In-situ strength assessment of concrete - The European Concrete Frame Building Project (Reprinted from Non-Destructive Testing Civil Engineering, April, pg 583-592, 2000)

A full-scale seven-storey in-situ advanced reinforced concrete building frame was constructed in the Building Research Establishment's Cardington laboratory encompassing a range of different concrete mixes and construction techniques. This provided an opportunity to use in-situ non-destructive test methods, namely Lok and CAPO tests, on a systematic basis during the construction of the building. They were used in conjunction with both standard and temperature-matched cube specimens to assess their practicality and their individual capabilities under field conditions. Results have been analysed and presented to enable comparisons of the performance of the individual test methods employed.

Design optimization of cold-formed steel portal frames taking into account the effect of building topology

Cold-formed steel portal frames are a popular form of construction for low-rise commercial, light industrial and agricultural buildings with spans of up to 20 m. In this article, a real-coded genetic algorithm is described that is used to minimize the cost of the main frame of such buildings. The key decision variables considered in this proposed algorithm consist of both the spacing and pitch of the frame as continuous variables, as well as the discrete section sizes.A routine taking the structural analysis and frame design for cold-formed steel sections is embedded into a genetic algorithm. The results show that the real-coded genetic algorithm handles effectively the mixture of design variables, with high robustness and consistency in achieving the optimum solution. All wind load combinations according to Australian code are considered in this research. Results for frames with knee braces are also included, for which the optimization achieved even larger savings in cost.

Reliability Assessment of 3-D Space Frame Structures Applying Stochastic Finite Element Analysis

Throughout design development of satellite structure, stress engineer is usually challenged with randomness in applied loads and material properties. To overcome such problem, a risk-based design is applied which estimates satellite structure probability of failure under static and thermal loads. Determining probability of failure can help to update initially applied factors of safety that were used during structure preliminary design phase. These factors of safety are related to the satellite mission objective. Sensitivity-based analysis is to be implemented in the context of finite element analysis (probabilistic finite element method or stochastic finite element method (SFEM)) to determine the probability of failure for satellite structure or one of its components.

Long-term graft survival in patients with flexible open-loop anterior chamber intraocular lenses

Purpose. To evaluate the long-term graft survival in patients with flexible open-loop anterior chamber intraocular lenses (AC IOL). Methods. We retrospectively reviewed the records of patients with aphakic/pseudophakic bullous keratopathy who underwent penetrating keratoplasty and flexible open-loop AC IOL implantation in our institution from 1983 to 1988. Results. 79 eyes from 77 patients were included in the study. Mean follow-up was 50 months (range 1 to 123 months). At last follow-up 61 eyes (77.2%) had clear grafts. Among them, the visual acuity was = 20/40 in 14 eyes (23.0%), 20/50-20/100 in 22 eyes (36.1%), 20/200-20/400 in 9 eyes (14.8%) and = CF in 16 (26.2%). Increment of glaucoma medications and/or glaucoma surgery was the most frequent complication (37 eyes, 46,8%). Cystoid macular edema was newly diagnosed in 10 eyes (12.7%). Conclusions. Flexible, open-loop anterior chamber lens are a viable option in the treatment of patients with aphakic or pseudophakic bullous keratopathy undergoing penetrating keratoplasty.

Long-term graft survival in patients with flexible open-loop anterior- chamber intraocular lenses

Purpose. To evaluate the long-term graft survival and complications of flexible, open-loop anterior-chamber intraocular lenses in patients with penetrating keratoplasty for pseudophakic or aphakic bullous keratopathy. Methods. We reviewed charts of all consecutive patients who underwent penetrating keratoplasty for pseudophakic or aphakic bullous keratopathy combined with implantation of a flexible, open-loop, anterior-chamber intraocular lens at our institution between 1983 and 1988. One-hundred one eyes of 99 patients were evaluated. Graft-survival rates were calculated by using the Kaplan-Meier actuarial method. Results. Mean follow-up was 49.8 months (range. 1-144). The probability of graft survival at 1, 2, 4, 6, and 8 years was 93, 87, 78, 65, and 65%, respectively. A total of 25 (24.8%) grafts failed. Progressive corneal edema without signs of rejection was the most common finding in patients with failed grafts (10 eyes, 40%). The most frequent complication observed was newly diagnosed or worsening of preexisting glaucoma (46 eyes, 45.5%). Conclusions. Our long-term results support flexible, open-loop anterior-chamber intraocular lenses as a reasonable option, at the time of penetrating keratoplasty, in patients with pseudophakic and aphakic bullous keratopathy.