Vulnerability Assessment Of Structures Research Articles

Structural vulnerability assessment of masonry churches supported by user-reported data and modern Internet of Things (IoT)

The seismic vulnerability and damage assessment of heritage buildings at the regional scale can be considered a complex measurement problem that has suggested the development of specific multi-level procedures based on the inventory and classification of typological, constructive features, vulnerability parameters, potential or existing damage. Ancient masonry churches represent a particularly vulnerable architectural typology and the experience progressively acquired during post–earthquake observations have pointed out that recurrent damage patterns and main failure mechanisms can be identified by separately looking at the different architectural “macro–elements”, through on-site surveys. In the last few years, the macro-element approach has been extensively and fruitfully applied to perform preliminary vulnerability assessments, by recognizing the correspondence between each structural macro-element and the most recurrent collapse mechanisms associated. This paper deals with the measurement problem of damages to evaluate seismic vulnerability of historical masonry buildings. To this aim an information system is proposed consisting of a computer platform (named Quality Detection Platform - QDP) and a mobile device dedicated for data acquisition supported by Internet of Things (IoT) technology. The QDP evaluates a vulnerability index by using the macro-element approach and the Analytic Hierarchy Process (AHP) is used to improve the interpretations of the obtained measures and calibrate the relative importance of the kinematic and static criteria and automatically assign the weight to each mechanism.

A modified approach for semi-quantitative estimation of physical vulnerability of buildings exposed to different landslide intensity scenarios

ABSTRACTLandslides are the most common natural disasters in mountainous regions, being responsible for significant loss of life as well as damage to critical infrastructure and properties. As the world population grows, people tend to move to higher locations to construct buildings, thereby making structures vulnerable due to landslides. This paper discusses previous research on the vulnerability assessment of structures exposed to landslides and presents a modified semi-quantitative approach to assess the scenario-based physical vulnerability of buildings based on their resistance ability and landslide intensity. Resistance ability is determined by integrating expert knowledge-based resistance factors assigned to five primary building parameters. Landslide intensity matrix defining different intensity levels is proposed based on combinations of landslide velocity and volume. Physical vulnerability of buildings is estimated and classified as class I, II or III for scenario-based low to very high landslide intensity. Finally, the application of the model is illustrated with a case study of 71 buildings from Garhwal Himalayas, India.

Effect of 3D models on seismic vulnerability assessment of deficient RC frame structures

ABSTRACT Earthquakes pose critical danger for seismically deficient structures. This phenomenon becomes more pronounced in underdeveloped countries where such structures are common. 2D analysis of such structures can yield reasonable results but requires very careful definition of joint constraints. However, possible shortcoming of 2D analysis is that it does not cater to the relative displacement effects of the transverse members to longitudinal, which is reasonably accommodated in 3D models. This research aims to differentiate the seismic vulnerability assessment of 2D and 3D structural models. Typical deficient three-, five- and eight-storey reinforced concrete buildings constructed in Pakistan were selected as case study and modelled as 2D and 3D structures. Static cyclic analysis was performed and seismic vulnerability assessment was carried out using the capacity spectrum method. The results are then compared with the standard Global Earthquake Safety Initiative curve for deficient structures. It is observed that 3D models are brittle, crack earlier and are more vulnerable seismically compared to their 2D counterparts. It is also concluded that 2D models are more conservative compared to 3D models in terms of seismic response.

Vulnerability Assessment of Steel Structures in District 12 of Mashhad City and Prioritizing the Welding Defects Using the Analytic Hierarchy Process

Recently, steel structures have been accounted for a large percentage of the buildings due to their advantages such as higher execution speed and easier construction. In steel structures, welded joints are commonly used and their quality plays a key role in stability of buildings under applied loads. Hence, to increase resiliency of welded steel structures against natural hazards, welded joints quality should be improved. In this article, a statistical study was done on welding defects of different connections in 50 welded steel buildings that were being constructed in district 12 (Mashhad, Iran). The reasons for selecting this district were high rates of construction and high potential of hazards. Actually, initial information about joints importance and weld defects were collected by distributed questionnaires among building designer engineers and weld inspectors. In this paper, we used the Expert Choice software that works according to Analytic Hierarchy Process (AHP) to prioritize weld defects in different connections of the buildings and define management solutions to improve them. The priority results revealed that in the non-rigid connections crater, slag inclusion and spatter are more critical whereas in the rigid connections Lack of Penetration (LoP) and Lack of Fusion (LoF) are more critical than the other welding defects in steel building structures.

Metodología para la evaluación preliminar de la vulnerabilidad sísmica estructural de puentes de hormigón armado

Durante eventos sísmicos fuertes muchos puentes de hormigón armado han colapsado o han sido severamente dañados causando pérdidas humanas y materiales. Se presenta una metodología para la evaluación preliminar de la vulnerabilidad sísmica estructural de puentes de hormigón armado, que garantiza la estimación adecuada de este parámetro cuando no existe suficiente información de proyecto. Se valida a partir del método de consulta de expertos Delphi, con la participación de profesionales de diversos países seleccionados por su experiencia en el tema tratado. Se obtiene una herramienta de evaluación que incluye parámetros no utilizados usualmente en las metodologías existentes y que involucra el chequeo del período de vibración de la estructura como indicador de su comportamiento global. Finalmente se presenta su aplicación en la evaluación de 18 estructuras ubicadas en la zona de mayor peligro sísmico de Cuba.

Power System Structural Vulnerability Assessment Based on an Improved Maximum Flow Approach

With the increasing complexity of the power grid and the concerns on major blackouts, there is an urgent need for an efficient and effective tool to assess the power system structural vulnerability. To tackle this challenge, this paper proposes a maximum flow-based complex network approach to identify the critical lines in a system. The proposed method consists of two major steps. First, the power network is modeled as a graph with edges (transmission lines, transformers, etc.) and nodes (buses, substations, etc.). The critical scenarios are identified by using the principal component analysis and convex hull. Then the second step is to use an improved maximum flow-based complex network approach for topology analysis. Weighted vertices in the network are considered, enabling taking the selected operating conditions into consideration when identifying the vulnerable lines. The proposed method is validated using the western Danish power system. The vulnerable lines in the network are ranked. Simulation results demonstrate the effectiveness of the method by intentional attacks and comparison with the planning strategy from the system operator.

Seismic Vulnerability Assessment of Coupled Wall RC Structures

Seismic Vulnerability Assessment of Coupled Wall RC Structures

A Post-Disaster Functional Asset Value Index for School Buildings

Abstract School buildings must be resilient during hazardous events like earthquakes so that the important functions of the school will not be affected. During disasters, schools have an added value and important function in post-disaster activities. Schools are often used as evacuation centers. When schools are damaged, the school’s mission of continuous delivery of education will be disrupted. Due to the inadequate number of structures in our country which are intended for evacuation during disasters, schools have been used in some cases as evacuation centers, again disrupting the school’s operations. To assure that school buildings will be operational in times of disaster, structural vulnerability assessment and appropriate retrofitting must be carried out. Due to budgetary constraints in most schools, a prioritization scheme must be devised to identify the buildings that must be given immediate attention. A rapid visual screening on the structural vulnerability due to earthquake hazards can be done and then rank the buildings for more detailed inspection and retrofitting. To refine the screening and ranking, the functional asset value of the buildings can be used as a second criterion. In a post-disaster scenario, school buildings have two important functional asset values: (a) Educational Functional Value and (b) Emergency Functional Value. The educational function focuses on “continuous learning” and consists of continuous conduct of classes, preservation of school records and documents for future use, and availability of basic resources and access to basic facilities. Emergency function focuses on “protecting lives” and consists of post-disaster uses of the school such as an evacuation center, storage of relief goods and an operation center. This study aims to develop a method of assigning an index corresponding to a school building’s post-disaster functional asset value using the Analytical Hierarchy Process (AHP) and an expert’s survey. Moreover, using the two-level vulnerability screening as a prioritization scheme, decision makers can prioritize the buildings that have high seismic risk and high functional asset value. This methodology was applied on a school campus as a case study.

PROGRESSIVE COLLAPSE ANALYSIS OF 2-D RC FRAMES USING AEM

Numerical simulation of a progressive collapse of structures using computer has a very actual apprehension for structural engineers due to their interest in structures veracity estimation. This simulation helps engineers to develop methods for increasing or decreasing the progressive failure. Finite Element Method (FEM) is the most computer simulation analysis currently used to perform a structural vulnerability assessment. Unfortunately, FEM is not able to automatically analyze a structure after element separation and collision which has a great effect on a structure’s performance during collapse. For instances, a bombing load can cause damage to a main supporting column in a structure, which will cause debris flying at a very high velocity from the damaged column. This debris can cause another local failure in another column upon impact and lead to the progressive collapse of the whole structure. A new simulation technique, which was developed in 1995 as part of Tagel-Din’s doctoral research, called Applied Element Method (AEM) can simulate the structure’s behaviour from zero loading until collapse, through the elastic phase, opening and propagation of cracks, yielding of reinforcement bars and separation and collision of elements. This method is used in Extreme Loading for Structures software (ELS) by Applied Science International (ASI). In the current paper, a brief description of the AEM is given. Also, numerical modelling based on two experimental studies available in the literature conducted by Ahmadi et al. [1] and Yi et al. [2] are generated using ELS. These models are used to confirm the capability of AEM in simulation the progressive collapse behaviour of structures. Also, the models are utilized to examine and measure the structural resisting mechanisms of reinforced concrete structures against progressive collapse. The obtained numerical results indicated that, ELS can accurately model all structural behaviour stages up to collapse. A better agreement between the experimental and numerical results is observed. Moreover, the results obtained with ELS indicated an enhanced agreement with other software packages such as; OpenSees, Ansys, Abacus, and MSC Marc.

Seismic fragility analysis in the probabilistic performance-based earthquake engineering framework: an overview

The numerical analysis based seismic fragility analysis (SFA) has been emerged as an integrated platform for seismic safety assessment of structures in future earthquake scenario in the context of performance based earthquake engineering (PBEE). The approach is becoming more and more acceptable mean for seismic vulnerability assessment of structures. The present article attempts to provide an overview of the related developments on numerical simulation based SFA in the probabilistic PBEE framework. In view of the general trend on the progress of such SFA, the related developments are presented under two subheads: (1) the analytical SFA based on probabilistic seismic demand and capacity models and (2) the statistical simulation based SFA based on non-linear PBEE using random field theory and statistical simulation. In doing so, considering the importance of the application of Bayesian approach in SFA, it has also been discussed separately. Finally, critical observations on the developments and scope of study to progress the state-of-the-art are summarized.

Mine blast vibration response spectrum for structural vulnerability assessment: case study of heritage masonry buildings

ABSTRACTGround-borne vibrations induced by mine blasting are typically of low amplitudes, which are not considered a major concern for modern engineered structures. However, historic structures are often considered more vulnerable due to inadequate knowledge regarding the state of construction materials and structural response. Specifically, the construction materials used might be fragile or have deteriorated to a stage that could be vulnerable to such vibrations. Simplistic rule based on peak ground motion parameter has been adopted worldwide for safety assessment, while the frequency characteristics of vibrations are not taken into account. Further, there is very limited study on response of heritage structures to near-field blasting. This article presents a practical structural vulnerability assessment method for mine blast-induced vibrations. In particular, a design response spectrum model is proposed based on close range measurements of nearby mine blasting, which is compared with an existing design spectrum model for far-field mine blasts and a typical design spectrum model for earthquake actions. The method is illustrated through a case study of heritage masonry buildings in Australia. The unique blast data presented and the generalized methodology would be useful to both structural engineers and blast engineers in considering potential effects of blasting on heritage structures.

Seismic Demand for Low-Rise Reinforced Concrete Buildings of Islamabad–Rawalpindi Region (Pakistan)

Determination of appropriate seismic demand is important for deriving reliable seismic forces for use in structural design and vulnerability assessment. Demand can be defined by either probabilistic or deterministic approaches depending on the use of the assessment. The use of probabilistic or deterministic approaches depends on the level of the assessment since deterministic can mostly be used for single structures whereas probabilistic for city or country level assessment. This paper presents demand characterization which is based on results of existing seismic hazard studies and local tectonic features around Islamabad–Rawalpindi region (study region) in Pakistan. Existing seismic zoning maps and recent probabilistic seismic hazard studies are reviewed, and the findings are used to quantify and compare the demand for a typical low-rise reinforced concrete building. As another option, deterministic demand is defined through spectra using suitable attenuation relationship which is assessed and validated using the Kashmir earthquake and other similar earthquakes data. Deterministic spectra for study region are generated by considering the critical local tectonic features. Federal Emergency Management Agency (FEMA 356) approach is used for smoothening of deterministic spectra, and the new spectral corner periods are calculated.

Experimental Investigation of Bond Characteristics of Deformed and Plain Bars in Low Strength Concrete

The use of inferior quality materials, inadequate detailing and poor construction practices are responsible for most of the brittle failure modes of non-engineered reinforced concrete structures. Bond failures in non-engineered reinforced concrete elements due to short anchorages or low concrete cover result in large slip deformations prevent the development of plastic deformations and reduce energy dissipation capacity. Until now, little work has been carried out that can lead to the development of bond-slip relationships for low strength non-engineered reinforced concrete structures. To address this, experiments have been carried out on pullout and splitting specimens under monotonic loading to investigate bond characteristics of typically used steel bars in non-engineered reinforced concrete structures. Various deficient parameters are considered in the experiments in order to develop multi-parameter bond strength relations for low strength concrete ≤15MPa. The key parameters examined in the experiments are low strength concrete, bar development length, concrete cover, re-bar types (deformed and plain) and re-bar diameter. This paper presents the experimental details and results which are further processed to develop bond strength equations for different bar types in low strength concrete. These equations can be used to define the bond-slip relation for conducting seismic vulnerability assessment of non-engineered structures.

Framework for the vulnerability assessment of structure under mainshock-aftershock sequences

Many earthquakes have indicated that the mainshock-damaged structures may be more vulnerable to severe damage and collapse during the subsequent aftershocks. This manuscript presents a framework for the vulnerability assessment of structure under the mainshock-aftershock sequences. In this framework, the engineering demand parameter (EDP) which can more effectively characterized the additional damage of structure induced by aftershock, and the intensity measure (IM) having the higher correlation with the additional damage of structure are selected and used. The versatility of the proposed framework is demonstrated on a case-study reinforced concrete (RC) frame structure with 5 stories. The influences of aftershocks on the fragility of structure are studied for different limit states. The effects of aftershocks on the fragility of structure are more obvious for the case that mainshock fragility changes from 30% to 60%, and the maximum influence of aftershock can exceed 15%. The results in this study can be used to evaluate the vulnerability of structure under the seismic sequence in the pre-earthquake environment.

Картографирование структуры изолированных энергосистем (на примере Камчатского края, Магаданской и Сахалинской областей)

The article describes a way to represent the structure of the energy system using an undirected weighted graph. It also considers the concept of structural vulnerability of the electrical grid as a key property affecting the reliability of power supply. We consider isolated energy systems of the Russian Far East, taking into account the differentiation in structural vulnerability within the networks of different types. For these purposes we propose the technique of designing and using geodatabase for the structural vulnerability assessment in the territories of the Kamchatka Territory, Magadan and Sakhalin regions. The designed technique is based on the use of open source data about power transmission lines (PTL), substations and power plants. Remote sensing data was also used. It is introduced a principle of zoning study area based on geoprocessing model. These maps were compared with some maps of crucial climatic parameters such as maximum wind speed and sleet deposits wall thickness.

Pseudo-Separation for Assessment of Structural Vulnerability of a Network

Based upon the idea that network functionality is impaired if two nodes in a network are sufficiently separated in terms of a given metric, we introduce two combinatorial pseudocut problems generalizing the classical min-cut and multi-cut problems. We expect the pseudocut problems will find broad relevance to the study of network reliability. We comprehensively analyze the computational complexity of the pseudocut problems and provide three approximation algorithms for these problems. Motivated by applications in communication networks with strict Quality-of-Service (QoS) requirements, we demonstrate the utility of the pseudocut problems by proposing a targeted vulnerability assessment for the structure of communication networks using QoS metrics; we perform experimental evaluations of our proposed approximation algorithms in this context.

Complex Networks Theory For Modern Smart Grid Applications: A Survey

This paper provides a survey of studying complex network theory for modern smart grid applications. A brief overview of complex network theory will be explored first. Topological characteristics, statistic characteristics, such as self-organized criticality and critically slow down, and dynamical characteristics, including synchronizations, consensus control, and pinning control, will be briefly addressed. Then, we will illustrate how complex network theory can be applied to modern smart grids in structural vulnerability assessment, cascading blackouts, grid synchronization, network reconfigurations, distributed droop control, pinning control for micro-grid autonomous operations, and effective grid expansions. Some emerging topics and future perspectives are also addressed.

Seismic Failure Probability and Vulnerability Assessment of Steel-Concrete Composite Structures

Building collapse in earthquakes caused huge losses, both in human and economic terms. To assess the risk posed by using the composite members, this paper investigates seismic failure probability and vulnerability assessment of steel-concrete composite structures constituted by rectangular concrete filled steel tube (RCFT) columns and steel beams. To enable numerical simulation of RCFT-structure, the details of components modeling are developed using OpenSEES finite element analysis package and the validation of proposed procedure is investigated through comparisons with available experimental results. The seismic fragility and vulnerability curves of RCFT-structures are created through nonlinear dynamic analysis using an appropriate suite of ground motions for seismic loss assessment. These curves developed for three-, six- and nine-story prototypes of RCFT-structure. Fragility curves are an appropriate tool for representing the seismic failure probabilities and vulnerability curves demonstrate a probability of exceeding loss to a measure of ground motion intensity.

Structural Vulnerability Assessment of Historical Buildings in Turkey

Structural Vulnerability assessment of historical buildings is very important to carry them to the future. Turkey is a rich country in terms of historic masterships mostly from Ottoman Empire, such as mosques, bathhouses, churches and aqueducts. Especially mosques are the common historical structures in turkey. Therefore, in the present study, structural vulnerability assessment of historical mosques in Turkey was carried out. One of the existing ones is considered as a sample building and structural vulnerability assessment was carried out on this building. The sample building was selected as Konak Mosque located in Izmir, Turkey. The mosque was structurally investigated through advanced approaches. The mosque, constructed in 1755 by Ottoman at very central location close by the clock tower, is little one decorated with blue tiles. The mosque is also nearby a historical bazaar where the main historical business stream line is located. Konak Mosque is one of these new styles in that age. It can be named as a signature historical building representing Islamic minimalist oriented architecture with its unique octagonal plan. In the present study, the building was modelled by using the Finite Element Modelling (FEM) software, SAP2000. Time history analyses were carried out using 10 different ground motion data. Displacements, base shear and stress values were interpreted and the results were displayed graphically and discussed. For probabilistic seismic risk assessment, fragility analyses were also carried out and the fragility curve and surface were sketched for the mosque. Saddle point was determined on the fragility surface.

Vulnerability Assessment of Coastal Structure: A Case Study on Light Houses

Lighthouses are the road signs of the ocean. They guide sailors through dangerous waters. Each lighthouse design is based on the land it is built on, its purpose, and the technology available. The Geometry of the lighthouses is round, square, octagonal, or conical in shape. These lighthouses need to be in operation 24 × 7 guiding the ships coming towards the coast. However, these lighthouses got affected during past earthquakes. The main objective of this work is to perform the nonlinear time history analysis of Navadra, Kachchigadh and Dwaraka point lighthouses subjected to eight ground motions. Since most of the Gujarat state is under Zone-III, IV and V, the analysis is carried out by normalizing them to respective zone factors as suggested by Bureau of Indian Standards IS 1893 (part-1): 2002. Using energy dissipation approach, damage is quantified at every displacement level. A fragility curve has been developed to quantify the damage of the above lighthouses with respect to different peak ground accelerations. Based on the fragility analysis of lighthouses, the following conclusions are drawn. It is concluded that the damage of the Navadra lighthouse at Mandi, Jodiya and Jhangi is 0.2, 0.08 and 0.68 respectively.