Abstract

The overall capacity of a structure depends on the strength and deformation capacity of the individual components of the structure. This paper deals with the prediction of effect of a member on global performance of the structure. The performance of a 5 storey RC frame, designed for Indian standard codes has been presented. Non linear pushover analysis is used to draw the capacity curve. During the pushover analysis when the structure becomes unstable, the failed members are identified. In the present study, end columns of the bottom storey which exists in failed members are strengthened by increasing the longitudinal reinforcement, increasing the c/s area and reducing the shear reinforcement spacing. Increase of longitudinal reinforcement or decrease of shear reinforcement spacing not effected much the strength capacity, but the ductility is increased in both the cases. Increasing the c/s area of two columns increased the strength and stiffness of the frame, but the ductility is increased up to a certain limit and then decreased. Parametric study also done for individual column performance with same geometric and material properties as it exists in the frame. The performance of individual column is completely different with frame performance though the geometric and material properties are same this is because of the frame action where redistribution of forces takes place when the member fails in the frame.

Abstract

The earthquake resistant design of structures according to the existing design philosophy aims to ensure that during their lifetime, the structures resist the maximum possible earthquake without collapse. This philosophy ignores the fact that for the allowable damage at the end of the design life, it is necessary to account for the seismicity of the area in a comprehensive manner i.e., in terms of magnitudes with proper spatial distributions around the site. It is also necessary to estimate damage due to each of these events and also cumulative damage till date. Such a procedure is proposed in the paper and it is applied to heritage structures which stand for longer duration compared to ordinary buildings. As a case study, the proposed methodology is used to evaluate damage to Golkonda Fort located in Zone II according to IS 1893-2002. Proposed approach is based on the estimation of Power spectral density function (PSDF) of earthquakes already occurred and then estimation of damage to the structure during each of these events. Golkonda Fort is modeled using Applied Element Method (AEM). Pushover analysis of the AEM model is also carried out. The damage computed from the proposed approach is plotted on the fragility curve obtained from the push over analysis for comparison.

Abstract

In recent years, the introduction of Pre Engineered Building (PEB) concept in the design of structures has helped in optimizing design. The adoptability of PEB in the p lace of Conventional Steel Building (CSB) design concept re sulted in many advantages, including economy and easier fabricatio n. In this study, an industrial structure (Ware House) is analyzed an d designed according to the Indian standards, IS 800&1984, IS 800&2007 and also by referring MBMA&96 and AISC&89. In this study, a structure with length 187m,width 40m,with clear height 8m and havi ng R&Slope 1:10,isconsidered to carry out analysis& design for 2D frames (End frame, frame without crane and frame with 3 module cranes). The economy of the structure is discussed in terms of i ts weight comparison, between Indian codes (IS800&1984, IS800 &2007) & American code (MBMA&96), & between Indian codes (IS 800&1984, IS800&2007).

Abstract

The pipeline systems are commonly used to transport water, sewage, oil, natural gas and other materials world over. These pipelines run over long distances and in some instances they cross high seismic areas including fault crossings. Many buried pipelines in India run through high seismic areas and are exposed to considerable seismic risk. These pipelines should be designed in such a way that they remain functional even when they are subjected to high intensity earthquake shaking. This paper illustrates the performance of one of the high pressure gas pipeline in the state of Gujarat, under the fault movement. Analysis shows that the burial depth of pipeline should be minimized in the fault zones in order to reduce soil restrain on the pipeline during fault movement.

Abstract

Pipeline generally extends over long distances traversing through wide variety of different soils, geological conditions and regions with different seismicity and ground motions. Vulnerability of the pipeline due to seismic hazards can be divided in to three categories i.e. hazard due to ground vibration, hazard due to faulting and hazard due to permanent ground deformation (PGD). Though there are no severe damage were observed due ground vibration in the modern buried pipeline though it may trigger to secondary effect of landsliding and ground motion due to liquefaction. Main stream researches in past especially analytical models are limited to strike slip fault motions with tension in pipe case only. As the large geometric changes incorporating in analytical study is a tricky task; however pipeline subjected to the large ground motion itself is a phenomenon of large geometric changes. Especially when pipeline subjected to compression, where in addition to material deformation it also undergoes general as well as local buckling with bending, contradictorily past work mostly assumed that pipeline is under tension. With day by day increasing capacity of computation and advancement in numerical modelling, one can find more facts for pipeline subjected to large motions including cases of pipe under compression as well. In this paper, past work is reviewed for pipeline subjected to large ground motion. A three dimensional FE based numerical model is suggested to carry out pipeline performance of buried pipeline subjected to large motion. A proposed model includes material nonlinearity, as well as considers the large geometric deformation. For this purpose, three dimensional FE program is developed using MATLAB. Displacement controlled Arc-length technique is implemented to solve the nonlinear behavior. To reduce the computation time of analysis here parallelization tool kit of MATLAB is utilized. Keywords: Buried continuous pipeline; Large ground motion; Nonlinear-large deformation FEM; Displacement controlled Arc-length technique.

Abstract

Past response analyses of structures under earthquake excitations revealed that both the maximum displacement and the number of inelastic excursions cause higher damage to the structure. However, it is observed that the quantification of damage is a difficult task. In the paper, a new methodology is proposed for the quantification of damage of reinforced concrete framed structure. This method is based on the nonlinear energy dissipated by the structure along the complete displacement path. Three methods have been proposed to assess the global damage state of the structure, for any deformation level. In these proposed methods, the damage index is expressed as the ratio of nonlinear dissipated energy at an instant, to the total non-linear energy capacity of the structure. To calculate the energy, pushover curve is plotted between base shear versus displacement at C.G of external force profile, which provides consistent meaning for work done by external forces. The area under the curve represents the energy dissipated by the structure. To illustrate the proposed concept, two cases i.e., G+5 and G+9 story structures have been considered. Keywords: Pushover analysis, expended energy, total energy, damage index.

Abstract

According to current seismic zone map around 60% of India’s land area is prone to moderate to severe earthquakes. And earthquake losses, in terms of life and property in last 2 decades have been high, with housing contributing to over 95% of life loss; this failure attributed to improper design and construction practices of housing.Thus, all the three factors influencing earthquake risk of houses in India are above danger levels in many districts of India – hazard, exposure and vulnerability. This paper classifies housing risk in the entire country into four groups; about 47% of population is living in the highest risk. Gigantic effort is required to mitigate the risk. The paper also suggests some steps to move forward to reduce earthquake risk to housing in India.

Abstract

Buildings in urban areas and metropolitan cities are constructed very close to each other. This is because of the requirement of functional usage and high land value. Because of the insufficient gap between the adjacent buildings or adjacent units of the same buildings, they are most vulnerable for seismic damage like pounding. The adjacent land generally belongs to different land owners, where they construct the buildings for different requirements (residential, public). This leads to different dynamic properties of the adjacent buildings. During the earthquakes these may vibrate in or out-of-phase leading to damages, varying from slight architectural damages to severe structural damages. In this paper the pounding analysis is done for different cases of different building positions like buildings of same height and same floor level to buildings in row, are analyzed using SAP (2000) software package. When the two buildings are placed at different floor levels the impact force is more than buildings with the same floor levels. Also when buildings are in a row exterior building suffers more pounding damage than the interior building.

Abstract

For many, Accessibility is about disability and aiding the disabled user. We argue for a much broader definition: One that is inclusive of not only the disabled and the technologically deprived, but also the able-bodied, who may still be facing linguistic, socio-cultural, cognitive type barriers. Further, we discuss how to overcome this new broad set of barriers (which have elsewhere been called New Accessibility). Modification of original static content to new target content – a technique of Renarration – is modeled as a webpage transformation. This is operationally realized as "Sweets". Sweets are external meta data used for transformation of the web page. They are collaboratively and socially produced either by humans or human triggered Sweet based web applications. The entire web architecture featuring Sweets, their repositories and their web applications is explained and shared as a potential mechanism for overcoming New Accessibility barriers. Two web applications, Alipi and Mural Annotation for IDH, are finally showcased to highlight that Sweets based architecture does indeed help in facing the barriers of New Accessibility.

Abstract

Cross origin interactions constitute the core of today’s collaborative Word Wide Web. They are, however, also the cause of malicious behaviour like Cross-Site Request Forgery (CSRF), clickjacking, and cross-site timing attacks, which we collectively refer as Web Infiltration attacks. These attacks are a rampant source of information stealth and privacy intrusion on the web. Existing browser security policies like Same Origin Policy, either ignore this class of attacks or, like Content Security Policy, insufficiently deal with them. In this paper, we propose a new declarative browser security policy — “Cross Origin Request Policy” (CORP) — to mitigate such attacks. CORP enables a server to have fine-grained control on the way different sites can access resources on the server. The server declares the policy using HTTP response headers. The web browser monitors cross origin HTTP requests targeting the server and blocks those which do not comply with CORP. Based on lessons drawn from examining various types of cross origin attacks, we formulate CORP and demonstrate its effectiveness and ease of deployment. We formally verify the design of CORP by modelling it in the Alloy model checker. We also implement CORP as a browser extension for the Chrome web browser and evaluate it against real-world cross origin attacks on open source web applications. Our initial investigation reveals that most of the popular websites already segregate their resources in a way which makes deployment of CORP easier.