Preliminary Evaluation of the Impact of Eurocode 8 Draft Revision on the Seismic Zonation of Romania

This study is focused on the impact of the Eurocode 8 draft revision on the seismic zonation of Romania, one of the countries with the highest hazard levels in Europe. In this study, the design response spectra are evaluated for a number of sites in Romania for which both shear wave velocity profiles and ground motion recordings are available. The impact of the proposed changes on the structural design for structures situated in the southern part of Romania is also discussed. The results show considerable differences between the design response spectra computed according to the Eurocode 8 draft revision and the design response spectra from the current Romanian seismic code P100-1/2013. The differences are larger in the case of the sites situated in the southern part of Romania and those which have large design values for the control period TC. In Bucharest, for instance, it was found that the maximum design spectral accelerations would correspond to those from the 2006 version of the code while the maximum design spectral displacements would be significantly smaller than the levels produced by the 1981 or 1992 versions of the code. The results presented herein show that the differences in the seismic hazard and design ground motions are mainly due to the effects of local soil and site conditions and the associated site amplification proposed in the current Romanian seismic code and EC8 draft revision. Moreover, it has been shown that more analyses are needed to apply the seismic actions proposed in Eurocode 8 revision specifically for the sites in Romania under the influence of Vrancea intermediate-depth earthquakes so as to ensure an increased level of seismic safety for structures designed and built in the future.

Numerical analysis of safety distances of reinforced concrete structures subjected to blast loading by Perform-3D

Purpose The purpose of this study is to develop the performance model of buildings designed by the seismic code 2800 against the explosion wave and determination of safety distance. Design/methodology/approach Analytical models of three-, five- and ten story structures that used moment frame system and also a ten-storey building with shaer wall designed based on the seismic code 2800 in term of design and nonlinear analysis were generated for use with Perform-3D software. Extensive parametric analysis is executed on different explosive loads with 100, 500, 1,000 and 5,000 Trinitrotoluene, soil types 2 and 3, models eqs and eqbs, the number of story buildings and the effect of shear wall to determine the safety distance based on collapse threshold performance (CP) level criterion. Findings The results indicate that by increasing the explosives mass from 100 to 5,000 kg and the number of the stories three and five induce increasing the safety distance of CP level in buildings to 4.5 meter and 3 meter times, respectively. Ten-story structures modeled on shear wall show very good performance because of stiffness rising and high energy absorption. In addition, by increasing the stories from five to ten, the amount of the safety distance reduces the CP level to 3.9 meter times. Originality/value The results of this work are meaningful for explosion-resistant design and damage assessments of reinforced concrete moment framed structures subjected to explosive explosion.

Compliance-based estimation of seismic collapse risk of an existing reinforced concrete frame building

Seismic evaluation of existing structures is based on determining the damage likely to occur during the lifetime of these structures due to earthquake ground motion excitation. However, there is not a consensus about the acceptable level of seismic damage, the expected lifetime of these structures, and the seismic hazard level(s) to evaluate the structures at. This paper presents a methodology for a parametric calculation of the seismic collapse risk of an existing Reinforced Concrete (RC) frame building based on its seismic code compliance, quantified by a dimensionless metric. This metric, defined as compliance factor, compares the seismic capacity of an existing structure with the seismic demand for a new structure at a predetermined hazard level. The inelastic seismic behavior of four models of the RC frame building of varying compliance was analytically investigated in this study to demonstrate the novel methodology. The four models of the RC building were chosen to represent existing RC frame structures designed and constructed before the introduction of modern seismic code provisions. These four building models were excited by a group of earthquake ground motion excitations using Incremental Dynamic Analysis. The collapse probabilities of the four building models, representing varying values of seismic code compliance, were determined for two different locations corresponding to regions of moderate and high seismic hazard, thus laying the basis for the compliance-based estimation of the seismic collapse risk of existing structures.

Influence of Chained Masonry on the Seismic Response of Reinforced Concrete Buildings

The influence of chained masonry walls, which represents a special case of masonry infill without gap, on the seismic response of reinforced concrete buildings is extremely important due to their wide use in this type of building. We can consider the period of building as the key parameter to study this influence. In this article, we had carried out a comparative study of several 2D models of a multi-storey reinforced concrete building with a brick chained masonry wall using the response spectrum method in the ETABS finite element software, following the prescriptions of the current Algerian seismic code. This study included the use of the number of spans, the span length, the number of storeys, the thickness of the chained masonry wall, the ground soft storey, the openings in the walls, and the short column for studying the influence of these to the walls. The values from the numerical simulation were compared with those from the formula of the period of building, provided by both the Algerian and European codes. Based on the results obtained, we were able to assess the influence of chained masonry walls on the seismic response on this type of buildings. Through this article, we have concluded that these walls have a great influence on the overall behavior of reinforced concrete buildings under seismic loading. HIGHLIGHTS Clarify the importance of numerical simulation of chained masonry walls in the design of reinforced concrete buildings Give recommendations to the current Algerian seismic code for properly design the infilled buildings with chained masonry Know the great danger marked in the current conceptions, which neglect these walls in the phase of conception Give to the infilled reinforced concrete buildings an adequate design in case of earthquake loadings GRAPHICAL ABSTRACT

SEISMIC ASSESSMENT OF CONTEMPORARY VERSUS OLD URBAN FRAME BUILDINGS

This comparative study probabilistically assesses the relative safety margins of code-compliant and pre-seismic code RC buildings with different heights in a region of medium seismicity. Detailed structural design and fiber-based modeling of six benchmark structures, namely two code-compliant buildings and two pre-code structures before and after retrofit, are undertaken to develop fragility functions using several earthquake records representing the most critical seismic scenario in the study area. Several inelastic dynamic analyses are performed to assess the seismic response and derive a range of fragility functions for the six benchmark buildings. Compared with contemporary structures, the study highlights the vulnerability of pre-code buildings due to the insufficient stiffness, strength, and ductility provided by their lateral force resisting systems. A practical retrofit solution for pre-code structures is subsequently assessed using the methodology adopted for other modern and old buildings. The probabilistic assessment results confirmed the comparable seismic performance of the retrofitted and code-conforming buildings. The comparative study, which provided insights into the differences between code-compliant versus pre-seismic code buildings before and after retrofit, contributes to reducing earthquake losses and improving community seismic resilience in earthquake-prone regions.

COMPARATIVE SEISMIC PERFORMANCE ASSESSMENT OF UHPC JACKETING AND SCED BRACING TECHNIQUES

Observed damage to existing pre-seismic code buildings in previous earthquakes has raised interest among the engineering community for improving the performance of these structures using different seismic retrofit measures. This paper throws light on contemporary techniques for the seismic retrofit of RC buildings, namely ultra-high-performance concrete (UHPC) jacketing and self-centering energy dissipative (SCED) braces. Detailed fiber-based numerical modeling of a benchmark structure is undertaken to evaluate the effectiveness of the selected retrofit measures. The case study structure is a two-story pre-seismic code residential building designed for gravity and wind loads, exhibiting poor seismic performance. Along with the two retrofit strategies investigated, several parameters are also considered. Inelastic static pushover and incremental dynamic analyses are conducted to select the retrofit measures and assess their effects on seismic performance. Using a collection of far-field earthquake records and a set of performance criteria, fragility functions are constructed to assess the vulnerability of the benchmark structure with and without the retrofit solutions. The study shows that the adopted index that links cost to the seismic performance obtained from the fragility functions can provide a rational ranking of the selected retrofit approaches relative to the existing building and support selecting the most effective and economical alternative.

A novel inter-story drift limit proposal for TBEC2018 and fragility prognosis with TSC2007

The basic purpose of this paper is to investigate and propose a novel inter-story drift limits for the current Turkish Seismic Code to get easy structural assessment by using software. For this aim, numerical analysis was performed by modeling two types of RC frame structures. One of them is 5 stories, the other of them is 7 stories. Two different concrete classes, C20 and C25, were considered and three tension reinforcement ratios were considered for analysis. Tension reinforcement ratios were determined by half of the compressive reinforcement, equal to compressive reinforcement and double the compressive reinforcement ratio. Incremental dynamic analyses (IDA) were performed on these buildings. In this study to execute IDA, eleven seismic acceleration benchmark records were multiplied with various scaling factors from 0.2 to 1.0. Maximum base shear and corresponding roof displacement responses obtained from IDA curves were generated according to these responses. IDA curves were compared with each other by deriving fragility graphs. According to results, proposed limits for the current Turkish seismic code (TBEC-2018) provide, 0.6%, 2.4% and 3.3% respectively for MN, GV and GC, rather safe limits compared to drift limits presented in the foredate seismic code (TSC-2007).

Comparative Study of Indonesian Spectra Response Parameters for Buildings According To 2012 and 2019 Seismic Codes

The Indonesian government has determined a new seismic code for structural design of buildings and non-buildings, namely SNI 1726:2019. This new code is a revision of the previous code of 2012. The fundamental difference between the two seismic codes of 2012 and 2019 is in the earthquake hazard map (EHM) that was used. 2012 seismic code uses the EHM-2010, while 2019 seismic code uses the EHM-2017. The EHM-2017 has been updated by revising a data of subduction parameters and updating the number of active faults from 81 to 251. This revision has an impact on increasing the spectral value of SS and S1 which is a parameter that must be reviewed in structural planning. This study investigated the seismicity status of 34 cities in Indonesia by comparing the values of the spectra response parameters (SDS and SD1) according to seismic code of 2012 and 2019. This study found that the SDS and SD1 value from 2012 to 2019 increased in 15 cities but decreased or remained in 19 other cities. The cities that experienced an increase of SDS and SD1 values were Bandar Lampung, Banjarmasin, Bengkulu, Gorontalo, Jayapura, Manokrawi, Medan, Palembang, Palu, Pangkal Pinang, Pontianak, Serang, Surabaya, Tanjung Selor, and Yogyakarta. It seems that the vulnerability assessment of the existing building in the 15 cities must be done to estimate their capacity under earthquake load designed by 2019 Seismic Code. Overall, Jayapura city has the highest of SDS and SD1 values in 2019 compared to the other cities.