Test and Finite Element Analysis of Gravity Load Designed Precast Concrete Wall Under Reversed Cyclic Loads

This research studies the lateral behavior of precast concrete wall panel applicable for a 2-story building. The specimens consist of precast and cast in-situ reinforced concrete bearing wall with 3/4 scaled. The precast wall panel was designed for gravity load only. The specific connection in this study was the welded connection between dowel bar and steel plate embedded in precast wall which was the famous one of the connection for precast bearing wall system in Thailand. The specimens are tested under reversed cyclic loadings through hydraulic actuator in laboratory. The tested results reveal that the precast concrete wall can resist maximum lateral load and show almost the same behavior as cast in-situ RC wall. The cracks of precast wall panel are concentrated around the connection while cast in-situ RC wall are flexural and shear cracks dominant 500 millimeters above the footing of wall. The superimposed technique of the element in FEM analysis is used to model the connection of precast wall. The prediction by FEM analysis for cyclic behavior, hysteretic loop and maximum load are matched with the test results for both specimens

Uncertainty and Fuzzy Decisions in Earthquake Risk Evaluation of Buildings

The Northern region of Thailand has been considered as one of the seismic risk zones. However, most existing buildings in the area had been designed and constructed based on old building design codes without seismic consideration. Therefore, those buildings are required to upgrade based on earthquake building damage risk evaluation. With resource limitations, it is not feasible to retrofit all buildings in a short period. In addition, the results of the risk evaluation contain uncertain inputs and outputs. The objective of this study is to prioritize building retrofit based on fuzzy earthquake risk assessment. The risk assessment of a building was made considering the risk factors including (1) building vulnerability, (2) seismic intensity and (3) building values. Then, the total risk was calculated by integrating all the risk factors with their uncertainties using a fuzzy rule based model. An example of the retrofit prioritization is shown here considering the three fuzzy factors. The ranking is hospital, temple, school, government building, factory and house, respectively. The result helps decision makers to screen and prioritize the building retrofitting in the seismically prone area

Analisis Anteseden Orientasi Pasar Dan Pengaruhnya Terhadap Pembelajaran Organisasi UMKM Di Eks Karesidenan Surakarta

The weakness of leaders in Small and Medium Business (UKM) in Indonesia dealing with market oriented are the low motivation of entrepreneurs, the low of leader commitment to apply market orientedmethod in his organization, and lack of training for themselves (Suliyanto, 2011). This research aimed to develop the culture of market oriented throughout the learning of organization that be done by examining the effect of customers and competitorsoriented to the learning of organization. Respondents of this research are 300 owners or managers of UKM in the Greater of Surakarta. The technique of sampling in this research is purposive sample who has two criteria; an Indonesian and at least has two employees. The technique of analysis was done by Structural Equation Model (SEM). The result of this research shows antecedent variable; entrepreneurs\u27 orientation, under-pressured of managers, training programs, and reward system has effect to customer orientation in Small and Medium Business (UKM)

Residual Strength of Reinforced Concrete Beams under Sequential Small Impact Loads

Abstract: Sequential small impact loads may not collapse structures directly but could weaken the strength of structures. This study aimed to investigate the impact of these sequential small impactloads on the strength of the reinforced concrete beams. First, six sequential impact loads were applied to the test specimens. Then, the residual static capacity of the impacted specimens was determinedby the ultimate static load test, compared with those of undamaged specimens. The experiment was composed of 12 specimens having identical dimensions. The variable parameters were the magnitude of the axial load and shear reinforcement. Under the sequential small impacts, the axial load improves the impact performance. It reduces the tensile strain of the longitudinal reinforcement. Hence, the flexural tensile crack propagation is limited. In addition, the local damage at the impact location is minimized and the shear plug induced diagonal shear crack is prevented. The axial force is also able to diminish the adverse effect of the large spacing stirrups. Large impact load could alter the failure of a designed flexural critical reinforced concrete beam without axial load to the shear failure. Although the axial load improves the impact response, the Residual Resistance Index (RRI) decreases with axial load. For the damaged specimens with axial load, the ultimate static load is lower than the calculated concrete shear capacity and more severe diagonal shear cracks were found. It can be obviously said that the prior impact damage decreases the concrete shear capacity

A model for the simultaneous prediction of the flexural and shear deflections of statically determinate and indeterminate RC structures

The deformability of the major part of reinforced concrete (RC) structures is the result of the flexural and shear deformations mainly caused by bending and shear diagonal cracking, respectively. However, the evaluation of the shear deformation contribution is relatively difficult due to the complexities involving the shear behavior of cracked RC elements. These complexities are even more complicated when structures are statically indeterminate, since the external and internal forces cannot be determined from direct application of the equilibrium equations. To address these issues, the current study aims to develop a novel simplified analytical model based on the flexibility (force) method to predict the deflections of statically indeterminate RC structures up to their failure, which can be in bending or in shear. This analytical model considers the influence of flexural cracks on the shear stiffness degradation of a RC structure after concrete cracking initiation, and has a format adjusted for design practice. The good predictive performance of the analytical model is demonstrated by simulating experimental tests with RC elements where shear deformation has different level of contribution for the total deflection registered in these tests.Marie Curie Initial Training Networks - "endure" European Network for Durable Reinforcement and Rehabilitation Solutions, project no: 607851.info:eu-repo/semantics/publishedVersio

Nonlinear response of RC columns subjected to equal energy-double impact loads

Defining the damage and deflection from the impact by using only the impact energy could be misleading due to the effect of the impact momentum. In addition, reinforced concrete columns might be subjected to repeated impact loading. Hence, this study presents the numerical simula-tion of 16 RC columns with identical sizing and reinforcement details, subjected to equal ener-gy-double impact loadings using a free-falling mass at midspan. The impact energy was kept constant for both impacts. For each analysis, the impact momentum was varied by varying the velocity and mass of the impactor. The axial load ratios of the columns are between 0.0 to 0.3 of the compressive strength of the concrete cross-section. The results clearly addressed the momentum effect on the impact responses. The momentum level affected the specimens' damage behavior under the same input impact energy. A high momentum impact yielded more global flexural damage with large deflection, and a low momentum impact produced more local damage with a slight deflection. The axial load helps maintain the impact resistance capacity. However, the failure determined by the flexural damage pattern under the first impact was changed when subjected to the second impact to the shear mode with the presence of axial load. Further, the colliding index considering the momentum was used in the deflection prediction equation. The proposed equation improved the deflection calculation accuracy of reinforced concrete beams under equal-energy but different momentum impact

Eco-friendly 3D Printing Mortar with Low Cement Content: Investigation on Printability and Mechanical Properties

The conventional approach to achieving optimal printability and buildability in 3D printing mortar relies heavily on cement, which is both costly and environmentally detrimental due to substantial carbon emissions from its production. This study aims to mitigate these issues by investigating the viability of slag as a partial substitute for cement, with the goal of developing an eco-friendly alternative. The newly formulated mortar, featuring a 30% reduction in cement content (from 830 to 581 kg/m3) and the inclusion of 0.10% micro-fibers, exhibits properties comparable to conventional 3D printing mortar. The research is structured into two parts: Part 1 focuses on determining the optimal fiber content, while Part 2 delves into the investigation of fiber-reinforced mortar with reduced cement content for 3D printing. Criteria were established to ensure mortar flow at 115%, initial printable time below 60 minutes, and 7-day compressive strength exceeding 28 MPa. Part 1 results indicate that a fiber content of 0.1% by volume meets the specified requirements. In Part 2, it was observed that increasing the slag replacement percentage extended the initial printable time and time gap. However, even at a 30% replacement rate, the initial printable time remained within the acceptable range, partially attributed to the presence of fibers in the mix. Additionally, higher slag content led to increased flow and reduced filament height in the mixes. Notably, all formulations surpassed the 7-day compressive strength threshold. These findings underscore the potential of slag as a sustainable alternative to cement in 3D printing fiber-reinforced mortar, offering promising prospects for environmentally friendly construction practices

Experimental and analytical investigation on flexural behaviour of RC beams strengthened with NSM CFRP prestressed concrete prisms

This investigation aims to study the flexural behaviour of reinforced concrete (RC) beams strengthened with near-surface mounted (NSM) carbon fibre reinforced polymer prestressed concrete prisms (CFRP-PCPs). Eight RC beams were tested under monotonic loading until the failure load was reached. One beam was un-strengthened to act as a control beam. The other seven beams were strengthened with non-prestressed or prestressed NSM CFRP-PCPs. The effects of bond length, prestress level, and concrete type of the CFRP-PCPs on the flexural capacity, flexural crack and deflection are discussed in this paper. The results indicate that the flexural capacity of RC beams strengthened with NSM CFRP-PCPs was greater than the control beam. An obvious improvement was discovered in the crack resistance when the RC beams were strengthened with prestressed NSM CFRP-PCPs. The strengthened beams showed a higher first-cracking, yielding, and ultimate load as the bond length and prestress level of CFRP-PCPs increased up to a critical level. The beams strengthened with CFRP-PCPs, which were cast with ultra-high performance concrete (UHPC), exhibited greater load capacity than the corresponding beams with epoxy resin mortar. The analytical model of flexural response for the NSM CFRP-PCPs strengthening beams is presented. The analytical results are in good agreement with the experimental results, which revealed the NSM CFRP-PCPs is an effective technique for flexural strengthening of the RC beams

Characteristic and Allowable Compressive Strengths of Dendrocalamus Sericeus Bamboo Culms with/without Node Using Artificial Neural Networks

The strength of construction material is a crucial consideration in the process of structural design and construction. Conventional materials such as concrete or steel have been widely utilized due to their predictable material performance. However, a significant obstacle to the widespread use of bamboo in structural elements lies in the challenge of its standardization. Many previous research studies have explored bamboo’s load bearing capacity, but the information remains limited due to variations in species, size, age, physical properties, moisture content, and other factors, making it difficult to predict their load-bearing capacity. This study aims to propose Artificial Neural Network (ANN) models to predict ultimate compressive load and compressive strength of Dendrocalamus Sericeus bamboo culm. Additionally, for structural design purposes, the proposed ANN models were employed to determine the characteristic and allowable compressive strengths. As a first step, experimental data from compressive tests in the literature were used for training and developing the ANN model. To investigate the effect of the node on compressive loading capacities, the test data were separated into two datasets, “Node” samples and “Internode” samples. Through the training process, ANN models were finally proposed, and the R-square values for the prediction of ultimate compressive load and compressive strength from the proposed ANN models were significantly higher than those obtained from the linear regression analyses used in the literature. Subsequently, the characteristic and allowable compressive strengths were calculated and compared to the strengths obtained from the experiment data, revealing a difference of approximately only 8.0%. Overall, the ANN models presented in this study offer promising predictive ability for both ultimate compressive load and compressive strength of Dendrocalamus Sericeus bamboo culm, as well as for determining characteristic and allowable strengths. Hence, ANN models are suggested to be adopted as a tool for the design and construction of bamboo buildings

Experimental and Analytical Studies on Steel-Reinforced Concrete Composite Members with Bonded Prestressed CFRP tendon under Eccentric Tension

This paper reported the very earliest experimental and analytical studies on the bonded Prestressed CFRP tendon enhanced Steel Reinforced Concrete (PSRC) members under eccentric tensile loads. Eight PSRC members were tested under monotonic eccentric tensile loading, and three Steel Reinforced Concrete (SRC) members were simultaneously tested for comparison. The load-deflection relationship, the strain distributions as well as the crack propagation and fracture of concrete were investigated experimentally and analytically. The results demonstrated an improvement in the eccentric tensile capacity of PSRC members upon increasing both the steel and reinforcement ratios, or by reducing the prestress eccentricity. The results also suggested that an enhancement in the level of prestressing increased can decrease the crack propagation and lateral deflection. Moreover, the validity of the plane-section assumption was confirmed. An analytical model was proposed for predicting the elastic bending capacity of the PSRC members based on the experimental results. The study provided an in-depth understanding of the structural behaviour of PSRC members with bonded prestressed CFRP tendon under the eccentric tension underpinned by the elaborate experimental design and practical analytical model