Earth's fractured geology is visible in its fault lines. It is along these lines that earthquakes occur, sometimes with disastrous effects. These disturbances can significantly influence urban ...development, as seen in the aftermath of two earthquakes in Messina, Italy, in 1908 and in the Belice Valley, Sicily, in 1968. Following the history of these places before and after their destruction, this book explores plans and developments that preceded the disasters and the urbanism that emerged from the ruins. These stories explore fault lines between "rural" and "urban," "backwardness" and "development," and "before" and "after," shedding light on the role of environmental forces in the history of human habitats.
In most current building codes, seismic design of non-structural components (NSCs) is addressed through empirical equations that do not capture NSC response amplification due to tuning effects with ...higher and torsional modes of buildings and that neglect NSC damping. This work addresses these shortcomings and proposes a practical approach to generate acceleration NSC floor design spectra (FDS) in buildings directly from their corresponding uniform hazard spectra (UHS). The study is based on the linear seismic analysis of 27 reinforced concrete buildings located in Montreal, Canada, for which ambient vibration measurements (AVM) are used to determine their in situ three-dimensional dynamic characteristics. Pseudo acceleration floor response spectra (PA-FRS) are derived at every building floor for four different NSCs damping ratios. The calculated roof FRS are compared with the 5% damped UHS and a formulation is proposed to generate roof FDS for NSCs with 5% damping directly from the UHS.
This paper extends the methodology presented in the companion paper to study the effects of non-structural components' (NSCs) damping ratio and their location in the building on the ...pseudo-acceleration floor response spectra (PA-FRS) of reinforced concrete buildings, and propose equations to derive floor acceleration design spectra (FDS) directly from the uniform hazard design spectra (UHS) for Montreal, Canada. The buildings used in the study are 27 existing reinforced concrete structures with braced frames and shear walls as their lateral load resisting systems: 12 are low-rise (up to 3 stories aboveground), 10 are medium-rise (4 to 7 stories), and 5 are high-rise (10 to 18 stories). Based on statistical and regression analysis of floor acceleration spectra generated from linear dynamic analysis of coupled building-NSC systems, two sets of modification factors are proposed to account for floor elevation and NSC damping, applicable to the experimentally-derived FDS for roof level and 5% NSC damping. Modification factor equations could be derived only for the low-rise and medium-rise building categories, as insufficient correlation in trends could be obtained for high-rises given their low number. The approach is illustrated in detail for two typical buildings of the database, one low-rise (Building #4) and one medium-rise (Building #18), where the proposed FDS/UHS results show agreement with those obtained from detailed dynamic analysis. The work is presented in the context of a more general methodology to show its potential general applicability to other building types and locations.
The National Research Council Canada is currently developing seismic evaluation and upgrading guidelines (SEG) for existing buildings in Canada. The SEG consist of both linear and nonlinear analysis ...procedures to evaluate the seismic adequacy of existing buildings. Where nonlinear analysis procedures are selected, nonlinear modelling parameters (NMP) and acceptance criteria (AC) are to be used. Due to the lack of Canadian guidelines for nonlinear analyses, the state of the practice in Canada often refers to ASCE/SEI 41 for guidance. Given the differences in seismic design and construction practices in the United States and Canada, ASCE/SEI 41 should be used with caution. This technical note presents a critical review of NMP and AC in ASCE/SEI 41 and recommends key steps for the investigation of the applicability of NMP and AC in ASCE/SEI 41 to the Canadian context. An example is included to demonstrate the recommended steps and the importance of such investigation.
► Research progress of micro- and meso-structure of RAC is introduced in the first part of this paper. ► The second part of this paper is devoted to the mechanical properties of recycled aggregate ...concrete material. ► The third part of the paper gives research on durability of RAC. ► The last part presents a review on the structural performance of RAC elements and structures.
A series of investigations on the mechanical property, durability, and the structural performance of recycled aggregate concrete (RAC) have been carried out in the past 15years (1996–2011) in China. The achievements of researches on recycled concrete are relatively sufficient to review and share with investigators from other countries. Some research progress of micro- and meso-structure of RAC is introduced in the first part of this paper. The second part of this paper is devoted to the mechanical properties of RAC material: strength, elastic modulus, Poisson’s ratio, stress–strain curve. The third part of the paper gives research on durability of RAC: carbonization, chloride penetration, shrinkage and creep. The last part presents a review on the structural performance of RAC elements and structures: beams, columns, slabs, beam–column joints, shear walls as well as frames made with RAC. Results of all researches reveal that with proper design and construction, it is safe and feasible to apply RAC as a structural material in civil engineering. Moreover, in this paper, the relevant research results of RAC obtained in China and from other countries are compared and discussed. This review provides helpful directions to those who are already engaged in this research, and points out areas which are needed to promote safe and economic use of RAC.
•Provide a state-of-the-art review of buckling restrained braces (BRBs).•Discuss the development and classifications of BRBs.•Outline the advantages and limitations of the various types of ...BRBs.•Explore some innovative applications of BRBs in earthquake-resistant design of buildings.
As an earthquake-resistant structural element, buckling-restrained brace (BRB) not only adds strength and stiffness but provides excellent energy absorption capability to a structure. Since its inception in the late 1980s, BRB has been the subject of research by many researchers. Different types of BRBs have been proposed for use to address miscellaneous structural requirements by researchers and practitioners primarily in Japan, U.S. and China. Research is continuing toward the development of BRBs that are more efficient, compact, lightweight, less expensive to fabricate and easier to install. This paper summarizes the development of BRBs in the past few decades including their history, classifications, applications and scientific research. A discussion on the advantages offered by different types of BRBs and some insights into the future prospects for BRBs are also given.
This paper describes the calibration of a phenomenological hinge model to simulate the nonlinear hysteretic response of reinforced concrete (RC) beam-columns under large deformations. The model is ...developed to enable simulation of the nonlinear dynamic response of RC frame buildings, from the initiation of damage to the onset of sidesway collapse, under earthquake ground motions. The model's monotonic backbone curve and hysteretic degradation rules capture post-peak in-cycle softening, combined with cyclic deterioration, which are associated with concrete crushing and reinforcing bar buckling at large cyclic deformations. The model calibration is based on experimental data for 255 rectangular RC columns with widely varying seismic design and detailing characteristics. For each of the 255 tests, the element model parameters, including initial stiffness, inelastic rotation limits, and cyclic energy dissipation capacity, are systematically calibrated to laboratory test data. Regression analyses are then used to develop semi-empirical equations to calculate the model parameters as functions of the column design parameters. The model parameters are calibrated in a statistically rigorous manner, where both median estimates and lognormal standard deviations are reported for each parameter. Important design parameters that affect the column model properties are the axial load ratio, confinement steel ratio, and spacing of confinement steel.
•AI-assisted simulation-driven framework for optimal earthquake-resistant design.•Traditional design parameters do not consider extensive plasticity in buildings.•Framework creates a database with a ...wide range of design inputs via NRHAs.•AI models trained to automatically output optimal design parameters.•ANN model yields optimal distribution of lateral force with < 1% error.
Traditional earthquake-resistant structural design considers only a limited number of factors, mainly elastic structural properties, to determine key design parameters. However, these parameters are often not optimal because they do not take into account the extensive plasticity expected in building structures during earthquakes. To address this issue, an artificial intelligence (AI)-assisted simulation-driven framework has been developed in this study. This framework can automatically output optimal design parameters while considering nonlinear structural response under strong earthquakes and a large number of input factors. The primary innovation of the proposed framework lies in the fusion and integration of nonlinear numerical simulation and AI tools for earthquake-resistant design of building structures, marking a promising trend in this field. The framework consists of two steps. In the first step, a database that consists of optimal design parameters and covers a wide range of design inputs will be created through numerical nonlinear response history analyses (NRHAs). In the second step, AI models will be created and trained based on the database to automatically output the optimal design parameters. To illustrate the basic components underlying the proposed framework, the determination of the height-wise distribution (denoted by Ψ) of the total design lateral force for a strong back system is taken as an example. A database of 1200 samples was created through NRHAs, and an artificial neural network (ANN) model was created, optimised, and trained. The developed ANN model yielded optimal Ψ with the majority of absolute errors within 1%, demonstrating the feasibility of the proposed AI-assisted simulation-driven earthquake-resistant design framework.
The use of precast concrete hollow-core floors rose to prominence in New Zealand in the 1980s because of an economic boom at that time and the ease of construction. Their widespread use in New ...Zealand, a region with high seismicity, and observations made after the 1994 Northridge Earthquake prompted a comprehensive research program to better understand the behavior of hollow-core floors in earthquakes. A number of system-level and component-level tests were conducted and results from this research program helped understand vulnerabilities of hollow-core floor systems and led to improvements in design provisions in the New Zealand Concrete Standard. The research program also provided the basis for the development of a seismic assessment procedure for existing hollow-core floors described in a companion paper. A summary of this research program and key design provisions is presented in this paper. Keywords: floor diaphragm; hollow-core floors; precast concrete; seismic testing.
