Structural grouting of load-bearing precast concrete elements: Issues and solutions

The purpose of this paper is to raise construction industry awareness regarding structural grouting of precast concrete projects in the United States. Incidents related to structural grouting have occurred with both precast concrete systems and other building systems. Designers, architects, owners, insurance carriers, and the construction industry in general are becoming increasingly aware of deficient grouting installation methods and verification procedures. Concerns include the timeliness of grout installation during the erection process, the lack of grout on some components of finished projects, and the poor quality of installed grout. These concerns pertain to horizontal connection joints of critical load-bearing elements between foundations and precast concrete columns and walls, stacked precast concrete columns, and stacked precast concrete walls. Current building codes and standards provide no requirements and limited guidance for the installation or special inspection of these critical horizontal joints. In an effort to address this gap in building codes and standards, as it specifically relates to precast concrete structural products, some precast concrete producers and erectors are implementing several strategies and new procedures, as noted and further developed in this paper.

DETAILS OF NORMAL SECTIONS STRENGTH CALCULATION OF FLEXIBLE REINFORCED CONCRETE STRUCTURES BY THE WOOD’S METHOD IN PC "LIRA SAPR"

Problem statement. The problem of realization of the calculation method of normal cross-sections strength of reinforced concrete constructions under flat bending, which is established in the current building codes of Ukraine, is considered. The main attention is paid to atypical and practically not considered calculation cases, typical for automated algorithms in the environment of SP "LIRA SAPR". The purpose of the article. Analysis of the feasibility of using the calculation method of current building codes with further development of recommendations, based on the specifics of computerized calculations. Methodology. Within the framework of the performed research, rectangular cross-sections of reinforced concrete structures with single and double reinforcement (provided a significant increase in the area of reinforcement of the compressed cross-sectional area) with variation of concrete classes, reinforcement coefficient and ratio of reinforcement areas were considered. The stress-strain diagrams of concrete and reinforcement are bilinear with characteristic values set for the first group of limit states. The character of change of cross-sections’ status diagrams "M - εc(1) " is investigated. Research results. It is found that for single-reinforced sections with decreasing reinforcement area there is a decrease of the value of deformation of the compressed fiber of concrete, which is used to find solutions for systems of nonlinear equilibrium equations of the deformation method. This leads to an increase of the execution time of calculations of the flat elements’ reinforcement by the Wood method. It is established that for sections with double reinforcement at relatively large values of the ratios of the reinforcement areas, the equilibrium of the section is at the maximum deformations of the compressed concrete fiber. Conclusions. An approach aimed at accelerating the calculation of sections with single reinforcement, which is based on the use of the relationship between the percentage (area) of reinforcement and the deformation of the most compressed fiber of the reinforced concrete element. Features of analytical algorithms for calculating the selected sections are taken into account by implementing this technique in the PC "LIRA SAPR", optimization and acceleration of automated algorithms for calculating reinforced concrete structures.

CONCEPTUAL DESIGN. STAGES OF FORMATION

Conceptual design is the most creative part of architectural activity. In the professional work of architects, conceptual design is given great importance. Various architectural and design forums, exhibitions, competitions are dedicated to him. In Soviet times, an interesting example of the formation of conceptual solutions is the work of Alexander Brodsky and Ilya Utkin (who signed their works as a tandem of "Brutus"). We have other solutions of interesting concepts - the object of the competition "The World of El Lysytsky" - the Globe Theater in Novosibirsk. Here the authors start from the main idea - that the cube is the main form that characterizes the spirit and style of the Russian avant-garde of the twentieth century. Conceptual design ideas are implemented in the construction of unusual hotels, atypical urban environment, non-traditional building materials. All this allows you to think about life according to other rules. Than those prescribed in building codes. The world around us is more interesting and diverse, so we can, in part, paint it in bright colors.

Evaluating the Impact of Energy Efficiency Building Codes for Residential Buildings in the GCC

In arid climates, almost half of the urban peak load of energy demand is used to supply cooling and air-conditioning in the summertime. The pressure placed on energy resources to satisfy inhabitants’ indoor comfort requirements is mounting due to accelerated urbanisation rates in developing countries and has led countries such as those in the GCC (Gulf Cooperation Council) to establish sustainable building codes to enhance their environmental performance. Using the extensive parametric energy simulations provided by DesignBuilder, this study addresses the potential of applying different GCC energy efficiency measures to reduce annual energy consumption and carbon emissions in a typical residential dwelling in the Kingdom of Bahrain. To do so, first, a base case validation simulation model was generated, followed by four design scenarios addressing the minimum requirements for Bahrain’s Energy Conservation Code, Abu Dhabi’s ESTIDAMA 1, Saudi Arabia’s code, and Kuwait’s building code. Then, a feasibility study was conducted using the simple payback period (SPP) and lifecycle cost (LCC) analysis. Overall energy and carbon emission (CO2) reduction showed the potential for building sustainable codes to improve building environmental performance throughout the year. In terms of energy performance and CO2 reduction, Abu Dhabi’s ESTIDAMA 1 code recorded the best energy savings at a 24.4% and a 26.3% reduction in carbon emissions, followed by the Saudi code with a 14.6% annual energy savings and 12.3% less carbon emissions. Regarding the economic analysis, although the SPP indicates the Bahraini code offered payback in just under two years for subsidised energy and half a year for unsubsidised, the LCC analysis suggests that applying Abu Dhabi’s ESTIDAMA 1 code was the most feasible, followed by the Saudi building code. Consequently, the study suggests a comprehensive evaluation of the relationship between the sustainable building codes and their economic feasibility in order to enhance and promote the wide application in the GCC based on the code’s capabilities and their benefits for residential households and the overall economy.

Assessment of Selected Models for FRP-Retrofitted URM Walls under In-Plane Loads

One way to improve a structure’s total load-bearing capacity during an earthquake is to apply fiber-reinforced polymers (FRP) to unreinforced walls. The study discusses the use of FRP to strengthen unreinforced masonry (URM) structures. Although, many studies were conducted on the FRP strengthening of URM buildings, most of them were experiments to investigate the success of retrofitting approaches, rather than developing a successful design model. A database of 120 FRP-reinforced wall samples was created based on the current literature. Various approaches for calculating the bearing capacity of FRP-reinforced masonry are presented and detailed. The findings of the experiments, which were compiled into a database, were compared to those derived using formulas from the literature and/or building codes, and the model’s limitations are discussed.

Evaluation of a new user-centric sensor-based lighting control approach for circulation areas

Suitable lighting control strategies are essential for energy efficiency in buildings. Occupancy sensors are highly promoted by the building codes as one of the most cost-effective solutions in the sector. However, widespread use of these systems is still limited due to lack of user satisfaction. In this study, it is hypothesized that the “conventional use” of occupancy sensors (where user steps inside a dark area, and only afterwards the area becomes lit) is the reason behind the dissatisfaction. To overcome this problem, a new user-centric sensor-based lighting control approach is proposed in this study where users walk into an already lit area. An experiment was carried out in the circulation areas of a university building to test the feasibility of the proposed scenarios along with a conventional occupancy sensor scenario and the existing “no sensor” scenario. The main results revealed that the conventional use of occupancy sensors was not favoured by the participants in circulation areas while use of the proposed user-centric approach was as favourable as the existing constantly lit situation. It is the claim of this study that both energy efficiency and user satisfaction can be provided by the use of user-centric control systems.

COMPARISON OF DETERMINATION OF SNOW LOADS FOR ROOFS IN BUILDING CODES OF VARIOUS COUNTRIES

The article compares the requirements for calculating the snow load on the coatings of buildings and structures in accordance with the regulations of technically developed countries and associations – Russia, the European Union, Canada and the United States. It was revealed that in these norms the general approaches, the subtleties of calculating the coefficients, the set of standard coatings and the schemes of the form coefficient proposed for them differ significantly. This situation reflects the general problem of determining snow loads – at the moment there is no recognized unified scientifically grounded approach to determining snow loads on coatings of even the simplest form. The difference in the normative schemes of snow loads is clearly demonstrated by the example of a three-level roof.

An exceedance probability of the influence in the Building Code

Во всем мире на картах сейсмической опасности приводятся наиболее вероятные значения сейсмических воздействий. В соответствии с допустимым риском эти значения могут быть увеличены. Например, в международных нормах для расчета сейсмостойкости радиационно-опасных объектов наиболее вероятные значения ускорений увеличиваются на величину стандартного отклонения. В отечественных строительных нормах предполагается использование наиболее вероятных значений. Считается, что вследствие различных факторов расчеты воздействий сопровождаются некоторыми погрешностями, вследствие чего оценки воздействий могут быть завышены на 10, 5 и 1% для карт ОСР А, В и С соответственно. Эти оценки были существенно увеличены при округлении оценок интенсивности до целочисленных значений баллов. Однако в пояснительной записке это не было отражено. Поэтому вместо 10, 5 и 1% для карт ОСР А, В и С следуют значения 50, 45 и 41% соответственно. Поскольку баллы нельзя непосредственно использовать в инженерных расчетах, согласно строительным нормам, производится пересчет баллов в ускорения по шкале MSK-64. Однако, еще создатели шкалы MSK-64 b карт ОСР и шкалы MSK-64 указывали, что шкала занижает оценки ускорений примерно в полтора раза. Причина – в шкале MSK-64 приводятся не реальные, а фильтрованные значения. Во время создания этой шкалы основная масса зданий имела не более 5 этажей. Фильтрацией удалялись низкочастотные составляющие, неопасные для существующих зданий. Цель работы – оценить реальную вероятность превышения уровня воздействий при расчетах сейсмостойкости зданий и сооружений. Методы исследования – анализ процедур оценки расчетных воздействий с использованием карт ОСР и строительных норм. Результаты работы – показано, что нормативный уровень ускорений при расчетах сейсмостойкости более, чем в два раза ниже реальных значений All over the world, the most probable values of seismic impacts are shown on seismic hazard maps. According to the acceptable risk, these values can be increased. In domestic building codes, it is customary to use the most likely values. It is believed that due to various factors, the impact calculations are accompanied by some errors, as a result of which the impact estimates may be overstated by 10, 5 and 1% for the general SRF maps A, B and C, respectively. However, these estimates were significantly increased when rounding the intensity estimates to integer values of the scores. However, this was not reflected in the explanatory note. Since the points cannot be directly used in engineering calculations, according to the building codes, the points are converted into accelerations on the MSK-64 scale. However, even the creators of the OSR maps and the MSK-64 scale indicated that the scale underestimates the acceleration estimates by about one and a half times. The Aim of the workis to assess the real probability of exceeding the impact level when calculating the seismic resistance of buildings and structures. Research methods - analysis of procedures for assessing calculated impacts using SRF maps and building codes. Results of the work - it is shown that the standard level of accelerations in the calculations of seismic resistance is more than twice lower than the real values.

Potential Key Factors, Policies, and Barriers for Rooftop Agriculture in EU Cities: Barcelona, Berlin, Bologna, and Paris

The main objective of this study is to contribute a framework and to provide an overview of potential key factors, policies, and barriers associated with the integration of rooftop urban agriculture (RUA), building on stakeholders' perspectives in four European cities (Barcelona, Berlin, Bologna, and Paris). The research was developed in two phases, namely, a workshop and a survey of stakeholders involved in RUA from the four cities. Education, environmental, research, technological innovation, food production, and social factors play an important role in implementing RUA. Productive spaces, cultural values, social cohesion, social rural-urban links, and the high cost of urban land are highlighted as factors that “promote” RUA. In contrast, the cost of water and pollution are major contextual factors that constrain RUA. Policies related to food trade and urban planning are those that most limit RUA development. Major architectural and technical barriers related to the limits on building heights, historical buildings, a lack of specific building codes, building design and roof accessibility were identified. The high cost of infrastructure and policies that prohibit RUA product sales emerged as economic constraints. Major differences among the cities studied included the perceived effect of urban policies on RUA diffusion as well as the perceived relevance of economic and pollution factors. This study revealed that extensive dissemination and the development of appropriate information about RUA are needed. The creation of new regulations, as well as modifications to urban and building codes to support RUA, is also envisaged. This approach will consider a more flexible land-use policy that allows agriculture to take place in cities as well as marketing frameworks for RUA products. For future studies, it would be useful to apply the framework developed in this study to a larger sample. A study is also needed to confirm hypothetical differences between cities.