Next generation structural silicone glazing
This paper presents an advanced engineering evaluation, using nonlinear analysis of hyper elastic material that provides significant improvement to structural silicone glazing (SSG) design in high performance curtain wall systems. Very high cladding wind pressures required in hurricane zones often result in bulky SSG profile dimensions. Architectural desire for aesthetically slender curtain wall framing sight-lines in combination with a desire to reduce aluminium usage led to optimization of silicone material geometry for better stress distribution. To accomplish accurate simulation of predicted behaviour under structural load, robust stress-strain curves of the silicone material are essential. The silicone manufacturer provided physical property testing via a specialized laboratory protocol. A series of rigorous curve fit techniques were then made to closely model test data in the finite element computer analysis that accounts for nonlinear strain of hyper elastic silicone. Comparison of this advanced design technique to traditional SSG design highlights differences in stress distribution contours in the silicone material. Simplified structural engineering per the traditional SSG design method does not provide accurate forecasting of material and stress optimization as shown in the advanced design. Full-scale specimens subject to structural load testing were performed to verify the design capacity, not only for high wind pressure values, but also for debris impact per ASTM E1886 and ASTM E1996. Also, construction of the test specimens allowed development of SSG installation techniques necessitated by the unique geometry of the silicone profile. Finally, correlation of physical test results with theoretical simulations is made, so evaluation of design confidence is possible. This design technique will introduce significant engineering advancement to the curtain wall industry.
Seismic Racking Test Evaluation of Silicone Used in a Four-Sided Structural Sealant Glazed Curtain Wall System
This paper presents the results of a study in which four-sided structural sealant glazing (SSG) insulating glass curtain wall units were subjected to cyclic racking test methods in accordance with AAMA 501.6 testing protocols. The test configuration included three side-by-side primary units and a corner unit. High-resolution cameras were utilized to capture instantaneous images during the racking test so that the displacement within the sealant joint could be captured and isolated from the displacement of the entire glazed unit. Drift capacity of the system in terms of glass attachment and sealant performance is reported in detail for different levels of racking displacements and boundary conditions. The overall behavior of the system is characterized, and specifically the sealant performance at a corner condition during racking drift is discussed. Additionally, expected strains in the sealant were calculated using a linear-elastic finite element model and were then compared with the strains the actual structural sealant joint underwent during system testing. Silicone sealant damage was evaluated using visual observation before and after cyclic racking. The paper discusses proposed acceptable sealant stress levels for seismic design and the durability of silicone used in the SSG system as compared to dry-glazed systems based on glass performance.
Treatment of oily wastewater by organic–inorganic composite tubular ultrafiltration (UF) membranes
A tubular UF module equipped with polyvinylidene fluoride membranes modified by inorganic nano-sized alumina particles was used to purify oily wastewater from an oil field. The membrane water permeations of the UF process were analyzed. Retentions of chemical oxygen demand and total organic carbon were more than 90% and 98%, respectively. The results indicate that after UF treatment, oil content was below 1 mg/L, suspended solids content was below 1 mg/L, and solid particle median diameters were less than 2 μm. The quality of the permeation water met the requirement by oilfield injection or drainage. Fouled membranes and washed membranes were analyzed by scanning electron microscopy, and fouled membranes were backwashed with different solutions. Results show that the addition of nanosized alumina particles improved membrane antifouling performance, and the flux recovery ratio of modified membranes reached 100% washing with 1 wt% of OP-10 surfactant solution (pH 10).