Abstract

Many countries have their own building codes-of-practice for earthquake resistant design of structures. These codes provide conventional approach to earthquake resistant design of buildings with sufficient strength, stiffness and inelastic deformation capacity to withstand a given level of earthquake generated force. Under a given earthquake, the level of damage to a structure is greatly influenced by nonlinear capacity of its members. Even when the nonlinear capacities are same, the overall damage is critically influenced by the structure’s shape, size and geometry.This paper presents the research on the influence of aspect ratio on overall damage of the structure subjected to earthquake loading. In this paper a numerical study is carried out for 3 benchmark structures, with an aspect ratio (height to widthratio) of 3, 1 and 0.3, to define failure pattern in nonlinear state. Nonlinear static pushover analysis is performed to understand the capacity of structure and expended energy based damage assessment is used to estimate the damage. The results are compared in terms of damage, displacement and plastic hinge pattern

Abstract

n present scenario buildings with floating columns are of typical feature in the modern multistorey construction practices in urban India. Such types of constructions are highly undesirable in building built in seismically active areas. This paper studies the analysis of a G+5 storey normal building and a G+5 storey floating column building for external lateral forces. The analysis is done by the use of SAP 2000. This paper also studies the variation of the both structures by applying the intensities of the past earthquakes i.e., applying the ground motions to the both structures, from that displacement time history values are compared. This study is to find whether the structure is safe or unsafe with floating column when built in seismically active areas and also to find floating column building is economical or uneconomical.

Abstract

Capture the mechanical behaviour of RC frame systems subjected to Lateral loading and estimating the damage state of structure are still changing tasks in civil engineering

Abstract

Nuclear power plant is one of the largest source of producing electricity in India after thermal, hydroelectric and renewable sources of electricity. As of 2013, India has 21 nuclear reactors in operation in 6 nuclear power plants, having an installed capacity of 5780 MW and producing a total of 30, 293 GWh of electricity while six other reactors are under construction and are expected to generate an additional 6,100 MW. After 2011 Fukushima earthquake in Japan, safety of nuclear reactors has become a major concern. For assessing safety it is utmost important to have information on expected earthquake events. In case of lack of sufficient information, artificial ground motions may be generated by using geological features and faults information. This study presents simulation of near field generated ground motions of Rawatbhata nuclear power plant. For this purpose, three faults nearer to the power plant have been selected to the generate ground motions using semi-empirical approach. It is observed that as the source (M) of the earthquake increases, the amplitude of the ground motion, duration and energy content increases. Similarly, the spectral accelerations also increase due to all three active faults.

Abstract

Earthquake performance of Reinforced concrete bare frame has been well documented in the past. Also, damage patterns in reinforced concrete frames during the past earthquakes have been extensively studied. However, more recently, several destructive earthquakes, including the 1999 Athens (Greece) earthquake, the 1999 Ýzmit and Düzce earthquakes (Turkey), 1999 Chi Chi (Taiwan) earthquake, 2001 Bhuj (India) earthquake, and the 2003 Boumerdes (Algeria) earthquake, have given more insights to performance of RC frame constructions. In order to understand the complete behavior of RC frame, it is required to study the performance from no loading condition till the complete collapse. In this paper, a set of four bare frames designed as per Indian Standards are considered. All the frames are subjected to Northridge earthquake ground motion. Newly developed numerical model called Applied Element Method (AEM) is considered for analysis. Initially, the linear analysis is carried out and the results were compared with commercially available software. Later, progressive collapse analysis is performed. Collapse process of each bare frame is discussed in detail.

Abstract

Different shapes of column cross sections are possible for design of structures which ultimately affect the overall performance. Various cross section reinforced concrete columns like square, circular, plus, L, and T shaped with same cross sectional area and reinforcement are modelled. In order to make this study more practically applicable, three models each of multi storeyed structures of different number of storeys were analysed for non-linear static responses. One of the models used conventional rectangular columns, second used circular columns throughout and another model employed combination of various geometrically possible column cross sections such as L, T and plus (+) shaped columns. The study compares response modification factors for above mentioned structures.

Abstract

Several biometric-based remote user authentication schemes using smart cards have been proposed in the literature in order to improve the security weaknesses in user authentication system. In 2012, An proposed an enhanced biometric-based remote user authentication scheme using smart cards. It was claimed that the proposed scheme is secure against the user impersonation attack, the server masquerading attack, the password guessing attack, and the insider attack and provides mutual authentication between the user and the server. In this paper, we first analyze the security of An’s scheme and we show that this scheme has three serious security flaws in the design of the scheme: (i) flaw in user’s biometric verification during the login phase, (ii) flaw in user’s password verification during the login and authentication phases, and (iii) flaw in user’s password change locally at any time by the user. Due to these security flaws, An’s scheme cannot support mutual authentication between the user and the server. Further, we show that An’s scheme cannot prevent insider attack. In order to remedy the security weaknesses found in An’s scheme, we propose a new robust and secure anonymous biometric-based remote user authentication scheme using smart cards. Through the informal and formal security analysis, we show that our scheme is secure against all possible known attacks including the attacks found in An’s scheme. The simulation results of our scheme using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool ensure that our scheme is secure against passive and active attacks. In addition, our scheme is also comparable in terms of the communication and computational overheads with An’s scheme and other related existing schemes. As a result, our scheme is more appropriate for practical applications compared to other approaches.

Abstract

The authentication protocols are trusted components in a communication system in order to protect sensitive information against a malicious adversary in the client-server environment by means of providing a variety of services including users' privacy and authentication. In the cryptographic protocols, understanding the security failures is the key for both patching to the existing protocols and designing the future protocols. Recently, in 2014, Wang proposed an improved Elliptic Curve Cryptography (ECC) based anonymous remote authentication scheme using smart card and claimed that the proposed scheme is secure against password guessing attack, smart card lost/stolen verifier attack, and also preserves user anonymity and prevents credential leakage. However, in this paper, we show that Wang's scheme fails to preserve the user anonymity and does not prevent the off-line password guessing attack, credential leakage and smart card lost/stolen verifier attack. In order to withstand those security pitfalls found in Wang's scheme, we aim to propose a new secure privacy-preserving ECC-based client authentication with key agreement protocol using smart card. Through the formal and informal security analysis we show that our scheme is secure against possible known attacks including the off-line password guessing attack, credential leakage attack and smart card lost/stolen verifier attack. Our scheme also preserves the user anonymity property. In addition, we simulate our scheme for the formal security verification using the widely-accepted AVISPA (Automated Validation of Internet Security Protocols and Applications) tool and show that our scheme is secure against passive and active attacks. Our scheme provides high security along with low computational and communication costs. As a result, our scheme is practically suitable for mobile devices in the client-server environment as compared to other related schemes in the literature.

Abstract

In real-life applications, ensuring secure transmission of data over public network channels to prevent malicious eavesdropping of the data is an important issue in distributed network environment. There are several potential security risks in protecting data and providing access control over the data. It is a challenging problem to manage dynamically the access rights to the resources and protect them from unauthorized access.Several migration access control mechanisms have been proposed in the literature using hierarchical structure to manage the cryptographic keys to prevent from unauthorized access of resources. However, most of them suffer from some known attacks and they do not efficiently support all required dynamic properties for mobile agent environment. Since, in practical scenarios, from time to time changing of decryption key of a confidential file provides maximum security for the system, it affects significantly the performance of the key management mechanism. In this paper, we propose a novel dynamic migration access control mechanism for the mobile agents (DMAMA) in a distributed network environment using symmetric-key cryptosystem. Further, we provide an elliptic curve cryptography based signature (El-Gamal type) on the decryption key assigned to the confidential file to avoid unauthorized modifications by an attacker. Moreover, DMAMA provides an efficient solution to the dynamic property such as changing decryption key of a confidential file, whereas other schemes do not provide. In addition, DMAMA is efficient in computation and storage overheads as compared to the other related existing schemes. Through the informal and formal security analysis, we show that DMAMA is secure against possible known attacks including man-in-the-middle attack as well as DMAMA provides backward secrecy to the decryption key of a confidential file when adding a new node or creating a new relationship in the existing hierarchy. As a result, higher security, low computational and storage overheads along with efficient access control properties make DMAMA more suitable for practical applications compared to the other related schemes.

Abstract

Recently, in 2013, Wu et al. proposed an efficient adaptable and scalable group access control scheme (GAC) for managing wireless sensor networks and they claimed that their proposed GAC approach provides the forward secrecy and backward secrecy, and it also prevents the man-in-the-middle attack. However, in this paper, we revisit Wu et al.’s scheme and show that Wu et al.’s scheme fails to provide the forward and backward secrecy to the group access key (GAK), and also their scheme does not prevent the man-inthe-middle attack and it does not provide the mutual authentication between a node and the task manager. Moreover, in Wu et al.’s scheme, all the past GAKs used by a node can be revealed to an adversary when that node is compromised. We then aim to propose a novel group access control mechanism to withstand the security weaknesses found in Wu et al.’s scheme while retaining the original merits of their scheme. Through the rigorous informal security analysis and the formal security analysis using the widely-accepted Burrows–Abadi–Needham logic, we show that our scheme is secure against various known attacks including the attacks found in Wu et al.’s scheme. Moreover, in our scheme, the vulnerability of the GAKs used by a node is limited and bounded to the last GAK update protocol interval when that node is compromised by an adversary. Our scheme provides efficient dynamic properties such as joining and leaving of a node from a group along with high security and the required desirable features as compared to Wu et al.’s scheme, and as a result, our scheme is very suitable for the practical applications.