The critical length of grade on two-lane rural roads is used as criterion to assess the need of ascending lanes for heavy vehicles. To estimate it, a speed profile is needed, which depends on the road’s grade and length, and on the physical, dynamic and mechanical characteristics of heavy vehicles. The Chilean standard uses a speed profile for a design truck that have a weight-to-power ratio of 120 kg/kW and an entrance speed of 88 km/h. This unique model prevents from studying cases in which the entrance speed can be different or in which the design vehicle is significantly different to the design speed of standards due to local conditions and consequently, does not allow estimating realistic critical lengths of grades. In this work, speed profiles models based on acceleration and force equilibrium were simulated, considering weight-to-power ratios between 120 and 263 kg/kW, entrance speeds between 80 and 100 km/h. Several values of critical lengths of grades were estimated, which offers engineers more options when designing ascending slopes.

Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 5-16. ISSN 0718-5073. http://dx.doi.org/10.4067/S0718-50732015000100001

Conventional non-reinforced concrete is a brittle material with a low tensile strength and low strain capacity. To improve these mechanical properties of concrete, fibers have been used in the last decades in structural engineering applications in Colombia, South America. In this document, the authors present the mechanical behavior of cantilever beams built with three different concrete mixes: one conventional reinforced concrete mix and two steel fiber reinforced concrete mixes with two percentages of metallic fiber addition (15 kg/m3 and 30 kg/m3). The beams were tested with cyclic displacements applied with a dynamic actuator in order to evaluate the hysteresis loops and the energy dissipation capacity. Based on the results, and for the same displacement, the steel fiber reinforced concrete beams dissipates 160 % more energy than conventional reinforced concrete beams. Additionally, metallic fibers reduce the quantity and length of cracks for high displacement levels. These characteristic could be beneficial for structural applications and specifically for improving the seismic performance of concrete structures.

Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 17-31. ISSN 0718-5073. http://dx.doi.org/10.4067/S0718-50732015000100002

As environmental issues become increasingly important, the buildings have focused on energy efficiency and energy needed for the construction and production of material. This research shows a simplified life cycle analysis study of operational and embodied energy of four new houses located in Temuco - Chile, structured with SIP (Structural insulated panel), in order to quantify the energy at each stage of this construction system. To obtain embodied energy were used two international databases in order to quantify the energy of each material, and the energy contained in the process relating with structure SIP was determined through measures in a company specializing in SIP construction. For the operational energy, computational models were carried out with Design Builder software, and this energy was projected at 50 years lifespan. The analysis of the data obtained show that the energy contained by construction processes represents about 1.7% of embodiedenergy, while the total embodied energy represents 11% of the total life cycle energy of houses, the remaining 89% represents the energy of occupation. On the other hand, we observe that SIP houses generate figures close to 60% savings in energy demand, compared to a masonry houses commonly built in this city.

Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 33-38. ISSN 0718-5073.  http://dx.doi.org/10.4067/S0718-50732015000100003

This work studies the factors that impact on the fire resistance of stud connections in steel–concrete composite structures, considering beams with solid slab. The design of the experiment, the thermal modeling of the push-out specimens, with or without fire protection material, and the analysis of the significance of the different parameters in the temperature relationships are carried out. Finally, the temperatures that should be considered in the concrete and the connector, expressed as percentages of the steel flange temperature, are proposed in order to determine the reduction factors of the connection resistance in fire situation. The results demonstrate that the percentages proposed in EN 1994-1-2 (2005) to determine the temperature in the concrete and the connector, based on the temperature in the steel flange, are not valid for all design situations within the scope of the code.

Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 39-52. ISSN 0718-5073. http://dx.doi.org/10.4067/S0718-50732015000100004

In this work, the behaviour of stud shear connectors in composite structures is studied, starting from the via numeric simulation of the push out test in a steel beam – with solid concrete slab concrete section is studied. The study considers material non-linearity material of concrete and steel, adopting firstly a bilinear model for both (steel and concrete), and in the second case, to the difference ofdiffering from other authors, the concrete damage plasticity of the concrete. ABAQUS is used to model the push out test. The basis and methodology of the modelmodelling process push out test are explained. The numerical results obtained are in accordance with the experimental results, which . This aspect shows the efficacythat of the finite element method is efficient for the in studying the behaviour of stud shear connector’s behavior. Finally, the capacities of shear connections obtained from the finite element analysis were are compared with to the connection strengths calculated using the American Specification (AISC-LRFD (2005)), European Code (Eurocode 4 (2004)) and Cuban Code (NR-080-2004). ItThis was is observed that, these specifications over estimate this value (capacities of shear connections) in many cases.

Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 53-68. ISSN 0718-5073.  http://dx.doi.org/10.4067/S0718-50732015000100005

The wood construction industry requires data of the mechanical strength of wood with dimensions and classification suitable to be used as structural elements. This research proposes an experimental strategy for the mechanical characterization of wood beams and their application as an engineering material. The objective of the research was to determine the wave speeds and moduli of elasticity of Pinus spp. beams using ultrasound and stress waves, studying 70 Pinus spp. beams with dimensions of 0.10 m x 0.15 m in the transverse direction, 35 beams of 5 m and 35 of 6 m length. The speeds of transmission showed coefficients of variation consistent with the structural heterogeneity of wood. The values of these coefficients increased when the second-level characteristics were calculated, as in the case of the moduli of elasticity. The speed and the modulus of elasticity showed an important anisotropy character for the calculus of the mechanical strength of the beams. Likewise, the parameters calculated with the stress wave method were higher than those determined by ultrasound. The results allow concluding that theultrasound and stress wave techniques can determine the speed wave and the modulus of elasticity of Pinus spp. wood beams.

Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 69-79. ISSN 0718-5073.  http://dx.doi.org/10.4067/S0718-50732015000100006