Generally, it has been seen that symmetrical shape buildings behave much better than unsymmetrical. The authors carried out nonlinear static analysis of regular and irregular shaped RC framed buildings under seismic excitation. One G+8 story RC frame building chosen. Different shapes of the building considered were: square, plus, T and inverted L. For analysis, 3D models of all shapes were developed and ETABS software used to carry out the seismic analysis. The IS code 1893 (Part 1) (2002) was used for analysis with equivalent static method and response spectrum approach. Apart from these two methods, pushover analysis technique was also used. The loadings were as per IS Code 875 (Part 1 and Part 2). The building was assumed to be located in seismic zone III of the country. After analysis, various parameters were compared for different chosen models. In the analysis, only bare frame for all models was considered. No soil foundation effects were considered. In the earthquake, soil structure is an important parameter and it was included too. The results show that plus-shaped model has the highest value of displacement as compared to other three models, and L-shaped model is the least. The square-shaped model has maximum value and T-shaped has the lowest value for axial force as compared to others. The observation shows that square shape has maximum value for bending moment, and again L-shaped has the least bending moment. The time period is maximum for plus-shaped model showing its flexibility. T-shaped model has least time period, meaning it is quite rigid. The square-shaped model has the maximum base shear as compared to other three. Under the action of lateral loads, pushover analysis showed multiple performance levels for a given structural model. It is permissible for a given structure to obey these performance levels and perform until the safety performance levels are achieved. The authors concluded that the structure with simple geometry performs better during earthquake excitations.

The second paper, "Seismic Response Analysis of RC Silo Under the Influence of Soil-Structure Interaction" by Rutuja Gadivaddar and M Manjunath, analyzes the behavior of unbraced and braced RC silo under seismic excitation, including the effect of soil structure. In seismic analysis, assumptions are made for structural support such as base fixed conditions and base flexible conditions. The behavior of the structure when assumed as fixed base will be different but considering it with inclusion of Soil-Structure Interaction (SSI) makes it more realistic. The study includes analysis of RC silo in different seismic zones of the country with different soil conditions. The analytical model developed for silo was analyzed with different height-to-diameter ratios. Further comparison was made between braced and unbraced silo behavior. In the study, Airy's theory of silo analysis was preferred over Janssen's theory, and the height-to-diameter ratio was kept as 2, 2.5 and 3. Modeling and analysis were done with the help of STAAD Pro V8i software using equivalent static method. The unbraced and braced silo were considered to have fixed base and also flexible base to include the effect of SSI. Based on the results, it was found that inclusion of SSI effect makes the structure flexible and its time period and displacement increases, base shear reduces as compared to fixed base condition. This was found for both braced and unbraced silo and also for different height-to-diameter conditions. Further, base shear, displacement and natural time period increase as soil types vary from hard to medium to soft. It was also noticed that base shear, displacement and natural period values are higher for zone V than for zone IV of the country. The results obtained are not surprising as these phenomena are well established. With increase in the height of silo, the base shear, displacement and natural time period values increase. When the silo is provided with cross bracings, it results in increase of base shear, but displacement and time period reduce as compared to unbraced silos. The last paper, "Optimization of Recycled Concrete as Aggregate for Structural Concrete" by Daheem Hussain Bhat and Manish Kumar, utilizes recycled concrete as aggregate for making structural concrete. In the preparation of structural concrete, the aggregate used must be according to established specifications to achieve the design strength. Once recycled concrete is used as aggregate for making concrete, it may not exactly be as per code specifications. In that case, whether the designed strength is obtained or not remains to be seen. In this study, the authors used three different water-cement ratios and varying percentages of recycled concrete aggregate ranging from 0 to 20%. Various materials used include: ordinary portland cement, silica fumes, superplasticizers, locally available crushed granite stone as coarse aggregate, locally available river sand, recycled concrete aggregate obtained from laboratory cast concrete and ordinary drinking water to achieve High Performance Concrete (HPC) M60 grade. For different water-cement ratios, the quantities of materials required were worked out. Experimental works were done on test specimens to determine the workability achieved and strength of HPC utilizing silica fumes. Optimization was done using Minitab software to achieve the best combination of materials for the HPC.