Abstract

Indian standard code of practice for plain and reinforced concrete IS 456 was last revised in 2000 after 22 years of the third revision. The major revision done in the new code is shift in design philosophy from working stress method to limit state method. The new code has not shown any significant changes in the concepts of structural design, material properties for high strength of concrete and steel, material grade limitation for seismic design, design of deep beam and walls, design of infilled frames, design of beam column joint and provisions for effective length of frame members. The code does not clearly mention about mode of failures such as shear, flexure in structural members. In the present paper a comprehensive literature review on the design strength of materials, stress stain curve for concrete, steel and confined concrete, partial safety factors and limitations/recommendations for usage of concrete grade and reinforcement steel grade in design provisions of Indian Standards, American Standards, European Standards, New Zealand Standards, Japanese Standards and from the latest available literature is done.

Abstract

Strong ground motions are the most desirable for the earthquake-resistant design of structures. If the site at which a major construction is required has less ground motion records, then artificial ground motions will serve the purpose. In highly seismic areas like Kashmir and the Himalaya region, artificial ground motions are quite helpful. Artificial accelerograms can be generated either through analytical or numerical procedures. Several methods were suggested in the literature for generating artificial ground motions. However, suitability of method for the region is to be understood before application. The main objective of this paper is to generate synthetic accelerograms of May 01, 2013, Doda earthquake using modified semi-empirical approach. A MATLAB code is written to generate the ground motion records of 1991 Uttarkashi earthquake and also validate the results. Based on effectiveness of the code …

Abstract

Structures are being built very close to each other in metropolitan areas where the cost of land is very high. Due to the proximity of the structures, they often collide with each other when subjected to earthquakes. To mitigate the amount of damage from pounding, the most simplest and effective way is to provide minimum separation distance. Generally most of the existing buildings in seismically moderate regions are built without codal provisions. The main objective of the present study is to check the adequacy of provisions given in codes of various countries. For this purpose, four pairs of structures were selected. The gap between structures was estimated according to codes of different countries and the same were subjected to earthquake excitation. Some codal provisions failed to satisfy the safety requirements, whereas some were safe. Based on this study, recommendations were drawn.

Abstract

Huge damages and loss of lives due to failure of glass panels and façade structures in buildings reported during past disasters such as the 1983 Mid-Japan Sea Earthquake and glass curtain façade failures due to 1994 Typhoon in Wan Chai district of Hong Kong suggest that there is a significant difference between available research literature related to structural mechanics, codes available on glass failure behavior and that with the safe structural design, mitigation practices actually implemented by modern construction firms and industries using significant structural glass components in buildings especially in newly emerging cities of India. This study presents a web application that simulates the behavior of glass plates towards two independent loading events: wind pressure acting transversely on the plates and seismic excitations deforming the in-plane glass frames leading to stress concentration patterns around plates. The App starts by prompting the user to input site-specific, plate geometry, building type and class, terrain, location-specific parameters. The framework of the application is designed in three stages. Stage-I uses computational GPS algorithms to determine Basic wind speed of the location based on wind zone map of India, combines analytical procedures in IS 875 Part III and Indian draft codes to formulate SNT (Standard Nominal Thickness) of glass plates and net design wind pressure acting transversely on them. In stage II, Deflection and bending behavior are investigated and relevant computations are performed. Mesh-generation procedures and Finite Element Method are implemented and coded by authors to solve the …

Abstract

In the present scenario of building construction world-wide, there is a significant increase in the cost percentage of non-structural elements compared to overall building cost. However, in some cases during past earthquakes, where the main structure suffered minimal damage, it was noticed that there were severe problems in the functionality of building and also sometimes leading to injuries & life loss. It is observed that significant percentage of population is injured due to overturning of objects such as furniture. This problem is attributed mainly to the behavior of non-structural elements which are not designed taking into account their seismic performance. The aim of this study is to analyze the behavior of a rigid body ie a NSE, particularly the toppling behavior under the action of seismic forces. A linearized solution for the dynamic equation of motion of the rigid body is obtained. The results are obtained in the form of angle of rotation of body against time, providing limits of safety of the NSE against toppling under applied seismic loading. A transformer has been modelled to illustrate the same. Also a tool has been generated using python scripts to graphically simulate the behavior of nonstructural elements under earthquake loading, by placing NSEs in different floors. This tool helps us in identifying whether the NSE will slide, rock or topple when subjected to certain seismic loading and provides the limits of safety for the same.

Abstract

We consider a generalization of the Standard Model whose action displays conformal invariance in d dimensions. The model contains a strongly coupled dark matter sector which breaks conformal symmetry dynamically. The model evades conformal anomaly and leads to identically zero vacuum energy in flat space-time. Hence it does not suffer from the problem of fine tuning of the cosmological constant. We determine the contribution of non-relativistic matter to the energy-momentum tensor and determine a parameter regime in which it approximately reduces to the standard result. We show how dark energy and dark matter arises in this model. We discuss the parameter range for which the model reduces to the ΛCDM model and hence is consistent with observations.

Abstract

We present the scalar leptoquark pair production process at the LHC computed at the next-to-leading order in QCD, matched to the Pythia parton shower using the MC@ NLO formalism. We consider the leading order decay of a leptoquark to a lepton (e, μ, τ or ν e, ν μ, ν τ) and a jet and observe the effects of parton shower on the final states. For demonstration, we display the kinametical distributions of a selection of observables along with their scale uncertainties for the 13 TeV LHC. We also present pair production cross sections and K-factors using a massless five-quark flavor scheme for different LHC center-of-mass energies. The complete stand-alone code is available online.

Abstract

Quark-lepton compositeness is a well-known beyond the Standard Model (SM) scenario with heavy exotic particles like leptoquarks (LQs) and leptogluons (LGs) etc. These particles can couple to leptons and jets simultaneously. In this letter, we use the recent CMS scalar LQ search data in the e e j j and eej channels to probe this scenario. We recast the data in terms of a color octet partner of the SM electron (or a first generation spin-1/2 LG) that couples to an electron and a gluon via a dimension five operator suppressed by the quark–lepton compositeness scale (Λ). By combining different production processes of the color octet electron (e 8) at the LHC, we use the CMS 8 TeV data to obtain a simultaneous bound on Λ and the mass of the e 8 (M e 8). We also study the reach of the 13 TeV LHC to discover the e 8 and interpret the required luminosity in terms of M e 8 and Λ.

Abstract

Several remote user authentication techniques for telecare medicine information system (TMIS) have been proposed in the literature. But most existing techniques have limitations such as vulnerable to various attacks, lack of functionalities, and inefficiency. Recently, Amin and Biswas proposed a three‐factor authentication and key agreement technique for TMIS. But their scheme is inefficient and has several security drawbacks. The attacks such as privileged‐insider, user impersonation, and strong reply attacks are possible on their scheme. It also has flaw in password update phase. In order to overcome drawbacks of their scheme, a new provably secure and efficient three‐factor remote user authentication scheme for TMIS is proposed in this paper. The proposed scheme overcomes all drawbacks of their scheme and also provides additional features such as user unlinkability, user anonymity, efficient password, and biometric update. The rigorous informal and formal security analysis using random oracle models and the mostly acceptable Automated Validation of Internet Security Protocols and Applications tool is also performed. During the experimentation, it has been observed that the proposed scheme is secure against various known attacks that include replay and man‐in‐the‐middle attacks. Furthermore, the analysis of computation and communication cost estimation of the proposed scheme depicts that our scheme is efficient as compared with other related exiting schemes.

Abstract

In 2012, Mun et al. proposed an enhanced secure authentication with key-agreement protocol for roaming service in global mobility networks environment based on elliptic curve cryptography. They claimed that their protocol is efficient and resistant to prominent security attacks. The careful analysis of this study proves that Mun et al.'s protocol is susceptible to several attacks such as replay attack, man-in-middle attack, user impersonation attack, privileged insider attack, denial-ofservice attack, no login phase and imperfect mutual authentication phase. In addition, this study proposes an enhanced lightweight authentication with key-agreement protocol for mobile networks based on elliptic curve cryptography using smart cards. The proposed protocol is lightweight and perfectly suitable for real-time applications as it accomplishes simple one-way hash function, message authentication code and exclusive-OR operation. Furthermore, it achieves all the eminent security properties and is resistant to various possible attacks. The security analysis and comparison section demonstrates that the proposed protocol is robust compared with Mun et al.'s protocol.