Rehabilitation Of Structures Research Articles

Effect of structural uncertainties on seismic performance of moment frame rehabilitated with steel shear wall

In performance-based engineering, conservatism in acceptance criteria at structural performance levels has increased the cost of retrofitting. When simulating structure response in the presence of uncertainties, seismic demand and structural capacity cannot be expressed certainly, though the possible range of these can be predicted. In the seismic rehabilitation of structures, uncertainties have been studied on existing structures and rehabilitation guidelines have been implemented on these uncertainties by reliability index. Adding a secondary system to rehabilitate existing structure may increase uncertainties and may be effective for results of reliability. Therefore, in this study, reliability of rehabilitated a structure with steel shear wall has been discussed with the aim of quantifying uncertainties. Also, the parametric study of reliability index has been performed on probabilistic variables considered for steel shear wall. The selected structure is a three-storey structure of SAC steel moment frame, which was rehabilitated by steel shear wall. For modeling and analyzing the structure, OpenSees software was used. The structure was subject to incremental dynamic analysis before and after of rehabilitation, with probabilistic variables considered for steel shear wall.

A Case Study of Modern Heritage Building: Base Isolation Seismic Retrofit for Preservation of its Architectural Distinguishing Features

Several Italian buildings designed by eminent architects and structural engineers in the second half of the 20th century are now included in modern heritage listings. At the same time, as they were designed before the issue of coordinate national Technical Standards, often require important structural rehabilitation interventions. One of the most representative case studies of that period in Florence, i.e. the building now housing the Automobile Club Headquarter and a B&B Hotel, is examined in this paper. A seismic assessment analysis carried out on the structure highlighted strength deficiencies in several members and potentially severe pounding conditions between the two constituting wings of the building, separated by a narrow technical gap. In order to improve the seismic performance without altering the architectural appearance of the building, characterized by large windows in the façades, free internal spaces and elegant proportions of the main structural members, a base isolation retrofit hypothesis is proposed. A substantial seismic improvement is obtained in rehabilitated conditions, as assessed by the achievement of safe stress states for all members up to the basic design normative earthquake level, as well as of maximum relative lateral displacements of the two wings constrained below the technical gap width.

Strengthening of Structure by Repair, Rehabilitation, Retrofitting and Restoration

All structures have a assumed use able life, which depends on the weathering action, chemical attack, embedded metals, alkali-aggregate reactivity, fire, due to overload, seismic forces, quality of materials used, techniques, workmanship etc. The large numbers of monuments, which are cherished heritage structures have stood well over a period of time due to best material and periodical maintenance. But some of these have shown signs of distress due to age, aggressive natural environment/industrial pollution etc. Further, distress gets aggravated due to overcrowding and misuse of buildings. Some Buildings have also failed due to faulty design, construction, bad quality materials, poor workmanship etc. The various causes of structural failure and the principles of rehabilitation of structures are discussed. In the structures, the cracks are generated due to different causes e.g. in some cases cracks are caused after the structure has been completed for a few years which results in shortening of life and strength of structure. The main criteria is how to repair a reinforced concrete elements of structures and for this the skills, knowledge, and experience required to repair damaged or deteriorated structures are decidedly different from those required to build new structures. The purpose of this paper is to justify the latest techniques, advanced materials and various requirements of repairing work to obstruct the deterioration which is necessary and economical than to reconstruct the building.

Probabilistic Fling Hazard Map of India and Adjoined Regions

ABSTRACT The present work aims at developing the first probabilistic fling hazard map of India and adjoined regions. First, we developed a new ANN-based ground motion prediction equation (GMPE) for fling corresponding to horizontal and vertical directions. The developed GMPE is based on permanent ground residual displacement form 556 scenario events considered consistent with the regional characteristics. The corresponding simulations are performed by suitably combining the Okada’s solutions. Developed GMPE is comparable with the existing relations and the few available data which contained fling characteristics. Further, the developed GMPE, along with the other two available prediction equations for the fling, is incorporated to represent the ground motion characteristics in the estimation of hazard using a suitable logic tree. In addition to the fling prediction equations, the evaluation of regional fling hazards requires identifying the location of all the probable seismic sources and their seismicity characteristics. In this study, we used the linear-fault model, as the fling is a near field phenomenon. We report the resultant probabilistic fling hazard map for 10%,2% 1%, and 0.5% probability in 50 Years for the region. The maps showed that the active regions in Himalayas, North-Eastern India, and Andaman experience higher values for fling than stable Peninsular India. Thus, this study develops the fling hazard map for the first time, and the results are essential in the design and rehabilitation of important structures in the region.

Efficacy of early structured pulmonary rehabilitation program in pulmonary function, exercise capacity, and health-related quality of life for patients with post-tubercular sequelae: A pilot study

BackgroundResidual structural changes in the lung along with pulmonary impairment remain in a large number of patients of tuberculosis after microbiological cure. The aim of this study was to determine whether 12 weeks of a structured pulmonary rehabilitation program (PRP) administered along with antitubercular treatment improved the baseline measurement of pulmonary function, exercise capacity, and health-related quality of life (HRQOL). MethodsA pilot study with single blind randomized control design was carried out in a tertiary care chest center. Spirometry, exercise capacity by 6-minute walk distance (6MWD), and HRQOL using St George respiratory questionnaire (SGRQ) score were evaluated in 62 patients, divided into 2 groups: intervention group (IG) (n = 31) and control group (CG) (n = 31) patients at baseline and at end of 12 weeks. IG completed 12 weeks of PRP. ResultsSignificant difference in forced expiratory volume in 1st second (FEV1) (2.94 L at baseline vs 3.18 L at end of 12 weeks of PRP, diff 0.239 L, p-0.001), forced vital capacity (FVC) (3.43 L vs 3.75L, p −0.00), 6MWD (440.6 m vs 574.6 m, p = 0.00), and SGRQ score of at baseline (24.5 m vs 11.1m, p = 0.00) was seen in the IG. At end of 12 weeks, there was statistically significant difference in FEV1(L) (p = 0.01, 95% CI −0.317 to −0.046), FVC(L) (p = 0.00, 95% CI −0.359 to −0.139),6MWD(m) (p = 0.00; 95% CI −101.6 to −49.57) between CG and IG. There was no statistically significant difference in SGRQ scores between the 2 groups (p = 0.231). ConclusionPRP administered along with treatment is beneficial in reducing residual pulmonary impairment.

Composite patch repair of damaged tubular members from flare boom structures subjected to compressive loads

Conventional repair method for steel structures requires cutting and welding processes, which in offshore platforms may impose several disadvantages. Composite material repair has become an alternative for the rehabilitation of damaged structures and has been widely applied in other industries. In this work a numerical-experimental investigation evidences the effectiveness of the composite patch repair for flare boom corroded tubular elements subjected to axial compressive loads. A finite element model developed to determine the minimum composite laminate thickness that recovers the structural element strength is validated through numerical simulations. Twelve API 5L grade B reduced scale steel tubes with central perforations and similar longitudinal and transverse slenderness, respectively defined by length to radius of gyration of the cross-section area and diameter to thickness ratios, are tested covering the range of interest for full scale members. The composite material consists of a hybrid fabric made of carbon and glass fibers impregnated with epoxy resin. Severe localized corrosion is considered conservatively, idealized as a circular perforation in half the element length. In many cases the maximum load of the repaired tube even exceeded the intact tube capacity. Moreover, it is shown that sufficient load capacity recovery is achieved for the conditions assumed.

Prevalence of patients requiring full mouth rehabilitation classified based on turner and missirlian classification and choice of treatment outcome

To assess the prevalence of patients requiring full mouth rehabilitation based on the turner and missirlian classification and assess the choice of the treatment plan. The study was done in the institutional hospital setting of Saveetha Dental College, Chennai. Patients requiring Full mouth rehabilitation were assessed, data was obtained from filtering the college database to obtain 65 patients. The patients were classified by the Turner and Missirlian classification based on their extent of rehabilitation required and the treatment protocol used for them was also assessed. The obtained data was tabulated using an Excel sheet and statistical analysis was performed using Pearson correlation. Prevalence of Category 1 Of turner and missirlian classification was among patients above 60 years (36.8%), For category 2 it's among patients between 50-60 years (33.3%), and category III (36.4%) showed similar results as class I in terms of prevalence. The treatment preferred was mostly tooth supported FMR, Category 1 (52.6%), Category II (47.2%), Category III (54.5%). Full mouth rehabilitation involves extensive rehabilitation of oral structures requiring a meticulous interdisciplinary approach. The study shows the increased requirement of full mouth rehabilitation among elderly patients. Research analysing the prevalence of patients in need for such rehabilitation could give us a ground report on the oral health status of a population, and could prove to be valuable literature which could become the forerunner for research in analysing the treatment protocols.

Geotechnical assessment and rehabilitation of retaining structures collapsed partially due to environmental effects

The aim of this study is to provide geotechnical evaluation and structural rehabilitation proposal for an existing retaining structure. The present article covers the improvement suggestions based on the geotechnical interventions and numerical analysis after the partial collapse in the retaining structure consisting of bored piles and soil anchors during the deep foundation excavation carried out for the construction of marketplace, parking garage and educational building. In the study, (i) reasons for the collapse of retaining structure, (ii) stability conditions before and after the collapse, (iii) initial interventions to stop the collapse motions, and (iv) proposed improvements for the collapsed part and the others were presented as well as the stages of verifying these techniques with limit equilibrium and numerical analyses. It was aimed to put forward an applicable and important tool in the context of structural interventions for the collapses in retaining structures and improvements of retaining systems.

A method for bottom-up cracks healing via selective and deep microwave heating

The expected life of an asphalt road pavement depends on many factors (fatigue cracking, thermal cracking, etc). Bottom-up cracking is a common mode of hot mix asphalt pavement distress and appears to be critical. In view of this, the objectives of the study presented in this paper were confined into setting up an innovative and non-destructive method to carry out the rehabilitation of the pavement structure. In particular, a new procedure for healing in-depth damaged asphalt pavements is proposed and discussed. This method, based on selective heating, uses appropriate doping and electromagnetic fields in the microwave frequency range in order to induce the self-healing process of the material. Compared to the existing procedures, it allows a deep, selective, adaptive, and not invasive healing. The procedure, numerically validated by multi-physical simulations, can be applied to all solid structures made up of materials wherein the self-healing process can be induced by heating.

Bondline strength of glued-in threaded rods in new and ancient chestnut (Castanea sativa Mill.) wood

Glued-in rods (GIR) are being increasingly used in connections of new timber structures, complying with design rules mostly based on tests with new softwood specimens. However, the system also shows great potential for use in strengthening and rehabilitation of ancient timber structures, in which hardwoods were often used, namely in the Central and Southern European countries. Aiming at contributing to the scarce information available for these particular applications, an experimental program is carried out, consisting of the production and testing of both new and ancient chestnut timber specimens, the latter cut out from beams of demolished buildings. Given the limited number of specimens available, the bonding length was selected as the only variable parameter, although the hole diameter, the bond line thickness and others also play a relevant role on the behaviour of these connections. The relevant dimensions were set in order to preclude the steel yielding failure mode, desirable in actual applications, to favour the cohesive or adhesive failure modes at the wood-adhesive interface and the timber splitting failure mode, where most of the unanswered issues stand. All specimens were first tested with a pull-pull setup, and the unfailed sides were later tested in pull-push mode. The results were compared to the estimates provided by some of the existing design methods proposed in the literature.

Viñedos en terrazas en la región vitivinícola del Duero, Portugal: una perspectiva de la gestión del suelo y el agua

Los viñedos del Duero son un ejemplo sorprendente de protección del suelo, materializado, en un paisaje fuertemente humanizado, donde las terrazas cubren una gran parte de la región. Este trabajo tiene como objetivo presentar una perspectiva sobre las mejoras en la gestión del suelo y el agua en los viñedos en terrazas del Duero, como respuesta a las responsabilidades reales determinadas por el estatuto del Patrimonio Mundial de la UNESCO, para preservar un paisaje cultural, vivo y evolutivo. Después de enfatizar sobre la importancia de los viñedos en terrazas del Duero en el territorio continental portugués y las limitaciones naturales para la producción de cultivos que caracterizan el valle del Duero, se describen los tipos de terrazas presentes en el paisaje del Duero, junto con los cambios en el uso del suelo debido a las operaciones de las terrazas agrícolas. Además de la rehabilitación de las estructuras de piedra seca como parte de las intervenciones de preservación del patrimonio cultural de la región, las áreas de riesgo crítico en las laderas aterrazadas identificadas recientemente se identifican como una prioridad para las intervenciones de protección del suelo y gestión del agua. Se trata de las áreas de viñedos más expuestas al impacto directo de las lluvias erosivas y comprenden los pasillos entre líneas de la vid, especialmente en viñedos no aterrazados, los taludes desnudos de tierra en terrazas de origen reciente, y las redes de caminos y drenaje agrícolas, espacialmente coincidentes, en laderas empinadas plantadas extensivamente. Prácticas innovadoras de gestión del suelo y agua deben desarrollarse y probarse localmente en un diálogo cercano con los actores regionales.

Managing Dyspnea in Individuals With Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis is an unrelenting form of interstitial lung disease associated with a high symptom burden and reported low health-related quality of life. Clinicians have access to limited pharmacologic interventions to help slow the disease progression. Nonpharmacologic interventions are vital in managing dyspnea for these individuals, which is one of the most frequently reported factors that negatively impacts health-related quality of life. Common methods of symptom control include integration of pulmonary rehabilitation, supplemental oxygen, and interdisciplinary support, such as support groups, palliative care, and case conferences, into routine medical care. This literature review describes a multidisciplinary approach for managing dyspnea to improve health-related quality of life for those with idiopathic pulmonary fibrosis. Findings demonstrate that structured pulmonary rehabilitation programs, fast-track case conferences, and supplemental oxygen therapy are most effective. Further research is needed to demonstrate a clinically significant benefit of palliative care visits in the long term for these individuals.

Structural Safety and Stability of the Bridge on the Paraopeba River in Moeda, Minas Gerais, Brazil: Case Study

A railway bridge over the Paraopeba River was built in Moeda, Minas Gerais, Brazil; however, the railway line for which it was intended was deactivated and, to reuse it as a road bridge, a concrete deck was installed. Upon closer inspection, anomalies were revealed and their causes were found to be related to the installation of the new deck. This work intends to contribute to the structural evaluation and rehabilitation of steel bridges through numerical analysis. For this purpose, a three-dimensional numerical finite-element model of the structure using the SAP2000 version 15 software was developed, in which the acting loads were applied according to the Brazilian standards. The outcomes obtained by the performed nonlinear analysis indicate the occurrence of buckling due to the axial compression load in some structural elements, a phenomenon also observed during the bridge’s first inspection. Thus, to ensure that the bridge is safely reused, the locking of the truss diagonals is proposed as a structural reinforcement. Additionally, the posts’ lateral locking of the three end spans is recommended.

BRB retrofit of mid-rise soft-first-story RC moment-frame buildings with masonry infill in upper stories

A high percentage of mid-rise soft-first-story (SFS) reinforced concrete (RC) buildings with masonry infill in upper stories collapsed in Mexico City during the SEPT/19/2017 earthquake. For this reason, in this work, an SFS building with similar structural characteristics to those damaged during such an event is subjected to several ground motions recorded at different Mexico City stations. As was expected, the peak drift demands are larger in comparison with the limit recommended by the Mexico City Building Code (2004). With an aim to improve the seismic performance of the building, three structural rehabilitation solutions are proposed and discussed. Then the seismic performance of the original building and the three rehabilitation solutions are compared via incremental dynamic analysis and structural fragility in terms of peak drifts. Among the three alternative solutions, it is shown that adding buckling restrained braces (BRBs) at the SFS of the building is a technique that leads to a structural fragility similar to that obtained when using a traditional rehabilitation technique; furthermore, when the BRB core area is reduced to an acceptable dimension, the forces transmitted to the foundation become lower, leading to an even better rehabilitation solution.

PREFACE

The Fourth International Conference on Civil Engineering Research (ICCER) is a biannual international conference hosted by Department of Civil Engineering of Sepuluh Nopember Institute of Technology with the theme of Towards a Safe and Sustainable Construction using Advanced Materials and Technology for Structural Failures Prevention, Rehabilitation, and Retrofitting. Departing from the theme, variety of topics related are presented by five keynote speakers to address the common challenges in building and infrastructure development as well as critical assessments which are interrelated with technological advancement both in materials and structures.With the world facing unprecedented global CoVid-19 pandemic which is still undergoing and ramping up considerably, however, it is not possible–if not too risky–to hold an international conference in a conventional way. Gathering keynote speakers, presenters, and participants from around the world are considered harmful as it would trigger a higher possibility of people getting imposed by the Coronavirus. The situation is also exacerbated by the current travel restrictions applied by the majority of the countries which hence prevent the participants, either local or international, to travel from their origin country or region. Given that the situation of CoVid-19 in Indonesia and beyond is still uncertain with the cases growing drastically and not showing any sign of decreasing shortly, the possibility of the face-to-face conference is extremely low even when being postponed at later dates. Also, pressing the conference on hold by an uncertain amount of time would have knock-on effects on the upcoming ICCER conferences in the future. Therefore, it is of sensible (right) call that we organise this year Fourth ICCER in a virtual format.The Fourth ICCER was held in two days on exact dates of 22 to 23 July 2020. It was run virtually from the server of the Department of Civil Engineering at Sepuluh Nopember Institute of Technology in Surabaya, Indonesia, a similar location as of the organising committee. The technology used to deliver the conference was license ‘Zoom Video Conferencing’ software which was personally preferred due to comprehensive tools and user-friendly interface. Accordingly, Zoom is also known as the leader in modern enterprise video communications, with an easy and reliable cloud-based platform for video and audio conferencing, thereby making it suitable for the optimised virtual conference that the organising committee envisaged.In the Fourth ICCER, a total of 174 participants were sighted on Zoom with 94 identified as authors, whilst 80 recognised as the audience. The location of participants varied with the majority was from Indonesia, while others were from the United Kingdom, Thailand, Japan, Malaysia, Australia, and Prague. The conference model was generally similar to that of the conventional (face-to-face) method where there was an opening ceremony, sponsorship sessions, keynote sessions, plenary sessions, and a closing ceremony. In keynote sessions, the typical time allocated for keynote speaker was 60 minutes for presentation followed by 30 minutes for question and answer (Q&A) session. In plenary (parallel) sessions, 15 virtual rooms (links) were provided; each of which was detailed with information of scheduled presentations which typically consisted of 9 authors/presenters. Each presenter was given 10 minutes to disseminate their research with the video and screen share on as a means of drawing people attention, thereby creating a more active virtual environment. After the presentation, a 5-minute Q&A session was led by the moderator of the room in which all the questions from the audience were read from the chatbox. For more information on the technical quality and success of delivery of the virtual conference, please visit our website (iccer.ce.its.ac.id).Last but not least, please allow us to thank you all for participating in the ICCER conference. Despite organising in a virtual format, we hope that the essence of this conference is much as similar in many respects as the conventional conference.With kind regardsChair of Organising CommitteeProf Priyo SuproboSepuluh Nopember Institute of Technology, Indonesia

Probabilistic seismic loss estimation of aging highway bridges subjected to multiple earthquake events

This study investigates the seismic life-cycle cost of aging highway bridges under chloride exposure when subjected to multiple main shock earthquake events along the design lifetime of the structure. While chloride induced corrosion manifests as a continuous deterioration process, earthquake occurrences are typically intermittent. Although relatively weak seismic events that induce none-to-minor bridge damage may not instigate immediate intervention and repair, resulting structural cracks may further accelerate the corrosion process. This study presents a novel Monte Carlo based methodology that explicitly considers potentially altered deterioration pattern between seismic shocks as well as uncertainty in earthquake occurrences, record-to-record variability, repair decisions and repair processes for seismic life-cycle cost computations. The proposed framework also eliminates the need for the often improbable assumption in past literature on seismic life-cycle cost assessment that necessitates structural rehabilitation to pre-hazard states regardless of the seismic damage level. Case-study application of the proposed framework is demonstrated on a single column integral bridge located in the marine splash zone in California, United States. Results from multiple main shock analysis of both non-deteriorating and aging case-study bridge reveals a significant contribution of cumulative damage from corrosion deterioration and shock sequences towards seismic loss and life-cycle cost assessment.

Experimental and Analytical Studies on Harden Properties of Cement Composite Using Different Fibres

Cement composites are the most used composites in the world. In modern day construction practice, repair and rehabilitation of structures has taken an important role. The brittleness of cement composites can be reduced by reinforcing it with fibres for better shear and flexural behaviour of composites. This research work targets n experimental and analytical evaluation of the mechanical properties of fibre reinforced cement-sand composites. The effect of fibres on Compressive strength, Shear Strength and flexural strength were analysed. According to the results of this study, certain amount of fibres enhances the mechanical properties of the fibre reinforced cement-sand composites.

A New Method for Drawing the Capacity Spectrum for Seismic Analysis and Structural Rehabilitation

A review of previous studies shows that there are two general views on how to determine demand in structures through incremental nonlinear static analysis. In the first view, multi-modal methods are used to determine demand in structures. In this view, the applied load pattern is applied to the structure according to the shape of each vibration mode, assuming that the structure deformation follows the shape of the vibration mode, the capacity spectrum is drawn and after determining the target displacement and the corresponding demand for each vibration mode, the final demand is determined by combination of response modes. In the second view, structural analysis is performed as a single run nonlinear static analysis and the effect of different vibration modes is shown in one load pattern. In this method, the load pattern that has somehow the effect of different modes is applied to the structure and the structure is analyzed under this load pattern. In the second view, due to the non-conformity of the structure deformation and the lateral load of a particular vibration mode of the structure, the conventional capacity spectrum method cannot be used. Therefore, the purpose of this paper is to propose a method for drawing the capacity spectrum and determining the target displacement in single run nonlinear static analysis for non-adaptive load patterns. After presenting the equations, three frames including 3-storey, 9-storey and 20-storey frames have been selected and the results of the proposed method have been evaluated along with modal pushover method and time history analysis for the frames. Comparison of the results of the proposed method and the modal pushover with the results of the nonlinear time history analysis shows that the proposed method is more efficient in determining the lateral displacement of the stories and roof than the conventional modal pushover method.

Effect of Seawater on Micro-Nano Air Bubbles Concrete for Repair of Coastal Structures

This paper investigated the effects of seawater curing of concrete made by Micro-Nano Air Bubbles (MNAB) on compressive, flexural and tensile strengths of the concrete. This product will be applicable for rehabilitation or repair of coastal RC structures. In this research, the effect of different combinations of concrete ingredients including 0-100, 25-75, 50-50, 75-25, and 100-0 percent seawater and MNAB, respectively, on compressive strength of concrete was investigated. A total of 93 specimens were experimentally examined to study the compressive, flexural and tensile strength of MNBA concrete (MNABC) through ASTM Standard for cube, cylinder, and beam samples. The samples were cured for 1, 7, 28 and 90 days. Results revealed that MNABC cured in seawater had about 30 % higher compressive strength at ages 7 and 28 days, but it decreased in longer periods. The flexural strength of MNABC slightly increased, about 6%, after 28 days of curing in seawater. In general, the mechanical properties of MNABC at an early age revealed a considerable increase, whereas, in the longer period of time, they were decreased gradually.

Comparison between Design Formulations and Numerical Results for In-Plane FRCM-Strengthened Masonry Walls

Strengthening strategies and structural rehabilitation of existing buildings with innovative materials and techniques are today one of the main activities in the field of structural engineering. Externally bonded Fiber Reinforced Cementitious Matrix (FRCM), materials are spreading as an alternative strengthening technique to the more traditional Fiber Reinforced Polymer (FRP) ones, especially for masonry elements. This research focuses on the assessment of the shear strength of in-plane FRCM-strengthened masonry walls by means of code predictions and numerical results, with particular attention on the interpretation of diagonal compression tests simulated by means of Finite Element (FE) models. Firstly, the various approaches commonly adopted for the interpretation of diagonal compression tests in terms of shear strength were examined, since codes give generally provisions in terms of maximum shear force, while several experimental and numerical results of diagonal compression tests are available in literature. Then, the numerical simulations of diagonal compression tests obtained by several FE analyses in a previous work were examined in light of these different approaches; the corresponding predictions of the shear force are compared with code indications in order to individuate the most reliable approach both for the un-strengthened and the FRCM-strengthened walls. For the latter ones, a detailed analysis of the actual strain levels in the reinforcement was carried out, too, by means of FE analysis.