International Concrete Abstracts Portal

This volume contains 72 papers from the 10th International Symposium held in Tampa, FL. The papers address internally reinforced members, strengthening of columns, material characterization, bond, emerging fiber-reinforced polymer (FRP) systems, shear strengthening, fatigue and anchorage systems, masonry, extreme events, applications, durability, and strengthening. The papers emphasize the experimental, analytical, and numerical validations of using FRP composites and are aimed at providing insights needed for improving existing guidelines. The increasing maturity and acceptance of FRP is reflected by several papers that provide background information on the recent design codes and guidelines relating to blast and seismic repair. New frontiers of FRP research are explored, addressing emergin materials, and systems and applications for extreme events, such as fires and earthquakes, which will further consolidate FRP’s preeminent position. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-275

The structural reliability of concrete flexural members reinforced with fiber reinforced polymer (FRP) reinforcement is investigated. Reliability indices based on the equations for flexure in ACI 440.1R-03, which uses the load factors from ACI 318-99 are presented. Choice of a resistance factor for flexure for ACI 440.1R-06, which uses the load factors from ACI 318-02 is also presented. Flexural designs using either ACI 440.1R-03 or ACI 440.1R-06 provide sufficient reliability, with reliability indices between 3.5 and 4.8, with the older versions of ACI 440.1R yielding higher reliability. An analysis of curvature of the beams at failure showed that flexural members that fail by FRP reinforcement rupture have ductilities similar to those that fail by concrete crushing, indicating that FRP reinforcement fracture is not necessarily a more brittle failure mode than concrete crushing.

A large part of tuff buildings in the Mediterranean area is of historical and artistic relevance. Such buildings are placed in seismic areas and, due to their age, have been subjected to environmental deterioration. For this reason, in the last decades, the interest in strengthening of historical tuff masonry structures is significantly grown especially to techniques that allow properties like as reversibility, compatibility, and sustainability of the intervention to be combined. In the present paper, the results of diagonal compression tests on yellow tuff masonry panels is presented; the specimens were reinforced by using an innovative strengthening system based on the combined use of a pre-cured alkali-resistant basalt or glass FRP grid bonded with a cement based mortar or pre-mixed high ductility hydraulic lime and pozzolan based mortar. Base material properties as well as panels in-plane deformation and strength, including the post peak softening regime in view of seismic applications, are reported in the paper. The experimental results confirmed the effectiveness of the investigated strengthening technique to increase the tuff panels shear strength and validated the use of an innovative mortar specifically formulated to increase the compatibility with tuff material and historical grouting.

This paper describes a simplified methodology to design masonry and concrete walls retrofitted with fiber-reinforced polymer (FRP) products to resist blast load. The wall is analyzed as an equivalent single-degree-of-freedom (SDOF) system responding in flexure to a spatially uniform blast load. The methodology provides specific guidance on how to define all the relevant properties of the equivalent SDOF system based on flexural and shear properties of the retrofitted wall using equations similar to those for static properties of retrofitted walls in ACI 440.2R responding in flexure. The methodology also provides response limits that give correlations between the calculated maximum dynamic response and the corresponding blast damage level to the retrofitted wall. The response limits can be used to design a blast resistant wall for a given amount of acceptable damage. This paper discusses the SDOF-based procedure, summarizes available blast test data on retrofitted walls, and shows comparisons between maximum deflections calculated with equivalent SDOF models of the test walls and measured values. Also, the development of the response limits is described with photographs of observed wall damage levels in shock tube tests.

Carbon Fibre reinforced Polymers (CFRP) have become an effective solution to upgrade and strengthen existing box girder bridges in flexure, shear and torsion. The introduction of CFRP strain limitations to prevent premature delamination together with the increasing strengthening demands and the necessity for use of fibres of increasing stiffness and thickness has resulted in a very poor CFRP material utilisation levels achieved in practice. An effective method to increase CFRP material utilisation is by appropriately anchoring the ends of the CFRP. In this paper, a study into CFRP end anchorage solutions is presented which formed the basis of the experimental program. Both uni-directional and bi-directional fabric was applied to the ends of CFRP laminates and tested under direct shear loading. Uni-directional fabric was oriented both horizontally across and parallel to the direction of the laminate. In all cases it was found that the anchorages solutions tested resulted in a distribution of fibre-to-adhesive bond stresses over a greater length, width of concrete and could potentially result full CFRP utilisation and laminate rupture.