Ductility of RC Columns due to Strong Near Source Earthquakes

Near source earthquakes can produce strong vertical ground motions with large amplitude and high frequency content. In this paper the axial ductility behavior of RC columns due to near source earthquakes is investigated. The column is simplified to a SDOF system that only describes vertical vibrations of a structural column. The gravity load effect is represented by a pre-load. An elasto-plastic model accounting for different stiffness and strength in tension and compression is used in the analysis. The ductility demand as well as pseudo acceleration spectra are evaluated. The investigation shows that strong vertical ground motions should be considered in seismic design. From the results of this investigation suggestions for a seismic design in case of near source earthquakes can be derived

Building and bridge pounding damage observed in 2011 Christchurch earthquake

This paper describes pounding damage sustained by buildings and bridges in the February 2011 Christchurch earthquake. Approximately 6% of buildings in Christchurch CBD were observed to have suffered some form of serious pounding damage. Almost all of this pounding damage occurred in masonry buildings, further highlighting their vulnerability to this phenomenon. Modern buildings were found to be vulnerable to pounding damage where overly stiff and strong ‘flashing’ components were installed in existing building separations. Soil variability is identified as a key aspect that amplifies the relative movement of buildings, and hence increases the likelihood of pounding damage. Pounding damage in bridges was found to be relatively minor and infrequent in the Christchurch earthquake

Performance of a natural fibre reinforced polymer-concrete bridge pier in earthquakes

Glass or carbon fibre reinforced polymers are extensively used in the automobile and the aerospace industries. However, in civil infrastructure their usage is mainly limited to retrofitting, because synthetic fibres are expensive. Steel is heavy, expensive and subject to corrosion. Instead of steel reinforcement in civil structures the usage of natural materials will reduce the total mass and cost of the structures and circumvent the long-term problem of corrosion. In this paper flax fibre reinforced polymer (FFRP) and coconut fibre reinforced concrete (CFRC) are investigated. Because of the usage of less mass the corrosion-free composite structures will experience less effect of dynamic loads and require less running maintenance. The seismic performance of a simple bridge pier made of FFRP-CFRC composite is presented. The earthquake loading is simulated by a shake table. The results indicate that the new composite has a potential for becoming resilient construction materials for future structures

Bumpers for reducing the effect of pounding between bridge decks

The study addresses the influence of bumpers as reduction measures at the bridge decks. The considered devices are steel spring, steel spring with additional viscous damper or steel spring with additional friction element. Gap between bridge decks remains. The reduction measure is placed at one end of the neighbouring girders. The considered earthquakes are the 1994 Northridge earthquake and the 1995 Kobe earthquake. For the nonlinear analysis a finite element method is used. The investigation shows that compared to the other measures the best reduction of the pounding force can be achieved with a friction device

Macerated-Pineapple Core Crude Extract-derived Bromelain Has Low Cytotoxic Effect in NIH-3T3 Fibroblast

BACKGROUND: Bromelain is a sulfhydryl proteolytic enzyme that can hydrolyze protein, protease or peptide. Bromelain can be found in pineapple stem, fruit and core. Bromelain is composed of 212 amino acid residues with cysteine-25 forming a polypeptide chain that can hydrolyze peptide bonds by H2O. In medicine, bromelain has been developed as antibiotic, cancer drug, anti-inflammatory agent and immunomodulator. In dentistry, bromelain has potential to reduce plaque formation on the teeth and to irrigate root canal.METHODS: Pineapple core was dried for 3 days to get simplicia. Then simplicia was extracted with water solvent for 24 hours. After that, the macerated-pineapple core crude extract-derived bromelain (PCB) was separated by Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) followed by Coomassie Brilliant Blue (CBB) staining to ensure the presence of bromelain. In cytotoxic test, NIH-3T3 fibroblast cultures were treated with extracts in various concentrations to for 24 or 48 hours. Number of fibroblasts was calculated using 3-(4,5-dimethylthiazol-2- yl)-2,5-Diphenyltetrazolium bromide (MTT) assay.RESULTS: Pineapple core extraction using maceration method produced relative high yield (concentration: 1.5424 g/mL) of bromelain, which was confirmed by CBB staining results with the molecular weight of 33 kDa. Based on cytotoxic test results of PCB on NIH-3T3 fibroblasts, 24-hours-incubation LD50 was 95.7 g/L, while 48-hours-incubation LD50 was 51.1 g/L.CONCLUSION: PCB has low cytotoxic effect in NIH-3T3 fibroblasts

Damage-based seismic planar pounding analysis of adjacent symmetric buildings considering inelastic structure-soil-structure interaction

In cities and urban areas, building structures located at close proximities inevitably interact under dynamic loading by direct pounding and indirectly through the underlying soil. Majority of the previous adjacent buildings pounding studies that have taken the Structure-Soil-Structure Interaction (SSSI) problem into account have used simple lumped mass-spring-dashpot models under plane-strain conditions. In this research, the problem of SSSI-included pounding problem of two adjacent symmetric in plan buildings resting on a soft soil profile excited by uniaxial earthquake loadings is investigated. To this end, a series of SSSI models considering one-directional nonlinear impact elements between adjacent co-planar stories and using a method for direct FE modeling of 3D inelastic underlying soil volume have been developed to accurately study the problem. An advanced inelastic structural behavior parameter, the seismic damage index, has been considered in this study as the key nonlinear structural response of adjacent buildings. Based on the results of SSSI and fixed-base cases analyses presented herein, two main problems are investigated, namely, the minimum building separation distance for pounding prevention and seismic pounding effects on structural damage in adjacent buildings. The final results show that at least three times the IBC 2009 minimum distance for building separation recommended value is required as a clear distance for adjacent symmetric buildings to prevent the occurrence of seismic pounding. At the IBC recommended distance, adjacent buildings experienced severe seismic pounding and therefore significant variations in storey shear forces and damage indices. <br clear="none"/

Damage Identification of Unreinforced Masonry Panels Using Vibration-Based Techniques

Several damage indicators based on changes in modal properties validated for homogeneous materials were applied to detect damage in an unreinforced masonry cantilever panel. Damage was created by a “clean diagonal cut” at the center of the specimen which length was progressively extended towards the specimen’s corners. Numerical simulations were employed to determine the modal response at several damage states and this data was used to calculate the damage indicators. Those indicators presenting a good performance were then applied to identify damage on a physical specimen tested in the laboratory. The outcomes of this study demonstrated that vibration-based damage detection in unreinforced masonry structures can be satisfactorily performed. However, the identification of the damage spatial distribution using vibration-based methods in unreinforced masonry structures is still difficult. To improve the prediction of damage distribution, a large number of measurement points need to be considered to obtain an acceptable level of resolution

Damage identification of unreinforced masonry panels using Vibration-Based Techniques

Several damage indicators based on changes in modal properties validated for homogeneous materials were applied to detect damage in an unreinforced masonry cantilever panel. Damage was created by a “clean diagonal cut” at the center of the specimen which length was progressively extended towards the specimen’s corners. Numerical simulations were employed to determine the modal response at several damage states and this data was used to calculate the damage indicators. Those indicators presenting a good performance were then applied to identify damage on a physical specimen tested in the laboratory. The outcomes of this study demonstrated that vibration-based damage detection in unreinforced masonry structures can be satisfactorily performed.However, the identification of the damage spatial distribution using vibration-based methods in unreinforced masonry structures is still difficult. To improve the prediction of damage distribution, a large number of measurement points need to be considered to obtain an acceptable level of resolution

Resilient Civil Infrastructure under Dynamic Loadings

A resilient infrastructural system is an important component of a modern city. The main principles are safety, sustainability, functionality, maintainability, and fast recoverability following natural and/or man-made hazards. This special issue addresses new research developments in resilient infrastructural systems under dynamic loadings, for example, wind, traffic, tsunamis, and earthquakes

PENGARUH CELEBRITY ENDORSEMENT TERHADAP NIAT PEMBELIAN YANG DIMEDIASI OLEH KESADARAN MEREK STUDI PADA PRODUK SOMETHINC

Penelitian ini dilakukan dengan tujuan untuk menguji pengaruh celebrity endorsement terhadap niat pembelian dengan memediasi kesadaran merek pada produk Somethinc. Jumlah responden yang memenuhi kriteria penelitian ini adalah sebanyak 162 responden. Metode pengambilan sampel dalam penelitian ini adalah purpoisive sampling dengan menggunakan skala likert 5 poin yang dikumpulkan melalui Google Form. Data sampel yang terkumpul diolah menggunakan SPSS dengan menggunakan metode analisis regresi dan analisis mediasi. Hasil dari penelitian ini menunjukkan bahwa variabel celebrity endorsement mempengaruhi niat pembelian, celebrity endorsement mempengaruhi kesadaran merek, kesadaran merek mempengaruhi niat pembelian, dan kesadaran merek memediasi pengaruh celebrity endorsement terhadap niat pembelian