Ancient Materials and Substitution Materials Used in Thai Historical Masonry Structure Preservation

The historical structures of Thailand are some of the most fascinating ancient sites in Asia.Their architectures reveal past cultures,traditions,knowledge,and expertise.Masonry materials are the major materials used to construct the historical structures in Thailand.One of the essential problem of Thai historical structure preservation is a shortage of engineering properties data for the structural stability assessment.Moreover,the in-depth engineering properties and the suitable substitution materials for Thai historical preservation are rarely found.Therefore,the engineering properties of the ancient masonry materials have to be explored together with the development of suitable substitute materials.This paper presents the physical and engineering properties of ancient materials and substitution materials for the preservation of Thailand’s historical structures.The ancient materials,including brick and mortar,are collected from historical places in the Bangkok and Ayutthaya Provinces.The physical and engineering properties of the masonry materials,such as the chemical composition,mineralogical composition,density,porosity,absorption,water vapor transmission,compressive strength,and modulus of elasticity,were evaluated in the laboratory.Fly ash was used as a pozzolanic material to partially replace the slaked lime to restore the historical mortar.The binder to sand ratio was controlled at 1:3 by weight.The slaked lime was substituted by fly ash at the rates of 10–30%by weight of binder.The engineering properties of the substitution mortars were also evaluated and compared with the ancient masonry materials.A masonry prism was also constructed to evaluate the compressive strength and the modulus of elasticity of the masonry structures.The physical and engineering properties of the ancient masonry materials obtained in this study can be included in a database for the preservation of Thailand’s historical masonry structures.The use of fly ash to partially replace the slaked lime could decrease the setting time and increase the compressive strength of historical repair mortar.The empirical equation obtained from this study could be used to predict the compressive strength of the masonry prisms of Thailand’s historical structures.

Performance evaluation of low-rise infilled reinforced concrete frames designed by considering local effects on column shear demand

The interactions between reinforced concrete(RC)frames and infill walls play an important role in the seismic response of frames,particularly for low-rise frames.Infill walls can increase the overall lateral strength and stiffness of the frame owing to their high strength and stiffness.However,local wall-frame interactions can also lead to increased shear demand in the columns owing to the compressive diagonal strut force from the infill wall,which can result in failure or in serious situations,collapse.In this study,the effectiveness of a design strategy to consider the complex infill wall interaction was investigated.The approach was used to design example RC frames with infill walls in locations with different seismicity levels in Thailand.The performance of these frames was assessed using nonlinear static,and dynamic analyses.The performance of the frames and the failure modes were compared with those of frames designed without considering the infill wall or the local interactions.It was found that even though the overall responses of the buildings designed with and without consideration of the local interaction of the infill walls were similar in terms the overall lateral strength,the failure modes were different.The proposed method can eliminate the column shear failure from the building.Finally,the merits and limitations of this approach are discussed and summarized.