Considerations on the explosion resistant design of special infrastructures have increased in the recent

years. Amongst the various types of infrastructures, road and railway tunnels have a unique importance due to their

vital role in connection routes in emergency conditions. In this study, the explosion effects of a projectile impacting on

a railway tunnel located in a jointed rock medium has been simulated using 2D DEM code. Primarily, a GP2000

projectile has been considered as a usual projectile and its penetration depth plus its crater diameter were calculated

in rock mass. The blast pressure was, then, calculated via empirical formula and applied on the boundary of crater as

input load. Finally, the wave pressure propagation through the jointed rock medium was investigated. In part of the

study a sensitivity analysis has been carried out on jointed rock parameters such as joint orientation, dynamic modulus

and damping ratio. Their effects on tunnel lining axial force as well as bending moment have also been investigated.

Elevated water tanks as one of the main lifeline elements are the structures of high importance. Since they are extremely vulnerable under lateral forces, their serviceability performance during and after strong earthquakes is a matter of concern. As such, in recent years, the seismic behavior of water tanks has been the focus of a significant amount of studies. In the present work, three reinforced concrete elevated water tanks, with a capacity of 900 cubic meters and height of 25, 32 and 39 m were subjected to an ensemble of earthquake records. The behavior of concrete material was assumed to be nonlinear. Seismic demand of the elevated water tanks for a wide range of structural characteristics was assessed. The obtained results revealed that scattering of responses in the mean minus standard deviation and mean plus standard deviation are approximately 60% to 70 %. Moreover, simultaneous effects of mass increase and stiffness decrease of tank staging led to increase in the base shear, overturning moment, displacement and hydrodynamic pressure equal to 10 - 20 %, 13 - 32 %, 10 - 15 % and 8 - 9 %, respectively.

Energy conservation in buildings plays a vital role for sustainable development of societies and nations. Although, newer buildings in developing nations are being constructed using energy conservation approach, existing buildings have higher energy demand to meet the desired comfort. Excessive energy demand for cooling the built environment is a major problem over most of the arid climatic zones. The problem is predominant in all the top storied buildings which are directly under exposed roof condition. In order to reduce the overheating of the roof surface a composite combination of reflecting-cum-insulating (R-I) material was developed. The sustainable materials viz., expanded polystyrene (construction waste), saw dust (industrial waste), and the false ceiling panels prepared from industrial waste were used for the development of sustainable R-I material. The R-I material was retrofitted over the existing roof of a model room in an educational building over composite climate (Nagpur, India) and was analyzed experimentally for the period of a year. The thermal resistance of the overall roof assembly was increased from 0.28 to 0.55 m² K/W, which in turn helped to achieve 16% of the duration of the year under thermal comfort. The developed R-I material has also an advantage of low cost (INR 900 per sq. m.) of installation as well as light weight (50 kg/m²) retrofitting solution. The R-I product can further be applied on larger roof areas by the designers to reduce the cooling load of the built environment as well as increase the occupants comfort over the local climatic zone.

The paper presents the characterisation of an Algerian natural pozzolan (NP) intended to for use in cement-based materials. The experimental programme was based on different tests on paste and mortar. The pozzolanic activity was assessed by the means of lime consumption over time of mixtures of lime-pozzolan (75% NP and 25% Ca(OH)₂, water-binder ratio of 0.45). The degree of reactivity was assessed by observing the crystallographic changes (XRD) and lime consumption (TG) up to 1 year of hydration. The effect of NP on cement-based mixtures was based on the measurement of the water demand and setting time of pastes, and on the compressive strength of mortars, up to one year. The replacement rates of cement by pozzolan were 5, 10 and 15%. A superplasticizer was used (0, 1, 2 and 3% of the binder mass). A calculation of the carbon footprint was investigated in order to assess if the natural pozzolan could be considered as eco-efficient when used in replacement of the clinker. The results showed that NP had a medium pozzolanic reactivity and with a medium-low silica content. The use of NP usually led to a small increase in the water/binder ratio (up to 10%) to maintain constant workability. The setting time was also increased by around 20%. Nevertheless, strength tests showed that the pozzolan had sufficient activity to counteract the water demand, since long-term compressive strength of the binary system (cement + pozzolan) were higher than those of cement alone. The use of NP in replacement of clinker involves a reduction in CO₂ emissions for transport up to 1800 km, which is compatible with sustainable development. The results are most promising from both a performance-based and an environmental point of view

In this paper, the assessment of four short-span steel bridges from 24 to 42 m under local overloaded trucks and ground motion records are presented and discussed. Bridges were virtually located in Mexico, and so the vehicular live loads, earthquake loads due to local seismicity, and other local loads were adapted in the design. A realistic condition of the local design truck for Mexico was selected from survey traffic flows reported for local highways. Nonlinear dynamic analyses were carried out using seven historical records associated with the largest vertical intensities from subduction earthquakes in Mexico. Results are intended to evaluate the local practice, which frequently adopts the current AASHTO LRFD Specifications in the absence of an official local design code for bridge structures. Thus, this research pretends to provide design recommendations for short-span steel bridges in Mexico.

Pre-cast concrete products are sometimes manufactured in 2 cycles per day with one mold for the purpose of productivity improvement and so forth. In such a case, from the point of view of securing early-time strength which is required at the time of demolding, it is necessary to increase steam curing temperature and then the likelihood of temperature cracking becomes a concern. Moreover, self-compacting concrete (hereinafter refer as “SCC”) is increasingly used to which ground granulated blast-furnace slag is added, in consideration of environment surrounding a plant or operation environment. One choice then is to admix expansive agent in order to prevent cracking due to autogenous shrinkage. However, there is some possibility that high temperature curing required for 2 cycles per day production likely enhances cracking due to expansive agent admixing. In this study, the cause of cracking of large-sized pre-cast concrete products with high amount of expansive agent, in comparison of 1 cycle per day and 2 cycles per day productions was investigated.

As the result, it was confirmed that high temperature steam curing and early demolding of 2 cycles per day production promote thermal stress cracking in contrast to 1 cycle per day production, and at the same time, un expected cracking along main reinforcement is caused by excess expansion due to inappropriate curing of expansive agent.

Bridges normally undergo nonlinear deformations during a near field strong ground motion resulting in a critical deviation of their columns from the plumb state due to considerable residual deformations. These excessive residual deformations make a bridge, which has not collapsed, ‘irreparable’ and in turn ‘not operable.’ Therefore, reasonable prediction of these types of bridge piers deformations is of great importance in order to evaluate the serviceability of bridges subjected to a seismic scenario. Conventional hysteresis models formulated for typical concrete columns are normally used for this purpose which most of times fail to correctly predict the residual deformations occurred as a result of a one-sided or directivity pulse excitation. The present research aims at development of a peak oriented hysteresis model being able to regenerate residual deformations more reasonable compared to the conventional hysteresis models. This multi linear peak oriented model considers strength deterioration in each half cycle in addition to stiffness degradations in unloading cycles. Yielding points differ in both positive and negative sides of the hysteresis model that enables us to define a different elastic stiffness of both sides in asymmetric concrete sections. Another remarkable property of this model is breaking points and strength deterioration in unloading and reloading stages. This work also compares the obtained results to the conventional hysteresis models, namely bilinear, Clough, Q-Hyst, Takeda and Bouc-Wen in terms of prediction of residual nonlinear deformations in cyclic or dynamic analysis of reinforced concrete single-column bridge piers. The obtained results prove higher relative accuracy of the proposed model.