thesis about vulnerability seismic

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Thesis about vulnerability seismic popular dissertation chapter editing websites usa

Thesis about vulnerability seismic

Ind Constr 66— Google Scholar. Proposta per una metodologia e risultati preliminari. Nat Hazards — Cardona, O. PhD Thesis, Barcelona, Spain. Wiley, Chichester, England. Book Google Scholar. Madrid, pp — Corsanego A, Petrini V Seismic vulnerability of buildings. Trieste, Italy. Calvi GM A displacement-based approach for vulnerability evaluation of classes of buildings.

J Earthq Eng 3 3 : — Cahier technique AFPS Technical Report 10th european conference on earthquake engineering. Vienna, No. International workshop on seismic risk and earthquake damage scenarios of potenza. Eng Struct — Fajfar P Capacity spectrum method based on inelastic demand spectra. Earthq Eng Struct Dyn — Gruppo Nazionale per la Difesa dai Terremoti: Roma. Giovinazzi S, Lagomarsino S A macroseismic model for the vulnerability assessment of buildings.

In: Proceedings of 13th world conference on earthquake engineering. Vancouver: Canada. Giovinazzi S The vulnerability assessment and damage scenario in seismic risk analysis. Atti del Convegno, Udine, 14—15 Novembro. In: Proceedings of the 4th Italian conference on earthquake engineering, Milano I, pp — Lang K, Bachmann H On the seismic vulnerability of existing unreinforced masonry buildings.

J Earthq Eng 7 3 : — Lagomarsino S, Giovinazzi S Macroseismic and mechanical models for the vulnerability assessment of current buildings. Bull Earthquake Eng. Eng Geolog 45— Di Pasquale G, Goretti A Economic and functional vulnerability of residential buildings stricken by Italian recent seismic events.

In: Proceedings of the 10th Italian national conference on earthquake engineering in Italian. Speranza E An integrated method for the assessment of the seismic vulnerability of historic buildings. PhD Thesis. University of Bath. In: Proceedings of the 10th European conference on earthquake engineering, vol 3, pp — Tiedemann H Casualties as a function of building quality and earthquake intensity.

In: Proceedings of the international workshop on earthquake injury epidemiology for mitigation and response; 10—12 July, Baltimore, Maryland. Johns Hopkins University, Baltimore, pp — UNDP, Vienna. Vicente RS Strategies and methodologies for urban rehabilitation interventions. The vulnerability assessment and risk evaluation of the old city centre of Coimbra. In: Proceedings of the international conference th anniversary of the Lisbon earthquake, 1st—4th November, pp — The methodology is based on an optimum utilization of high resolution satellite data and a Stratified Random Sample Survey.

Ten different classes of socio-economic clusters found in Indian cities are defined and 34 Model Building Types MBTs prevalent on the Indian subcontinent have been identified. Two analytical models, based on equivalent frame approach, are presented, which automatically simulate the effect ofvariation ofaxial forces in piers. The models have been validated for results of two walls, studied in the 'Catania Project'.

An exercise has also been carried outto select representative building plans based onthe statistical analysis of plans of 32 buildings selected randomly from field survey. The seismic behaviour of the representative buildings has been simulated using one of the proposed models and Capacity Spectra have been developed for URM buildings, in mud, lime and cement mortars, representing typical north Indian construction.

The damage predicted by the analytical simulation is higher than that predicted by PSI scale, but lower than that observed during Bhuj earthquake. The developed methodology is demonstrated through a case study of a typical north Indian city of Dehradun, located in the foothills of Himalayas. The risk estimates using the two sets of DPMs, have been compared. At moderate intensities, the two estimates are in fair agreement, but, at lowand high intensities, the estimates based on PSI scale are more reasonable as the descriptive scales saturate at these intensities.

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Each expert was asked to fill a comprehensive questionnaire by utilizing their best knowledge ATC- 13 Another such approach, applicable to both masonry and R. M and was applied to Catania City. The methodology was aimed at developing a procedure for evaluating the seismic performance of existing building in order to identify hazardous buildings that can impose risk to human lives. The structural stability of traditional buildings was studied and simple improvements were assessed.

Risk mitigation strategies were developed based on detailed surveys carried out in Jhatapol on the edge of the world heritage area of Patan Durbar Square monument zone. The understanding derived from the study carried out in the limited area of Jhatapol must be extrapolated to all the historic urban areas within the Kathmandu valley Final Report of the Kathmandu Research Project Fragility functions or curves are extremely important for estimating the overall risk to the civil infrastructure from potential earthquake.

The elements of the seismic response of building can be obtained either analytically analytical fragility curves or obtained through empirical data collection and evaluation spotting sizes empirical fragility curves P. Unreinforced Masonry Bearing Wall URM building has been sub classified into low-rise 1 to 2 storey or up to 15 feet high and mid-rise 3 storey above or 35 feet high.

In most cases floor and roof construction consists of wood sheathing supported by wood framing. Wood floors usually have plywood rather than board sheathing. The walls may or may not be anchored to the diaphragms. Ties between the walls and diaphragms are more common for the bearing walls than for walls that are parallel to the floor framing. Roof ties usually are less common and more erratically spaced than those at the floor levels. Interior partitions that interconnect the floors and roof can reduce diaphragm displacements.

The extent and severity of damage to structural and nonstructural components of a building is described by one of five damage states: None, Slight, Moderate, Extensive, and Complete. Some parapets and gable end walls have fallen.

Beams or trusses may have moved relative to their supports. The probability of being in or exceeding a given damage state is modeled as a cumulative lognormal distribution. A procedure for rapid visual screening RVS was first proposed in the US in , which was further modified in to incorporate latest technological advancements and lessons from earthquake disasters in the s.

This RVS procedure, even though originally developed for typical constructions in the US have been widely used in many other countries after suitable modifications. The most important feature of this procedure is that it permits vulnerability assessment based on walk-around of the building by a trained evaluator.

It provides nationally applicable methodology for estimating potential earthquake losses on a regional basis. FEMA results develop a list of potentially hazardous buildings whereas the result of HAZUS estimate the loss of functionality for specific buildings. This type of analysis is used to determine the dynamic response of a structure to arbitrary loading.

Time-history analysis is performed at discrete time steps. The number of output time steps are specified with parameter n step and the size of the time steps with parameter dt. The time span over which the analysis is carried out is given by n step, dt. One time history load case involves thousands of equations to solve. While running dynamic analysis, SAP performs modal analysis to determine the un-damped free vibration mode shapes and frequencies of the system Qaiser In order to carry out dynamic analyses, an appropriate set of acceleration time histories is required.

Among the categories of available ground motion records artificial accelerograms, synthetic accelerograms, real records [e. Acevedo ] , real accelerograms are more advantageous to use, since they are genuine records of ground shaking from earthquakes. Therefore they include all the ground motion characteristics, such as amplitude, frequency content, duration, and reflect the influence of source, path and site characteristics on accelerograms Ilaria A sufficient number of ground motion records has to be used in the analyses, since it is well established that the inelastic response of structures in sensitive to the characteristics of the input motion Bazzurro, et al.

According to several modern seismic codes, UBC, ; OPCM , ; OPCM , ; EN , ; NTC08, and as supported by research works Bommer, Acevedo and Douglas , if the response is obtained from at least seven nonlinear time history analyses with spectrum-compatible ground motions, the average of the response quantities from all analyses should be used as design value of seismic action effect.

Otherwise, the most unfavorable value of response quantity among the analyses should be used. According to Bommer, Acevedo and Douglas , linear scaling of the amplitude of records is acceptable, in particular for those records of earthquakes with similar magnitude to that of the earthquake scenario, since the shape of response spectrum is not highly sensitive to distance.

The study area has been divided into three blocks namely A, B and C. In total buildings were surveyed out of which buildings were brick masonry. The survey location map and the study area is shown in fig. The main purpose of structural survey of the building was to record the structural condition of the buildings. Buildings information such as, building type, uses, numbers of storey, modifications, damage in foundation, structural condition of wall and material deterioration in walls were recorded in building checklist format, from which data for various methods of RVS could be collected.

Five buildings were selected as building typologies representing the traditional brick masonry buildings of the study area Parajul, Maskey and Taniguchi Plans and sections of representative buildings are shown in fig. Final Structural Score S all relate to the probability of building collapse.

Final score, S typically range from 0 to 7. Building receiving lower score are determined as potential risk. Figure 4. The damage classifications based on the European Macroseismic Scale G. Grunthal define building damage to be in Grade 1 to Grade 5. The damage classifications shown in Table 4. The probable damage can be estimated based on the RVS score and is given below.

However, it should be realized that the actual damage will depend on a number of factors that are not included in the RVS procedure. As a result, the Table 4. These results can also be used to determine the necessity of retrofitting buildings where more comprehensive vulnerability assessment may not be feasible Sinha and Goyal Table 4. Grunthal Grade 1: Negligible to slight damage No structural damage, slight non- structural damage Hair-line cracks in very few walls.

Fall of small pieces of plaster only. Fall of loose stones from upper parts of buildings in very few cases. Grade 2: Moderate damage Slight structural damage, moderate non- structural damage Cracks in many walls. Fall of fairly large pieces of plaster. Partial collapse of chimneys and mumptys. Grade 3: Substantial to heavy damage moderate structural damage, heavy non- structural damage Large and extensive cracks in most walls. Roof tiles detach. Chimneys fracture at the roof line; failure of individual non-structural elements partitions, gable walls etc.

Grade 4: Very heavy damage heavy structural damage, very heavy non- structural damage Serious failure of walls gaps in walls ; partial structural failure of roofs and floors. Grade 5: Destruction very heavy structural damage Total or near total collapse of the building. The buildings are modeled in SAP V. For any given earthquake load, each of the buildings will undergo certain deformation.

Buildings in reality during earthquake experience several types of damages, but in this study the damage is idealized as the maximum top displacement of the buildings. This is because of the fact that the structures are all designed for ductility under seismic loads and so deformations are more meaningful than forces Tremayne and Trevor The macro-element model is a macroscopic representation of a continuous model Gambarotta and Lagomarsino in which the parameters are directly correlated to the mechanical properties of the masonry elements.

The macro-element parameters should be considered as representative of an average behavior of the masonry panel. The 3-dimensional models are created by joining the masonry walls together. Since macro-elements only consider in-plane behavior, the horizontal floor elements distribute the horizontal actions to the walls, depending on their flexural behavior.

The timber floor elements are modeled as two way equivalent timber shell element. Equivalent timber floor is obtained as floor depth of 0. Masonry wall is modeled as bi-dimensional thin shell element of thickness 0. Building Modeled for the analysis are shown in figure 4. Figure 5. Sample brick wallets were created in the lab of IOE, Pulchowk Campus and three tests were undertaken. Table 5. The starting point for understanding the behavior of masonry structures can be a linear elastic analysis under the assumption of masonry as a homogenous material Ilaria The analyses are performed by carrying out by defining modal linear time history load cases , using a three dimensional model of the structure and a set of opportunely selected ground motion time histories.

Since a single record is not sufficient to describe the behavior of the structure, a sufficient number of records is required Bommer, Acevedo and Douglas But due to technical incapability and instrumental setup for accurate earthquake recording and occasional strong ground motion event, it's hard to have actual earthquake record data. Therefore ground motions assumed for use in this research are synthetic earthquake that consists of a simulated ground motion time histories of El Centro north south, Chamauli and Lalitpura developed by Purusottam Karki.

The three accelerograms peak amplitudes are given in Table 5. The three records considered in this study were scaled linearly to the required PGA. Frequency Content of Lalitpura is 2. Modal analysis provides the vibration characteristics natural frequencies and mode shapes of a structure. A modal analysis is also the starting point for other, more detailed, dynamic analysis, such as harmonic response or a transient analysis Sirajuddin, Potty and J Modal analysis uses the overall mass and stiffness of a structure to find the various periods at which it will naturally resonate.

A building's natural frequency does not match the frequency of expected earthquakes in the region in which the building is to be constructed. If a structure's natural frequency matches an earthquake's frequency, the structure may continue to resonate and experience structural damage.

Two types of modal analysis are Eigen vector and Ritz vector analysis Wik Ritz vector analysis seeks to find modes that are excited by a particular loading. Ritz vectors can provide better basis than Eigen vectors when used for time history analysis.

The mode shapes and frequencies obtained provide excellent insight into the behavior of structures Solution of Eigen Value problem yield eigen vectors and eigen values. In Ritz vector analysis reduced eigen value problem is created, whose solution yields eigen values and the eigen vectors. The eigen values provide approximate natural frequencies and the vectors provide approximate natural modes Chopra Wilson If loads or displacements are applied very slowly, the inertia forces can be neglected and static load analysis can be justified, otherwise dynamic analysis of structure is needed.

The basic seismic motions are the three components of free field ground accelerations that are known at the surface where foundations are laid. It is an estimate that accounts for other unknown factors that affect the accuracy of the functions and that has an impact on the determination of the median PGA in the process of deriving the fragility curves.

It is simply the square root sum of the squares combination of individual variability terms which is equivalent to 0. Modal and time history analysis were carried out using this software. These five buildings are of different geometric configurations but all of them have common material properties. Since they represents the different kinds of traditional brick masonry buildings existing in Jhatapol area, their seismic vulnerability will also be different.

In order to quantify the seismic vulnerability of each building type analytical fragility curves have been generated. These fragility curves defines the probability of the buildings sustaining Slight, Moderate, Extensive, and Complete damage during earthquake. Three accelerograms Lalitpura, Chamauli and El Centro were employed in the construction of fragility curve to take into account, multitude earthquake scenarios representing earthquake of different level of intensity and site condition.

These earthquakes were scaled to meet the required PGA. Each buildings are given structural score in accordance with Rapid Visual Screening method so that a comparative study could be carried out between RVS and Fragility Analysis of these buildings. Result of the analyses are presented in this chapter in tabular and graphical forms. Fragility Curves have been generated at three different earthquakes to consider multitude scenario of earthquakes of different amplitude.

Therefore probability of failure of the building is observed at the PGA value of 0. From fig 6. It also reflects another fact that probability of slight damage is always highest and that of complete damage is least. From Figure 6.

Likewise figure 6. Evaluation of building at El Centro and Chamauli showed nearly the same result as that of Lalitpura. Similarly, other figures 6. Probability of failure of buildings at different damage states at different earthquake scenarios are determined from fragility analysis of the buildings.

The results in order to compare are tabulated from Table 6. Table 6. Buildings B47 and C26 have very high probability i. Analyzing these probabilities the buildings are expected to have moderate damage. FEMA permits use of mean time history result rather than maximum values, provided that seven or more records are used. Since only three earthquake records have been used in this study results cannot be averaged.

Building B4-B5, A48 and C25 are vulnerable to moderate damage at all the given three earthquakes, which means most wall surfaces exhibit diagonal cracks, some of the walls exhibit larger diagonal cracks, masonry walls may have visible separation from diaphragms. Evaluation of building at all three earthquake shows the same result.

RVS score of each building systems have been tabulated as shown in Table 6. Fragility analysis shows that C25 is least vulnerable among the five buildings under study but RVS method providing highest score to A48 among the five buildings, characterize it as least vulnerable. Results from Fragility analysis and RVS methods conflicts with each other.

This is because Kathmandu Valley lies in high seismicity zone and RVS procedure does not enable better assessment of structural vulnerability due to influence of a large number of other factors on the building performance when the ground shaking is very intense. Building is vulnerable to moderate damage from analytical method, whereas the building lies in Grade 2 in the line of EMS98 damage grade.

This may be because of symmetric building plan and regular configuration of the building as RVS has ascertained negative score for irregularity in building. This building is found more vulnerable to Lalitpura earthquake than Elcentro and Chamauli. This may be due to the reson that natural frequency of building 3. This made the building vulnerable according to RVS method scoring only 0. However building is vulnerable to moderate damage from fragility analysis. It has plan length breadth ratio of 1.

Result from RVS has shown this building less vulnerable than from analytical method as RVS ignores the significance of its length breadth ratio in its scoring procedure. Hence, the building has been provided with structural score of 0. The results from both method is quite similar for this building. The vulnerability is justifiable by its irregularity in both plan and vertical, large openings It has opening percentage higher than other buildings however this building is least vulnerable than other buildings in this study from analytical method.

This may be due to its number of storey. This is the shortest building among the five buildings in the study. The result is understandable because vulnerability due to earthquake increases with increasing number of storey in buildings. From RVS method this building scores 0.

Field surveys, documentation, experiments as well as laboratory analysis were undertaken as a part of the research project. This thesis is based on the survey data and results of lab tests carried out during research of the project. Five buildings of different configurations representing all types of buildings in the area under study are taken for analysis and modeled in SAP V.

Fragility curves which define the probability of traditional brick masonry buildings sustaining slight, moderate, extensive and complete damage states due to earthquakes have been presented in this thesis report. Three accelerograms Lalitpura, Chamauli and El Centro were employed in the construction of fragility curve to take into account the multitude earthquake scenarios representing earthquake of different levels of intensity and site conditions.

These curves are useful in determining the probabilities of damages and making rational decisions on retrofitting of the existing buildings. Associated with each damage type is repair or replacement cost. If a damage matrix and the corresponding set of repair and replacement costs are available it is possible to estimate the expected repair and replacement costs i.

The major conclusions are outlined as follows: 1. Fragility Curves generated are different for different building system. This is due to their variations in number of storey, percentage of openings, plan irregularities, vertical irregularities, length breadth ratio in plan and modal frequencies. This suggests that these factors are responsible for their variations in seismic vulnerability.

Maximum top displacement of a building at three different earthquake records were different. This variation is due to variation in duration and peak amplitude of various earthquakes. Building A48, B4-B5 and C25 are vulnerable to moderate damage at all given three earthquakes. The sample was used to carry a deterministic seismic vulnerability assessment, applicable to all superstructure-substructure combinations.

Analysis considerations, such as the calculation of critical capacity measures like moment-curvature and a pushover analysis, are leveraged to accurately account for non-linear effects like force redistribution. This effect is a result of non-simultaneous structural softening in multi-span bridges that maintain piers of varying heights and stiffnesses. The results of this deterministic seismic assessment procedure are also leveraged to identify trends in the structural response of the sample set.

These trends are used to identify limit state thresholds for the development of fragility functions. This conditional probabilistic representation of bridge damage is coupled with the probability of earthquake occurrence to predict the performance of the structure for a given return period. This probabilistic approach alongside a Monte Carlo simulation is applied to assess the vulnerability of linked bridges along key-access corridors throughout the state.

With this robust seismic vulnerability methodology, DOTs will have the capability of identifying vulnerable corridors throughout the state allowing for the proactive prioritization of retrofits resulting in the improved seismic performance and resiliency of their transportation network. Degree Type Master of Science. Shirley Dyke. Julio Ramirez.

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