The replacement of natural materials by industrial by-products has given a variety of new construction materials that are economically viable and ecologically beneficial. Blast furnace slag is one of these industrial by-products. Its beneficial proprieties and characteristics have led to rapid growth of production in Algeria and worldwide. This research deals with the effect of alkaline activation of slag cement with clinker. Various agents that activate the process were used for testing, and it showed that compressive strength at 28 d, which reached 150% with respect to compressive strength obtained from slag cement at different percentages of slag (50%–80%), increased considerably. Alkaline activators accelerate hydration and stimulate the hardening process. The results also show the efficacy of steam cured treatment on the compressive strength.Key words: slag cement, activation agent, hydration, hardening, steam curing.

It is now widely recognized that the masonry infill frame used in reinforced concrete structures (RC) greatly enhances both the rigidity and strength of the surrounding frame. The lateral loading behavior of this RC frame is different from the frame without infill, although the structural contribution of infill walls is discarded in many countries, including Algeria. This paper aims to focus on the effect of openings and the effect of changing the distribution of masonry panels on the global behavior of buildings. For this, a pushover analysis is carried out to evaluate the seismic performance and assess the behavior of infilled RC, and to study the results related to capacity curve, inter-story drift and energy. The results obtained show that the effect of the openings and changing of the distribution of masonry panels can drastically change the overall behavior of the structures regarding enhancing strength capacities and energy absorption. Noticeable remarks in terms of distributing masonry panels within a frame are observed and several recommendations concerning the present practice might be important to be considered.

Optimum design in civil structures like domes and vaults is a very old and ongoing research field. These structures are preferably designed to transport loads via membrane action. In this paper, we have considered a reinforced concrete dome and vault, where the bending moment and strain energy were used as objective function to be minimized using genetic algorithm, and model reduction method by proper orthogonal decomposition based on the results of finite element analysis of gradually changed design parameters. The proposed approach results are of a high accuracy compared to finite element based optimization.