Seismic Response of Large span slab in Horizontal Setback Building

The demand for multi-storey buildings is increasing day by day. Residential plus commercial building is mainly used for wide span needs. Wide span required for Flat slab, Waffle slab and ribbed slab stands An excellent option for architects when larger openings in a building need to be covered with as few columns as possible. The use of different types of plates is developing as a new trend and is becoming a major challenge for structural engineers. Therefore, it is necessary to study about its structural behavior. The project is carried out under earthquake zone III under the earthquake analysis of G+9 storey building. For this study, four different types of large span slab structure are modelled in C-shape (Horizontal Setback Building) having 10-stories i.e. G+9 storied buildings with 3.50 meters height for each story is modelled and analysed. The plan area of all four buildings is same i.e. 2859 square meters (49.50 m x 82.50 m) each. These buildings were designed in compliance with the Indian Code of Practices for earthquake resistant design of buildings. Base of the building were fixed. The square sections are used for structural elements. The height of the buildings is considered constant throughout the structure. The buildings are modelled using ETABSvr.2016. Keywords: large span slab, ETABSvr.2016, Horizontal Setback Building, Flat slab, Waffle slab and ribbed slab

CHARACTERIZATION OF ENERGY DISSIPATIVE CUSHIONS MADE OF Ni-Ti SHAPE MEMORY ALLOY

Earthquake-resistant design of structures requires dissipating seismic energy by deformations of structural members or additional fuse elements. Owing to its easy-to-produce, plug-and-play, high equivalent damping ratio, and large displacement capacity characteristics, energy dissipative steel cushions were found to be an efficient candidate for this purpose. However, similar to other conventional metallic dampers, residual displacement after a strong shaking is the most notable drawback of the steel cushions. In this work, cushions produced from Ni-Ti shape memory alloy are evaluated numerically by experimentally verified finite element models to assess their impact on the performance of earthquake-resistant structures. Furthermore, a reinforced concrete testing frame is retrofitted with energy dissipative steel and Ni-Ti cushions. Performance of the frames (e.g. dissipated energy by the cushions, hysteretic energy to input energy ratio, maximum drift, and residual drift) with different types of cushions are evaluated by nonlinear response history analyses. The numerical results showed that the steel cushions are effective to reduce peak responses, while Ni-Ti cushions are more favorable to reduce residual drifts and deformations. Hence, a hybrid system, employing the steel and shape memory alloy cushions together, is proposed to reach optimal seismic performance.

Proposal of orientation-independent measure of intensity for earthquake-resistant design

A new measure of ground motion intensity in the horizontal direction is proposed. Similarly to other recently proposed measures of intensity, the proposed intensity measure is also independent of the as-installed orientation of horizontal sensors at recording stations. This new measure of horizontal intensity, referred to as MaxRotD50, is defined using the maximum 5%-damped response spectral ordinate of two orthogonal horizontal directions and then computing the 50th percentile for all non-redundant rotation angles, that is, the median of the set of spectral ordinates in a range of 90°. This proposed measure of intensity is always between the median and maximum spectral ordinate for all non-redundant orientations, commonly referred to as RotD50 and RotD100, respectively. A set of 5065 ground motion records is used to show that MaxRotD50 is, on average, approximately 13%–16% higher than Rot50 and 6% lower than RotD100. The new measure of intensity is particularly well suited for earthquake-resistant design where a major concern for structural engineers is the probability that the design ground motion intensity is exceeded in at least one of the two principal horizontal components of the structure, which for most structures are orthogonal to each other. Currently, design codes in the United States are based on RotD100, and hence using MaxRotD50 for structures with two orthogonal principal horizontal components would result in a reduction of the ground motion intensities used for design purposes.

Performance Based Seismic Design of Reinforced Concrete Building by Non-Linear Static Analysis

In past two decades earthquake disasters in the world have shown that significant damage occurred even when the buildings were designed as per the conventional earthquake-resistant design philosophy (force-based approach) exposing the inability of the codes to ensure minimum performance of the structures under design earthquake. The performance based seismic design (PBSD), evaluates how the buildings are likely to perform under a design earthquake. As compared to force-based approach, PBSD provides a methodology for assessing the seismic performance of a building, ensuring life safety and minimum economic losses. The non-linear static procedures also known as time history analysis are used to analyze the performance of structure . Plastic hinge formation patterns, plastic rotation, drift ratio and other parameters are selected as performance criterias to define different performance level. In this paper, a five-storey RC building is modelled and designed as per IS 456:2000 and analyzed for lmmediate occupancy performance level in ETABS2015 softwere. Analysis is carried out as per FEMA P58 PART 1 & 2. Plastic hinges as per FEMA273. From the analysis, it is checked that the performance level of the building is as per the assumption

Design and Analysis of Earthquake Resistant Building (Three Storeyed R.C.C. School Building) using STAAD.PRO

The field of Earthquake Engineering has existed in our country for over 35 years now. Indian earthquake engineers have made significant contributions to the seismic safety of several important structures in the country. However, as the recent earthquakes have shown, the performance of normal structures during past Indian earthquakes has been less satisfactory. This is mainly due to the lack of awareness amongst most practising engineers of the special provisions that need to be followed in earthquake resistant design and thereafter in construction. In India, the multi-storied building is constructed due to high cost and scarcity of land. In order to utilize maximum land area, builders and architects generally proposed asymmetrical plan configuration. These asymmetrical plan buildings, which are constructed in seismic prone areas, are likely to be damaged during earthquake. Earthquake is a natural phenomenon which can be generate the most destructive forces on structure. Buildings should be made Safe for lives by proper design and detailing of structural member in order to have a ductile form of failure. The concept of earthquake resistant design is that the building should be designed to resist the forces, which arises due to Design Basic Earthquake, with only minor damages and the forces which arises due to Maximum Considered Earthquake, with some accepted structural damages but no collapse. This paper studies the Earthquake Resisting Building.

Probabilistic seismic hazard analysis for Northern Tanzania Divergence Region and the adjoining areas

This paper presents the seismic hazard levels for the Northern Tanzania Divergence (NTD) and adjoining areas by using area seismic source zones. The 15 source zones were considered based on the major geological and tectonic features, faulting style, and seismicity trends. For each source, earthquake recurrence parameters were computed by using the earthquake catalogue with events compiled from 1956 to 2011. The peak ground accelerations (PGA) and spectral accelerations (SA) at 0.2 and 2.0 second, respectively, were computed for a 10% probability of exceedance in 50 years at sites defined by a 0.1° x 0.1° grid. The recurrence parameters of 15 zones and attenuation relations developed by Akkar et al. (2014) and Chiou and Youngs (2014) were integrated in a logic tree. Obtained results that are presented as hazard maps show strong spatial variations ranging from 60 to 330 cm/s/s for PGA, from 100 to 650 cm/s/s at 0.2 sec and from 6 to 27 cm/s/s at 2 sec for 475 years mean return period and 5% damping. Hazard levels depict the general tectonic setting of the study area with the western (Eyasi-Wembere) and central (Natron-Manyara-Balangida) rift segments having relatively high PGA values compared with the eastern Pangani rift. This work provides indications of seismic hazards to policymakers and planners during planning and guidelines for earthquake-resistant design engineers. Keywords: Homogeneous Earthquakes Catalogue; GMPE; PSHA; NTD