Construction Rehabilitation in Civil Engineering at bachelor degree level: A guideline course

ABSTRACT: In general terms, construction rehabilitation is not sufficiently studied worldwide in civil engineering schools. This article proposes an international guideline course on construction rehabilitation for civil engineering students at the bachelor degree level. As we live in an increasingly globalized world, the course aims to prepare students in the same basic concepts so the course content and its focus can be common for all civil engineering programs worldwide. Nevertheless, the course should be considered as a general guideline. At each university, special attention should be paid to the topics that are most common due to the varying construction practices, preservation laws and regulations, and legal jurisdiction governing the scope of practice in construction rehabilitation that exist in the region/country in which the university is located. Moreover, the guideline course should be focused on existing building types, both significant historic ones and those that make up the day-to-day rehabilitation market. To achieve this, the initial step of the methodology was the study and integration of the results obtained in a survey sent to lecturers at 89 universities in 30 countries around the world. Then, a preliminary grouping was done of topics that could be included in the course, preassigning a teaching time to each topic. Later, various renowned experts in the matter audited the tentative guideline course. Finally, based on their opinions and comments, the definitive guideline course was rewritten. Through this course, civil engineering students will improve their ability to recognize, analyze, diagnose, and solve problems that commonly appear in existing buildings, and they will increase their knowledge about maintaining and conserving them

Fatigue limit of recycled aggregate concrete

This paper presents the main results of the research carried out to obtain the fatigue limit of concrete incorporating recycled aggregate from concrete. In this research, recycled aggregate concretes with partial and total coarse aggregate replacement and control concretes with different increasing water/cement ratios have been cast to study the material’s behavior in response to repeated compressive loads. The results show that, for the same water/cement ratio, the recycled aggregate concretes present a loss of stiffness higher than the control concrete. Furthermore, the use of recycled aggregate in concrete implies a reduction of the fatigue life. These differences are increased for low water/cement ratios, as in this case the main factor is the lower strength capacity of the aggregate. From the results obtained, recommendable mixtures for recycled aggregates exposed to fatigue loads are proposed

Kinesin expands and stabilizes the GDP-microtubule lattice

Kinesin-1 is a nanoscale molecular motor that walks towards the fast-growing (plus) ends of microtubules, hauling molecular cargo to specific reaction sites in cells. Kinesin-driven transport is central to the self-organization of eukaryotic cells and shows great promise as a tool for nano-engineering1. Recent work hints that kinesin may also play a role in modulating the stability of its microtubule track, both in vitro2,3 and in vivo4, but the results are conflicting5,6,7 and the mechanisms are unclear. Here, we report a new dimension to the kinesin–microtubule interaction, whereby strong-binding state (adenosine triphosphate (ATP)-bound and apo) kinesin-1 motor domains inhibit the shrinkage of guanosine diphosphate (GDP) microtubules by up to two orders of magnitude and expand their lattice spacing by ~1.6%. Our data reveal an unexpected mechanism by which the mechanochemical cycles of kinesin and tubulin interlock, and so allow motile kinesins to influence the structure, stability and mechanics of their microtubule track

Sequential Assembly of Centromeric Proteins in Male Mouse Meiosis

The assembly of the mitotic centromere has been extensively studied in recent years, revealing the sequence and regulation of protein loading to this chromosome domain. However, few studies have analyzed centromere assembly during mammalian meiosis. This study specifically targets this approach on mouse spermatocytes. We have found that during prophase I, the proteins of the chromosomal passenger complex Borealin, INCENP, and Aurora-B load sequentially to the inner centromere before Shugoshin 2 and MCAK. The last proteins to be assembled are the outer kinetochore proteins BubR1 and CENP-E. All these proteins are not detected at the centromere during anaphase/telophase I and are then reloaded during interkinesis. The loading sequence of the analyzed proteins is similar during prophase I and interkinesis. These findings demonstrate that the interkinesis stage, regularly overlooked, is essential for centromere and kinetochore maturation and reorganization previous to the second meiotic division. We also demonstrate that Shugoshin 2 is necessary for the loading of MCAK at the inner centromere, but is dispensable for the loading of the outer kinetochore proteins BubR1 and CENP-E

Dynamic identification and condition assessment of an old masonry chimney by using modal testing

The renovation of old industrial sites for modern use requires the knowledge of the health status of old structures in order to ensure their use in safety conditions. The main goal of this paper is to assess the dynamic behavior of a masonry industrial chimney built in Spain in the early XX century. The paper also focuses on determining health status of the structural system and understanding where the errors and uncertainties of the numerical modelling are originated. The chimney is 38.30 m high and is founded on a concrete truncated pyramid. The paper shows the different test carried out in laboratory to obtain the mechanical parameters of the materials by means of analyzing the bricks and mortar before doing the dynamic study. After that, the chimney has been monitored for the study of the dynamic behavior and the results provided from the ambient-vibration and modal testing are presented in the paper. To this aim, Operational Modal Analysis (OMA) is used to determine the dynamic characteristics of the chimney including natural frequencies and modes shapes. The outcomes of the experimental analysis have been compared with the numerical results updating the Finite Element (FE) model used for the theoretical simulation of the chimney. The results show that the health status of the chimney is satisfactory and the combination of gravitational and wind loads do not supposes a risk for the physical integrity of the structure