Title:
Assessment of Anchorage Methods and FRP Laminate Strengthening Configurations for URM Walls Under In-Plane Loading
Author(s):
Nancy Torres, Gustavo Tumialan, and Camilo Vega
Publication:
Symposium Paper
Volume:
327
Issue:
Appears on pages(s):
12.1-12.20
Keywords:
unreinforced masonry walls; strengthening, in-plane behavior; anchorage, FRP laminates
DOI:
10.14359/51713333
Date:
11/1/2018
Abstract:
In order to ensure a continuous and reliable path for the lateral loads caused by earthquake or wind
forces, FRP-strengthened masonry walls that are part of the lateral load resisting system of a building require the
joint work of the FRP strengthening to resist tensile stresses in the masonry and anchorage to the boundary structural
elements (foundations or beams) to transfer the loads. This article presents the results of an investigation on the
assessment of anchorage methods and FRP strengthening configurations for unreinforced masonry (URM) walls
subjected to in-plane loads. Fourteen masonry walls were constructed for this experimental program. All of the walls
were built with hollow clay bricks, typical of URM structures in Colombia and other parts of the world. The
specimens for this investigation included slender and squat walls. The dimensions of the slender walls were 1.20 m.
[4 ft] long, 1.90 m. [6.2 ft.] high, and 120 mm [4.8 in.] thick. The dimensions of the squat walls: 2.50 m. [8.2 ft.]
long, 1.90 m. [6.2 ft.] high, and 120 mm [4.8 in.] thick. The walls were strengthened using two configurations: (1)
Layout ‘H’ involving horizontal CFRP laminates along on wall side, and vertical CFRP laminates at each wall toe
on one side of the wall, and (20 Layout ‘X’ involving diagonal CFRP laminates oriented at approximately 45
degrees on one side of the wall. Four anchor systems were evaluated: (1) System 1 (CFRP anchors embedded in the
base beam), (2) System 2 (CFRP bonded to the base beam), (3) System 3 (FRP bonded to grout blocks), and (4)
System 4 (FRP wrapped around grout blocks). The walls were tested in two series: (1) Series 1 – Monotonic
Loading, and (2) Series 2 – Cyclic Loading. The test results demonstrated that Anchor System 4 was the most
effective anchorage system. The walls strengthened with Anchor System 4 failed due to rupture of the CFRP
laminates wrapped around the grout block. In general, the largest increases in in-plane capacity, when compared to
the control walls, were observed in the slender walls. The walls with the ‘H’ Layout showed more ductility and less
degradation of the lateral stiffness than the walls strengthened with the ‘X’ Layout.