20 research outputs found
ANALYTICAL STUDY OF ACCEPTANCE CRITERIA FOR RETROFITTED BEAMS WITH FRP USING NUMERICAL MODELING
No full textIn recent decades, composite material has been used in order to increase the effectiveness of reinforced concrete structures. The difficulty of numerical modeling of beams in finite element method is a problem encountered during such a study. Destruction of structures such as buildings and bridges has been reported due to earthquake and time-dependent erosion. Highlighting the need for reinforcing the structures, many researchers have tried to estimate the efficiency limit and strength of reinforced concrete structures.In order to retrofit concrete structures polymer coating was first developed in Europe and Japan in 1980. In Europe, FRP systems have been used to replace steel sheets, that as a common resisting method, their connection to the tensile concrete parts of the members with different adhesives was popular to increase the flexural strength of the members. Since steel sheets deform under operation, they would destroy the connection of sheets and concrete. On the other hand, their installation is generally difficult and needs heavy machinery, so researchers sought a replacement of steel coatings with FRP. FRP with 20\% weight of steel jackets is approximately 8 to 10 times stronger than steel. One of the problems of numerical studies in these systems is their computer modeling in the form of finite element analysis (FEM). On the other hand due to a variety of effective parameters on their behavior, applying lab methods causes problems as they are time-consuming and expensive.In this research, retrofitting reinforced concrete beams using FRP is studied. At first in order to validate the accuracy of modeling, the analysis results obtained by ABAQUS software are compared with those of experimental studies. Then, beams that need strengthening are retrofitted and the effect of FRP on the curvature and rotational capacity of these beams is investigated. Finally, ductility proportion to the performance levels and the acceptance criteria for retrofitted beams regarding force or displacement control scenarios are obtained. Based on the results, the behavior of beams changes after retrofit, and since the displacement demand to capacity ratio (DCR) is less than 2, force control scenario must be considered regarding their acceptance criteria
COMPARING BLAST LOAD BEHAVIORS OF REHABILITATED CONCRETE STRUCTURES USING VISCOUS DAMPER AND BASE ISOLATOR
No full textThe buildings structures around the world suffer from terrorist attacks and
bombings. This justifies the need to study the effect of blast loading on structures and the methods to prevent collapse of structures in order to save human lives and minimize financial losses. In this study, effects of the passive viscous dampers and base isolators on structures which are subjected to blast loading are separately investigated. Blast load is applied on the structures with a pressure wave. This pressure wave has many uncertainties specified in different codes. For the sake of simplicity, this pressure wave is applied on different faces of the structure. Herein, only loading on the fa\c{c}ade or the structure is considered and the loading on the other faces of the structure are neglected as the structure doesn't have any severe irregularities. In the 1st case, viscous dampers are added to the structure adding damping of the structure between 5 to 25\% and the effect of this added damping is studied through the paper. For the 2nd case, base isolators are designed according to UBC-1997 code. Numerical simulations are carried out in the SAP environment using nonlinear time-history analysis. Moreover, they are studied with different stiffness coefficients and the uncertainties in yielding force of these tools have been considered in numerical simulations. These passive control devices are mainly designed such that they can perform well under earthquake loads. Viscous dampers conform to the first mode of vibration of the structure and base isolators are designed according to seismic codes. Numerical simulations show that base shear in the optimum specifications of viscous dampers and base isolators compared to bare frame showed 60\% increase and 50\% decrease, respectively. However, drifts are minimized to 1.7\% for added damping values of 25\%. This value is hard to reach with base isolators as the values of drifts in this case have a minimum value of 2\%
Table size effect on wind resistance of modified bituminous roofing systems
No full textPeer reviewed: YesNRC publication: Ye
Numerical Evaluation for the Effect of Table Size on Roof Wind Uplift Resistance. Part 1: Thermoplastic Roofing Systems
No full textThe objective of the present study is to investigate numerically, the effect of table size on the roofing system response. A commercially available Finite Element program, ABAQUS version 5.8, with non-linear analysis capability was used to carry out all the analyses. Details of the adopted model, benchmarking of the developed model with experimental data and procedure used to derive correction factors are reported by Baskaran, A., Zahrai, S. M. and Chen, Y in a technical paper entitled, "Numerical Evaluation of Roofing Systems for Wind Uplift Pressures'. This report archives all the results for the fastener loads obtained from the numerical analyses. Thermoplastic assemblies with TPO and PVC membranes were considered. To study the effect of table size, simulations were performed for the variations of the two influencing factors, namely, fastener row spacing (Fr) and fastener spacing (Fs). Three Fr, configurations 1830, 1700 and 1220 mm (72", 67" and 48) with three Fs, configurations 152,305 and 460 mm (6, 12" and 18) were considered. Fifteen simulations were performed for each configuration by varying the table width. Computed fastener loads are given in Tables 2 to 5. In highlighted form, Appendix A provides examples of input files with the respective output files. Coordinates of the all the required files for the presented simulations are tabulated in Appendix B.La pr\ue9sente \ue9tude a pour objet l?investigation num\ue9rique de l?incidence des dimensions de la table d?essai sur la r\ue9ponse du syst\ue8me de couverture. Un programme commercial de mod\ue9lisation par \ue9l\ue9ments finis, ABAQUS, version 5.8, dot\ue9 d?une capacit\ue9 d?analyse non lin\ue9aire, a \ue9t\ue9 utilis\ue9 aux fins de la r\ue9alisation de toutes les analyses. Les d\ue9tails du mod\ue8le adopt\ue9, de l?\ue9valuation des performances du mod\ue8le d\ue9velopp\ue9 en fonction des donn\ue9es exp\ue9rimentales et de la proc\ue9dure utilis\ue9e pour d\ue9river des facteurs de correction sont expos\ue9s par Baskaran, A., Zahrai, S. M. et Chen, Y. dans un document technique intitul\ue9 Numerical Evaluation of Roofing Systems for Wind Uplift Pressures. Ce rapport archive tous les r\ue9sultats obtenus relativement aux charges attribuables aux attaches, d\ue9coulant des analyses num\ue9riques. Les ensembles thermoplastiques avec rev\ueatements d?\ue9tanch\ue9it\ue9 en TPO et en PVC ont \ue9t\ue9 \ue9tudi\ue9s. Afin d?examiner l?incidence des dimensions de la table d?essai, des simulations ont \ue9t\ue9 faites des variations des deux facteurs d\ue9terminants, notamment l?espacement des rangs d?attaches (Fr) et l?espacement des attaches (Fs). Trois configurations Fr, soit de 1830 mm, de 1700 mm et de 1220 mm (72 po, 67 po et 48 po) et trois configurations Fs, soit de 152 mm, de 305 mm et de 460 mm (6 po, 12 po et 18 po) ont \ue9t\ue9 prises en compte. Quinze simulations ont \ue9t\ue9 faites pour chacune des configurations, par variation de la largeur de la table. Les tableaux 2 \ue0 5 fournissent les valeurs des charges calcul\ue9es pour les attaches. En caract\ue8res rehauss\ue9s, l?annexe A fournit des exemples de fichiers d?entr\ue9e avec leurs fichiers de sortie respectifs. Les coordonn\ue9es de tous les fichiers requis pour les simulations pr\ue9sent\ue9es sont tabul\ue9es dans l?annexe B.Peer reviewed: NoNRC publication: Ye
Numerical evaluation of roofing systems for wind uplift pressures
No full textPeer reviewed: YesNRC publication: Ye
Multi‐objective design and performance investigation of a high‐rise building with track nonlinear energy sinks
No full textSensitivity Analysis of Tubular-Web Reduced Beam Section Connections Under Cyclic Loading
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