... The FRP lamination schedule for this specimen was similar to the carbon/epoxy strengthened sp... more ... The FRP lamination schedule for this specimen was similar to the carbon/epoxy strengthened specimens described earlier. After applying the composites, the composites material was allowed to cure for at least 72 hours under the laboratory environment. ...
Results of a pilot study on developing structural repair techniques for damaged steel beam-to-col... more Results of a pilot study on developing structural repair techniques for damaged steel beam-to-column connections using both conventional and unconventional systems are presented. The primary repair system developed in this study is in the form of 3-D braided graphite/epoxy composite connectors attached to the flanges of both beams and columns. Two composite repair details were investigated: (i) with high-strength/high-toughness adhesively bonded composite stiffeners, and (ii) with mechanically fastened composite stiffeners. The specimens were tested under both quasi-static and cyclic loading conditions. In addition, a novel adhesively bonded steel stiffener was developed and tested. The results were compared to those obtained from testing the welded control specimens. The adhesive repair system provided several desired features such as: minimum construction time, ease of applications, minimizing the use of heavy equipment, minimizing the use of holes and bolts, and eliminating the use of welding and the associated fire hazards to occupied facilities. Results obtained are encouraging. (a) For the covering entry of this conference, please see ITRD abstract no. E204495.
23rd Annual International Conference on Composites or Nano Engineering (ICCE23), 2015
This paper presents a summary of preliminary results obtained from an experimental investigation ... more This paper presents a summary of preliminary results obtained from an experimental investigation on the behavior of web-flange junctions of pultruded glass fibre-reinforced polymer (GFRP) I-profiles. In particular, the aim of the study is to suggest simple stiffening and strengthening element to improve the axial flexibility and strength of the junctions. Digital image correlation technique was used to capture in plane displacements and strains of the specimens
This paper presents results of an experimental study that focuses on monitoring changes in dynami... more This paper presents results of an experimental study that focuses on monitoring changes in dynamic characteristics of a damaged and retrofitted two-story reinforced concrete (RC) building model with poor detailing. In the study, ambient vibration tests are performed via four test setup protocols in order to monitor changes in dynamic characteristics before and after such setups. The four main test setups are: (i) undamaged (as-built) case (Setup # 1), (ii) damaged cases with different degrees of damages (Setup # 2), (iii) repaired case with different types of repair methods (Setup # 3), and (iv) strengthened case with externally bonded CFRP composite laminates (Setup # 4). In addition, a total of eight ambient vibration tests are conducted in order to assess the effects of degree of damage and associated retrofit systems on building’s dynamic characteristics such as natural frequencies, mode shapes, and damping ratios. The Stochastic Subspace Identification (SSI) Method is used to identify the dynamic characteristics. Experimentally identified dynamic characteristics obtained from all setups are compared with each other in order to detect the effect of damage and repair applications on the structure’s dynamic characteristics. Moreover, Modal Assurance Criterion (MAC) and Coordinate Modal Assurance Criterion (COMAC) are determined to examine the changes of stiffness of each RC building model.
Abstract The use of an innovative type of perfobond rib (PBL) shear connector in steel–concrete j... more Abstract The use of an innovative type of perfobond rib (PBL) shear connector in steel–concrete joints of hybrid girder bridges has gained wide popularity among bridge engineers. For a PBL group with multi-row PBLs in tandem arrays, comprehensive interactions exist among the connectors. However, the current design approaches assume that the force transferred by each row of PBL is uniform, resulting in an overestimated shear resistance of the connector group. The main objective of this paper is to introduce a mathematical approach, which accounts for the bonding-friction effects (BF) at the perforated steel plate/concrete slab interfaces and the reinforced concrete dowel (RD) effects by the perfobond hole, to assess the ultimate resistance of PBL group under the RD fracture failure mode. In this study, six push-out specimens for different PBL groups, with varying connectors’ quantity, were evaluated experimentally to determine the key parameters for the proposed analytical model. The experimental results revealed the significant reduction in average resistance of single PBL in a connector group as connector number increased. The proposed approach is validated by an experimental database that includes push-out test results obtained from the previously published studies and afterwards converted to the design load level, which can be extensively applied to the PBL group using normal concrete and ultra-high performance concrete (UHPC). The proposed analytical approach provides an efficient tool for analyzing and designing of PBL group in steel–concrete joints of hybrid girder bridges.
... The FRP lamination schedule for this specimen was similar to the carbon/epoxy strengthened sp... more ... The FRP lamination schedule for this specimen was similar to the carbon/epoxy strengthened specimens described earlier. After applying the composites, the composites material was allowed to cure for at least 72 hours under the laboratory environment. ...
Results of a pilot study on developing structural repair techniques for damaged steel beam-to-col... more Results of a pilot study on developing structural repair techniques for damaged steel beam-to-column connections using both conventional and unconventional systems are presented. The primary repair system developed in this study is in the form of 3-D braided graphite/epoxy composite connectors attached to the flanges of both beams and columns. Two composite repair details were investigated: (i) with high-strength/high-toughness adhesively bonded composite stiffeners, and (ii) with mechanically fastened composite stiffeners. The specimens were tested under both quasi-static and cyclic loading conditions. In addition, a novel adhesively bonded steel stiffener was developed and tested. The results were compared to those obtained from testing the welded control specimens. The adhesive repair system provided several desired features such as: minimum construction time, ease of applications, minimizing the use of heavy equipment, minimizing the use of holes and bolts, and eliminating the use of welding and the associated fire hazards to occupied facilities. Results obtained are encouraging. (a) For the covering entry of this conference, please see ITRD abstract no. E204495.
23rd Annual International Conference on Composites or Nano Engineering (ICCE23), 2015
This paper presents a summary of preliminary results obtained from an experimental investigation ... more This paper presents a summary of preliminary results obtained from an experimental investigation on the behavior of web-flange junctions of pultruded glass fibre-reinforced polymer (GFRP) I-profiles. In particular, the aim of the study is to suggest simple stiffening and strengthening element to improve the axial flexibility and strength of the junctions. Digital image correlation technique was used to capture in plane displacements and strains of the specimens
This paper presents results of an experimental study that focuses on monitoring changes in dynami... more This paper presents results of an experimental study that focuses on monitoring changes in dynamic characteristics of a damaged and retrofitted two-story reinforced concrete (RC) building model with poor detailing. In the study, ambient vibration tests are performed via four test setup protocols in order to monitor changes in dynamic characteristics before and after such setups. The four main test setups are: (i) undamaged (as-built) case (Setup # 1), (ii) damaged cases with different degrees of damages (Setup # 2), (iii) repaired case with different types of repair methods (Setup # 3), and (iv) strengthened case with externally bonded CFRP composite laminates (Setup # 4). In addition, a total of eight ambient vibration tests are conducted in order to assess the effects of degree of damage and associated retrofit systems on building’s dynamic characteristics such as natural frequencies, mode shapes, and damping ratios. The Stochastic Subspace Identification (SSI) Method is used to identify the dynamic characteristics. Experimentally identified dynamic characteristics obtained from all setups are compared with each other in order to detect the effect of damage and repair applications on the structure’s dynamic characteristics. Moreover, Modal Assurance Criterion (MAC) and Coordinate Modal Assurance Criterion (COMAC) are determined to examine the changes of stiffness of each RC building model.
Abstract The use of an innovative type of perfobond rib (PBL) shear connector in steel–concrete j... more Abstract The use of an innovative type of perfobond rib (PBL) shear connector in steel–concrete joints of hybrid girder bridges has gained wide popularity among bridge engineers. For a PBL group with multi-row PBLs in tandem arrays, comprehensive interactions exist among the connectors. However, the current design approaches assume that the force transferred by each row of PBL is uniform, resulting in an overestimated shear resistance of the connector group. The main objective of this paper is to introduce a mathematical approach, which accounts for the bonding-friction effects (BF) at the perforated steel plate/concrete slab interfaces and the reinforced concrete dowel (RD) effects by the perfobond hole, to assess the ultimate resistance of PBL group under the RD fracture failure mode. In this study, six push-out specimens for different PBL groups, with varying connectors’ quantity, were evaluated experimentally to determine the key parameters for the proposed analytical model. The experimental results revealed the significant reduction in average resistance of single PBL in a connector group as connector number increased. The proposed approach is validated by an experimental database that includes push-out test results obtained from the previously published studies and afterwards converted to the design load level, which can be extensively applied to the PBL group using normal concrete and ultra-high performance concrete (UHPC). The proposed analytical approach provides an efficient tool for analyzing and designing of PBL group in steel–concrete joints of hybrid girder bridges.
Uploads
Papers by Ayman S MOSALLAM