Composite slab numerical strength test method under M-K approach

The paper presents an experimental validation of proposed numerical strength determination function for profiled deck composite slab (PDCS). The study is timely in finding solution to the costlier and mandatory laboratory procedure required for the strength determination for PDCS. The study load carrying capacity is from the longitudinal shear capacity estimation using slope-intercept method. The study yields to the formation of numerical load determination function for PDCS and the validation test programme consisted of four shear span length under unrestrained conditions. The litmus test comparisons of load capacity with the experimental test result shows good prospect of the numerical load model in determining the strength capacity of PDCS. Index Terms- Composite slab, Failure test load, Longitudinal shear, Slope-intercept method

Profiled composite slab strength determination method

The purpose of this article is to develop a new numerical approach for determining the strength capacity of a profiled composite slab (PCS) devoid of the current challenges of expensive and complex laboratory procedure required for establishing its longitudinal shear capacity. The new Failure Test Load (FTL) methodology is from a reliability-based evaluation of PCS load capacity design with longitudinal shear estimation under slope-intercept (m-k) method. The limit-state capacity development is through consideration of the experimental FTL value as the maximum material strength, and design load equivalent estimation using the shear capacity computation. This facilitates the complex strength verification of PDCS in a more simplified form that is capable of predicting FTL value, which will aid in determining the longitudinal shear of profiled deck composite slab with ease. The developed strength determination effectively performs well in mimicking the probabilistic deck performance and composite slab strength determination. The strength test performance between the developed scheme and the experiment-based test results indicates high similarity, demonstrating the viability of the proposed strength determination methodology

Composite slab strength determination approach through reliability analysis

The economic use and ease of construction of profiled deck composite slabs faces the challenge of complex and costly strength determination procedures. This is through the longitudinal shear strength determination that shows the level of composite action between the decking sheet and concrete, and a number of methods are available for its determination; the partial shear method is one such method. The Eurocode design provision requires experimental procedures in establishing the shear strength parameter. However, the cost and time constraint associated with the strength verification is a critical issue of major concern that is currently receiving attention. This study proposes to address these challenges by implementing a rational based approach in developing a numerical function for profiled composite slab strength devoid of experimental procedure. The developed methodology is from reliability-based analyses of longitudinal shear load carrying capacity of profiled deck composite slab from partial shear connection method to Eurocode provision. The proposed methodology results indicate good agreement with the performance of full-scale experimental tests

Effect of tropical climate to compressive strength of high performance fibre reinforced concrete

High performance fibre reinforced concrete (HPFRC) is relatively an advance fibre reinforced concrete (FRC) material, which is made of more than 2% volume fraction of fibres. This research focuses on the effect of tropical climate on the compressive strength of HPFRC. Total of 56 HPFRC cubes made of 3%, 4% and 5% of hooked-end fibres and grade 80 slurry were prepared. Half of which were exposed to tropical climate condition (80% humidity at 35°C) for 30 days which the other half are placed in room temperature. After which, the compression test was carried out. The highest compressive strength of 152.2 MPa was recorded from samples made of 5% fibre volume and being exposed to tropical climate, which is 90% higher than the control sample

Continuous RC slab flexural limit state optimization from slab depth consideration

The use of reliability based structural optimisation is a rational approach that can accounts for the inherents uncertainities associated with the design varaibles. Despite the availability of this powerful tool its application on real life structures remains a crtitical issue amongst practicing engineers, principally due to high numerical cost involved in finding solutions using this method. Studies have shown, the few available literatures are mostly on steel structures, and very few covers concrete structures, specifically RC slab. In order to bridge this cavity, this paper present a non-conventional slab depth optimisation for the design of continuous RC slab types. The study seeks to know the effect of reducing the current minimum design depth applicable for two-way slab confirming to standard fire resistance requirement, REI240 on flexural capacity requirement along both axes with the use of first order reliability method. The study was limited to four different rectangualr slab ends condition. The study safety analysis results in comparison with weighted least square and objective cost functions evaluation shows good prospect in terms of cost saving and yet avoiding flexural failure through the application of the aforementioned rational method

Finite element analysis of proposed self-locking joint for modular steel structures

The intermodular connection between modules plays a vital role in the overall performance of modular structures. The separation between a column and connection is possible due to the absence of links (welding or bolting) since limited space is available between modules. This study proposed a self-locking joint to be used in a modular steel structure, connecting columns with a connection without need of extra space between modules. The behavior of the proposed connection subjected to monotonic load was evaluated using a finite element approach using ABAQUS software. The influencing factors contributed to the behavior of the self-locking connection and columns observed using a parametric study. The parametric study was conducted by varying beam thickness, bolt pretension force and friction coefficient µ. Results indicate that the proposed connection can be classified as a semirigid connection according to Eurocode 3 and special moment frame (SMF) as recommended by AISC

Numerical and experimental evaluation of a developed nonlinear curved spring element under compression force

AbstractThis paper presents an evaluation of a curved spring element that may be utilized in a developed variable stiffness bracing (VSB) system to confer the variable stiffness characteristic of the system.VSB system is established to protect the structure against dynamic loads induced by earthquake, wind and etc. To obtain the curved shape of the spring, mathematical modeling is conducted. Direct compression experimental tests are conducted for a variety of models with different thicknesses and materials. The results of the experiments show a nonlinear stiffness trend for the curved spring element. In addition, to observe the yielding of the curved spring, different strain gauges are installed in several positions to record the strain in the models during the application of compression load. The results reveal that the geometry and material characteristics have an important effect on the stiffness value of the spring. Furthermore, finite element simulations of models are performed, and results are compared with those of experimental tests. The results from the experiments, as well as model and finite element simulation, show the curved spring's potential to be used in the developed VSB system and can be installed as a lateral resistance system in a structure subjected to vibration excitation such as an earthquake. Finally, the efficiency of the aforementioned system is evaluated via pushover analysis in a bare frame via finite element simulation. The results from pushover analysis illustrate the efficiency of the variable stiffness bracing system in framed structures

Response modification factors for reinforced concrete structures equipped with viscous damper devices

The response modification factor is one of the seismic design parameters that determine the nonlinear performance of building structures during strong earthquakes. Most seismic design codes lead to reduced loads. Nevertheless, an extensive review of related literature indicates that the effect of viscous dampers on the response modification factor is no longer considered. In this study, the effect of implementing viscous damper devices in reinforced concrete structures on the response modification factor was investigated. Reinforced concrete structures with different stories were considered to evaluate the values of the response modification factors. A nonlinear statistic analysis was performed with finite element software. The values of the response modification factors were evaluated and formulated on the basis of three factors: strength, ductility, and redundancy. Results revealed that the response modification factors for reinforced concrete structures equipped with viscous damper devices are higher than those for structures without viscous damper devices. The number of damper devices and the height of buildings have significant effects on response modification factors. In view of the analytical results across different cases, we proposed an equation according to the values of damping coefficients to determine the response modification factors for reinforced concrete structures furnished with viscous damper devices