Date of Publication

3-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Subject Categories

Civil Engineering

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Thesis Advisor

Jason Maximino C. Ongpeng
Julius L. Leaño, Jr.

Defense Panel Chair

Bernardo A. Lejano

Defense Panel Member

Andres Winston C. Oreta
Michael Angelo B. Promentilla
Lessandro Estelito O. Garciano
Ernesto J. Guades

Abstract/Summary

Old structures such as historic churches, old school buildings, and arches are often constructed with unreinforced masonry walls (URM), which typically consist of adobe or brick walls. The design of most URM is for gravity loads only and not intended to resist lateral forces induced by seismic activities. Most URM walls fail under in-plane shear. The main objective of this study is to provide an acceptable externally bonded strengthening method for URM brick walls. To maximize the impact of the study in preserving lives, environmentally friendly materials such as mill-scale (MS) waste, flyash (FA), and bamboo fibers (BF), were used to develop the strengthening system. MS powder was used to partially replace FA in geopolymer-making with optimum 1:5 MSto- FA ratio. BF extracted using 5% sodium hydroxide solution from Kawayan Tinik, and treated with additional 10% aluminum sulfate solution, were used as short fiber reinforcement and as BF geotextile to reinforce the MS-FA based geopolymer mortar that is used as the plastering for the strengthening system. Wallette size specimens, 350 mm x 350 mm, were subjected to diagonal shear tests in accordance with modified ASTM E519 guidelines. By strengthening the wallettes on both faces with the geotextile reinforced geopolymer system, their shear capacity improved, resulting in an average increase of 55.78% in the amount of shear force the wallettes can resist. The wallettes that were strengthened on one side only also improved with an average increase of 33.20% in average shear force resisted. The deformability of the wallettes, expressed as pseudo-ductility ratio, improved up to 1.55 ratio compared to 1.04 ratio of the control samples. This suggests that the specimen underwent additional deformation after the initial cracking, indicating that the strengthening method contributes in improving the overall shear performance of the strengthened URM wallette. The resulting modulus of rigidity of each strengthening method and tensile strength of BF textile were used as base values for ACI 549.4R analytical models to compute the nominal shear capacity of the wallettes. The computed nominal shear capacities present the shear contributions of the URM and of the proposed strengthening method.

Abstract Format

html

Language

English

Keywords

Bamboo; Inorganic polymers; Fiber-reinforced concrete; Bricks—Fatigue; Adobe brick—Fatigue

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5-4-2025

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