This paper addresses the efficiency of thermal insulation layers applied to protect structural elements strengthened by fiber-reinforced polymers (FRP) in the case of fire event. The paper presents numerical modeling and nonlinear... more
This paper addresses the efficiency of thermal insulation layers applied to protect structural elements strengthened by fiber-reinforced polymers (FRP) in the case of fire event. The paper presents numerical modeling and nonlinear analysis of reinforced concrete (RC) columns externally strengthened by FRP and protected by thermal insulation layers when subjected to elevated temperature specified by standard fire tests, in order to predict their residual capacity and fire endurance. The adopted numerical approach uses commercial software includes heat transfer, variation of thermal and mechanical properties of concrete, steel reinforcement, FRP and insulation material with elevated temperature. The numerical results show good agreement with published results of full-scale fire tests. A parametric study was conducted to investigate the influence of several variables on the structural response and residual capacity of insulated FRP-confined columns loaded by service loads when exposed ...
In many countries, buildings are usually made of unreinforced clay masonry walls, especially in Colombia. These constructions have low resistance and ductility, and are very vulnerable to seismic events, due to their low capacity of... more
In many countries, buildings are usually made of unreinforced clay masonry walls, especially in Colombia. These constructions have low resistance and ductility, and are very vulnerable to seismic events, due to their low capacity of energy dissipation. This paper reports the results obtained from a research project that evaluates the behavior of reinforced masonry walls under lateral loads. The reinforcement was made using Carbon Fiber Reinforced Polymers (CFRP). In the test program, eight (8) clay masonry walls were built using hollow brick. Four (4) of them were 1,23 m long and 1,90 m high and the remaining four (4) were 2,47 m long and 1,90 m high. Four (4) walls were tested with a static lateral load and four (4) with a cyclic lateral load in its plane. Results revealed that the presence of the reinforcement material significantly increased the ultimate load and deformation capacity, provided that the material has a suitable anchoring system.
The premature failure problem of beams strengthened with external plates reduces its efficiency. Although this problem is considered in different experimental and analytical studies, more effort is required to increase the... more
The premature failure problem of beams strengthened with external plates reduces its efficiency. Although this problem is considered in different experimental and analytical studies, more effort is required to increase the efficiency of such expensive strengthening technique. As part of a comprehensive program, this experimental study i s applied on eleven continuous reinforced concrete (R .C ) beams and nine full -scale simply supported R.C beams. The effect of using different materials and schemes for external reinforcing was investigated on the overall behavior of the strengthened beams. Behavior of beams strengthened with the proposed schemes was explored considering its practicality and cost of strengthening. The ultimate load of the tested beams were compared with the design load calculated using the ACI 440-02 guidelines for external flexure and shear strengthening of beams. Generally, controlling the shear cracks propagation by using web plates and reducing stress concentration and crack propagation along the strengthening plate delays the premature mode of failure and correspondingly enhances significantly the strengthened beam’s capacity and ductility. Due to their significant effect, different common strengthening schemes need to be considered in any proposed design guidelines for more economic and reliable applications.
The noncorrosive fiber-reinforced polymer (FRP) composite bars are an excellent alternative reinforcement. In this paper, a review of the available punching load equations of two-way FRP-reinforced slabs and shear strength equations of... more
The noncorrosive fiber-reinforced polymer (FRP) composite bars are an excellent alternative reinforcement. In this paper, a review of the available punching load equations of two-way FRP-reinforced slabs and shear strength equations of one-way FRP-reinforced slabs are provided. All the models were verified against results for test specimens from the literature. The equivalent steel ratio model of Theodorakopoulos and Swamy produced the best estimates for the punching load while the model of Deitz, Harik, and Gesund yielded the best predictions of shear capacity. One of the punching strength models was modified in the current research and it gave excellent results. Using this modified model it is proved that the increase in the reinforcement ratio is accompanied by an increase in the punching strength.
Objectives. This study aimed to investigate physical properties of a fiber-reinforced CAD/CAM resin disc, which included woven layers of multi-directional glass fibers. Methods. Fiber orientations of CAD/CAM specimens (TRINIA, SHOFU) were... more
Objectives. This study aimed to investigate physical properties of a fiber-reinforced CAD/CAM resin disc, which included woven layers of multi-directional glass fibers. Methods. Fiber orientations of CAD/CAM specimens (TRINIA, SHOFU) were specified as longitudinal (L), longitudinal-rotated (LR), and anti-longitudinal (AL). A fiber-reinforced composite (everX posterior, GC (E)) and a conventional composite (Beauti core flow paste, SHOFU (B)) were also tested. A three-point bending test and a tensile test with notchless prism-shaped specimens were conducted using a universal testing machine (AUTOGRAPH AG-IS, Shimadzu). A water absorption test was also carried out after the specimens were stored in water for 24 h or 1 week. Flexural strength and fracture toughness were obtained by conducting a three-point bending test. Results. TRINIA L and LR groups showed significantly high flexural strength (254.2 ± 22.3 and 248.8 ± 16.7 MPa, respectively). Those were approximately 2.5 times higher than those in AL, E, and B groups (96.8-98.0 MPa) (p < 0.05, ANOVA and Tukey HSD test). No significant difference was shown in flexural modulus among the experimental groups. The fracture toughness in L group (9.1 ± 0.4 MPa/m 1/2) was found to be significantly higher than those in other groups (1.9-3.0 MPa/m 1/2 ; p < 0.05). TRINIA group demonstrated significantly lower water absorption (4.7 ± 1.9 g/mm 3) than did E (16.1 ± 3.1 g/mm 3) and B (17.3 ± 3.7 g/mm 3) groups (p < 0.05). Significance. TRINIA demonstrated distinct anisotropy. TRINIA can be used as a superior restorative material when specifying directions of its fiber mesh layers.
Steel needle gates which are being used in Kolhapur Type Weirs (K.T. weirs) need to be replaced to overcome their disadvantages like heavy weight, corrosive nature, maintenance cost etc. Fiber Reinforced Plastic (F.R.P.) having advantages... more
Steel needle gates which are being used in Kolhapur Type Weirs (K.T. weirs) need to be replaced to overcome their disadvantages like heavy weight, corrosive nature, maintenance cost etc. Fiber Reinforced Plastic (F.R.P.) having advantages like light weight, low maintenance cost, corrosion resistance, longer service life etc. can be thought of as a replacement to steel in K.T. Weirs. In the present investigation an attempt is made to analyze the FRP Needle gates using finite element method. A generalized software tool is developed using FORTRAN which gives structural responses (deflections, stresses) as a result by input of material properties
Using externally bonded Fiber Reinforced polymer (FRP) laminate has become a well established solution for strengthening Reinforced Concrete (RC) beams in flexure and shear. However, the commonly observed premature modes of failure,... more
Using externally bonded Fiber Reinforced polymer (FRP) laminate has become a well established solution for strengthening Reinforced Concrete (RC) beams in flexure and shear. However, the commonly observed premature modes of failure, limits the gain of capacity for the beams strengthened in flexure. In this research work, the role of the shear strengthening existence on this premature mode of failure will be explored using different strengthening schemes and loading setups. Specimens were strengthened in flexure and shear with externally bonded fiber reinforced polymer (FRP) based on the ACI-440 guidelines for design of externally strengthened beams. In addition, numerical model -based on Finite Element Method (F.E.M) - is provided for further study of strengthening schemes. It’s found that controlling the crack propagation along the beam web by bonding shear strengthening continuous laminate, rather than narrow strips reducing the risk of the common premature modes of failure with bonding external laminate for flexure strengthening. ACI-440 guidelines need to consider more applicable and efficient shear strengthening schemes in addition to provide suitable formulation to account for the effect of loading setups, in which the interference between shear force and high bending moment (e.g. 3-point loading), on premature modes of failure exists.
"The random nature of the explosion load, associated with the random nature of material properties, and geometric dimensional characteristics, implies the need to consider them into the analysis in order to have a more correct estimation... more
"The random nature of the explosion load, associated with the random nature of material properties, and geometric dimensional characteristics, implies the need to consider them into the analysis in order to have a more correct estimation of the structural behavior. Therefore, when the randomness of these parameters in the analysis is considered, the response of the structure assumes probabilistic nature, and this makes it necessary to look into the reliability measure.
This paper presents results from a parametric investigation of the reliability of reinforced concrete (RC) beam subjected to blast load. The probabilistic responses of the maximum displacement for a reinforced concrete flexural member under blast loadings are evaluated by means of nonlinear dy-namic analysis with simplified equivalent single-degree-of-freedom (SDOF) system.
Results of numerical simulations have shown the response of structures, in terms of maximum dis-placement in relation also to the blast load and the geometrical and mechanical characteristics of the beams. Monte Carlo simulation of dynamic response of the equivalent SDOF system is performed to estimate the reliability."
