximum bond stress developed at each corrosion level are studied, and their appropriate relationships are proposed. The main parameters considered in this investigation are: degree concrete cover (c), ratio of of clear corrosion concrete (Cw), cover reinforcement to diameter (d), reinforcement ratio (ρ), rebar diameter (c/d), and ratio of rebar diameter clear to reinforcement percentage (d/ρ)

Ground Motion Duration Effects on the Seismic Risk Assessment of Wood Light-Frame Buildings

Wood construction comprises a large portion of building stocks of several countries across the globe with high preparedness for earthquakes including Japan, Canada, and the United States. Built environments of these countries are prone to long-duration ground shakings due largely to the proximity of subduction faulting systems. However, the current seismic design requirements do not adequately emphasize this key feature of ground motions. This study evaluates the impact of long-duration ground motions on seismic risk characteristics of code-conforming wood lightframe buildings. To this end, a study matrix of wood light-frame buildings is developed incorporating with two different heights (i.e., 1-story and 4-story) and two distinct occupancies (i.e., multi-family and commercial) designed for a very high seismic region according to the latest pertinent design requirements of the United States. The seismic performance of these buildings is assessed through incremental dynamic analysis (IDA) in accordance with FEMA P-695 recommendations. Each building is analyzed using three sets of ground motions, i.e., far-field FEMA P-695 ground motions ensemble, an ensemble of short-duration ground motions, and an ensemble of long-duration ground motions. For each building, structural responses are obtained, and collapse fragility for these three sets of ground motions are derived. Next, the structural analysis results are relayed to a component-based loss assessment framework developed based on performance-based earthquake engineering principles in order to predict the seismic risk characteristics of the adopted buildings including the vulnerability function, risk curve, and average annual loss (AAL). The loss assessment is conducted separately for the structural and nonstructural components as well as the content of the buildings. The study reveals the considerable effect of ground motion duration on the seismic vulnerability of light-frame wood buildings, specifically in the case of 4-story wood light-frame building which reveals approximately a mean increase of 140.0% in the predicted losses

A Probabilistic Casualty Model to Include Injury Severity Levels in Seismic Risk Assessment

Despite the increasing adoption of Performance-Based Earthquake Engineering (PBEE) in seismic risk assessment and design of buildings, earthquakes resulted in around 1.8 million injuries (three times the number of fatalities) over the past two decades. Several existing PBEE-based methodologies use rudimentary models that may not accurately estimate earthquake-induced casualties. Even when models are suitable for predicting the total number of fatalities and critical injuries, they may fail to adequately differentiate between different levels of injury severity. This paper draws attention to the importance of extending the seismic casualty assessment method by broadening the perspective on injury severity. To this cause, a probabilistic model is developed to predict fatalities and injuries due to earthquakes. The proposed model adopts the FEMA P-58 framework for risk assessment and considers six injury severity levels (minor, moderate, serious, severe, critical and fatal), in accordance with the Abbreviated Injury Scale (AIS). The aforementioned framework evaluates the casualty risk with five modules: seismic hazard analysis, structural analysis and response evaluation (using incremental dynamic analysis), building collapse simulation, detailed casualty assessment caused by structural, nonstructural, and content components of the building, and injury severity assessment. The injury severity assessment module assumes two modes of injury: occupants falling on the floor resulting in injury and injuries caused by unstable building contents hitting occupants as a result of sliding or overturning. The framework uses an occupant-time location model to predict the number of injuries and a set of building content fragility curves for sliding and overturning failure modes, developed by the incremental dynamic analyses. The proposed model was applied to a case study of a reinforced concrete, moment-frame office building furnished with 21 different content objects. The results show that the frequency of injuries resulting in hospitalization can be up to 30 times more than that of the fatal injuries at low shaking intensity levels and may amplify by 20 times at high intensity shaking

StEER 2022 Mw 5.6 Indonesia Earthquake Preliminary Virtual Reconnaissance Report (PVRR)

A magnitude 5.6 earthquake occurred in West Java, Indonesia, on November 22, 2022. The epicenter of the the earthquake was in the Cimandiri Fault Zone and the depth of the rupture was approximately 11 km. While most of the damage was limited to the town of Cianjur, the shaking caused by the earthquake was felt as far as the capital city of Jakarta. The highest peak ground acceleration value recorded by the event was approximately 0.15 g at a station located approximately 14 km from the epicenter. The earthquake caused widespread damage to buildings, lifelines, and loss of human lives. The death toll from the earthquake was 310, with approximately one-third of the fatalities being children. Widespread damage to residential buildings, schools, and government buildings was reported following the earthquake. Indonesia has well-established building codes that explicitly address the issue of seismic design. However, much of the observed damage appears to have been due to non-compliance between the constructed buildings and the regulating building standards. Most of the affected structures were 1- and 2-story buildings constructed using masonry infills, some of which are surrounded by concrete frames (intended as confined masonry). In addition to building damage, the earthquake caused the disruption of several lifeline facilities, including potable water supply, power outage, and ground transportation. This project encompasses the products of StEER's response to this event, the Preliminary Virtual Reconnaissance Report (PVRR)

StEER 2022 Mw 6.1 Duzce, Turkey Earthquake Preliminary Virtual Reconnaissance Report (PVRR)

An earthquake occurred in Duzce, Turkey on Nov. 23, 2022 with magnitude of 6.1 and a depth of 10.0 km. The region has been struck by several destructive earthquakes in the past decades. The vast majority of the buildings in the region affected by the earthquake, including government and school buildings, have been either retrofitted or rebuilt after the Aug.17, 1999 Mw 7.6 Kocaeli and Nov. 12, 1999 Mw 7.2 Duzce earthquakes. No structural damage and nonstructural damage were reported in these buildings during this event. This low level of damage shows the effectiveness of retrofit measures and recent strict seismic design requirements enforced for the buildings constructed after 1999. In general, limited collapses and structural damage were observed. However, the economic losses due to nonstructural damage and business interruption were significant. There were no reports of damage to roads and bridges, and power, water, telecommunications, and other infrastructure and lifelines. This project encompasses the products of StEER’s response to this event: Preliminary Virtual Reconnaissance Report (PVRR)