The majority of studies on fiber-reinforced-polymer (FRP) strengthened concrete columns deal with columns of a circular cross section. However, most concrete columns in the field have square or rectangular cross sections and resist eccentric loads. This paper presents the results of an experimental study on the performance of carbon-fiber-reinforced-polymer (CFRP) wrapped square reinforced concrete (RC) columns under eccentric loading. The influence of the number of CFRP layers, the magnitude of eccentricity, and the presence of vertical CFRP straps were investigated by testing 16 specimens. The specimens had the dimensions 200 × 200 × 800 mm and round corners with a radius of 34 mm. Twelve specimens were tested as columns and four specimens as beams. The results of this study showed that CFRP wrapping enhanced the load-carrying capacity and ductility of the columns under eccentric loading. Furthermore, the application of the vertical CFRP straps significantly improved the performance of the columns with large eccentricity Abstract: The majority of studies on fiber-reinforced-polymer (FRP) strengthened concrete columns deal with columns of a circular cross section. However, most concrete columns in the field have square or rectangular cross sections and resist eccentric loads. This paper presents the results of an experimental study on the performance of carbon-fiber-reinforced-polymer (CFRP) wrapped square reinforced concrete (RC) columns under eccentric loading. The influence of the number of CFRP layers, the magnitude of eccentricity, and the presence of vertical CFRP straps were investigated by testing 16 specimens. The specimens had the dimensions 200 × 200 × 800 mm and round corners with a radius of 34 mm. Twelve specimens were tested as columns and four specimens as beams. The results of this study showed that CFRP wrapping enhanced the load-carrying capacity and ductility of the columns under eccentric loading. Furthermore, the application of the vertical CFRP straps significantly improved the performance of the columns with large eccentricity.

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The paper presents analysis results of structural behaviour with and without soil-structure interaction on a five-story reinforced concrete building with basements due to seismic loads. Two numbers of basements were considered namely the building with one basement floor (M1 model) and two basement floors (M2 model). Each of the M1 and M2 model has three variations with and without the soil structure interaction namely the model with the fixed supports (MJ1 and MJ2 models), the model with solid element of the soil (MSo1 and MSo2 models), and the model with lateral soil support of spring elements (MSp1 and MSp2 models). The Soil parameters of modulus elasticity, poisons ratio, reaction modulus and spring stiffness for the MSo and MSp models were obtained from soil investigation. All six models having loads combination of gravity and earthquake loads were analysed using a finite element software package program. All loadings and design codes follow Indonesian codes. Earthquake loads were evaluated using two methods namely equivalent static loads and spectrum response analysis. The results show that the roof-floor displacements of the soil-structure interaction model (MSo and MSp) are greater 2% to 3% than to that of the non-soil-structure interaction models (MJ). The roof drift and natural fundamental period of the MSo and MSp models is greater 1% to 2% than that of the MJ model. The axial force of the columns in the MSo and MSp models is less 1% to 3% than the MJ model. The addition of basement floors to the building and modelling with soil structure interactions can minimize the roof floor displacement, the natural fundamental period of the structure, and axial force of the column by 1% to 2%.

This research focuses on the mechanical and microstructure properties of geopolymer binder with slatestone waste as the base material. This geopolymer binder comes from industrial waste crushing slate in the Umeanyar area. This waste is processed into stone powder (USSP) which contains SiO 2 (49%), Al 2 O3 (11%), CaO (11.2%). This USSP uses a sodium hydroxide (SS) activator with a concentration of 14 M. The proportion of the mixture of precursor and activator (P/A) is 70%: 30%; 75%: 25%; 80%: 20% and alkaline activator Na 2 SiO 3 : NaOH (SS/SH) of 1:1; 1.5:1; 2:1, by weight. Samples of specimens were made in the form of a cube with a side of 50 mm and tested at the age of 7 and 28 days. Mechanical properties tested include density and compressive strength based on ASTM-C39. Meanwhile, the microstructural analysis used X-Ray Diffraction (XRD) and Scanning Electronic Microscope-Energy Dispersive X-Ray (SEM-EDX) analysis. The results of the density test were 1.90g/cm 3 and 1.85g/cm 3 respectively and the compressive strength test results were 7.40 MPa and 12.73 MPa at the age of 7 and 28 days, respectively.