PERFORMANCE OF HIGH STRENGTH LIGHTWEIGHT CONCRETE USING PALM WASTES

The performance of high strength structural lightweight concrete (LWC) using the palm wastes, oil palm shell (OPS) as well as palm oil clinker (POC) has been reported. Existing literatures used either OPS or POC individually for production of LWC. Each concept has their own advantages-disadvantages. In this study, both OPS and POC have been put together as coarse aggregate on the way to see the improvement of mechanical properties of waste based LWC. To achieve this purpose, regular coarse aggregate has been fully replaced by OPS and POC in the concrete. This structural grade lightweight concrete is named as palm shell and clinker concrete (PSCC). Attempts have been made with the series of OPS and POC mixture aimed at identifying for better performance. The quantity of OPS and POC mix has been varied as 30%, 40%, 50%, 60% and 70%. Mechanical properties of PSCC like density, workability, compressive strength at different ages, flexural strength, splitting tensile strength as well as modulus of elasticity have been evaluated. It is revealed that the proposed PSCC has extensive potential in terms of high compressive strength and good material behavior to perform as a better LWC. The study could offer structural lightweight concrete of compressive strength up to 46 MPa that is 31% higher than the control mix. The usage of 50% OPS to 50% POC coarse aggregate by vol. in the concrete mix is found to be the optimum mix. Furthermore, simple correlations have been developed which can easily predict compressive strength, splitting tensile strength, flexural strength, modulus of elasticity and ultrasonic pulse velocity of lightweight concrete

Parameters estimation of Drucker-Prager plasticity criteria for steel confined circular concrete columns in compression

This paper explores the possibility to use Drucker-Prager model in Steel-Concrete composite section. Numerical simulation was conducted using finite element package to simulate the steel-concrete composite section subjected to uniaxial compressive loading. After calibration with experimental study, parametric study was conducted to evaluate the effect of the friction angle and the cohesion constant c on the stress-strain curve of composite section. Empirical relationship between the friction angle and the confined concrete compressive strength was developed and a range of cohesion constant c between 5-10 MPa was suggested for confined concrete strength range of 25 to 100 MPa, respectively

Potential Design of Seismic Vulnerable Buildings Incorporating Lead Rubber Bearing

The seismic hazard of vulnerable regions warrants the investigation of new technologies, such as base level isolation by lead rubber bearing (LRB) devices, that can help to mitigate structural damage on seismic prone buildings. The behavior adopting such technologies can be dynamically observed in simulated environments and thus serves as a valuable metric for their feasibility. LRB base isolators were incorporated into the design of 16 model buildings to better understand how they affected a building’s seismic response while also providing information on the structural parameters. A total of 12 different types of bearing systems were tested in base isolated (BI) buildings against conventional fixed-base (FB) isolated buildings. The system of each model high-rise building was represented by the finite element package. Static as well as dynamic analysis were conducted using response spectrum analysis (RSA) based on the seismic excitation to determine the influence of the model type in the aseismic design and the alteration in superstructure behavior. The study reveals that the LRB isolators can potentially diminish respective story accelerations, story inertia, and base shear. Use of LRB isolators in BI buildings resulted in a 10⁻20% reduction in base shear compared to FB buildings. A notable lateral shift of superstructure is offered by LRB-induced flexibility. The reduction of story acceleration for response spectrum varies 30% on lower stories up to 70% on upper stories. The LRB systems with higher characteristic strength and relatively less isolation periods shows better productivity to minimize displacements in the bearing face for dropping structural shift. However, the LRB with comparatively lower characteristic strength and high isolation periods shows the most efficiency in controlling base shear, offering least story accelerations and consenting lower story inertia forces