Concrete Floor Slabs Research Articles

Model Perkuatan Anyaman Bambu pada Subgrade Bungker Tangki Pendam

A submersion tank bunker is a storage place for fuel oil tanks at public fueling stations (gas stations). Its function is to localize oil splatters so as not to pollute the soil below if there is a leak in the oil tank. The construction of the submersion tank bunker at the Kelapa Gading gas station in North Jakarta, the basic soil condition is muddy due to low groundwater. This condition is improved by applying a covering layer of bamboo mattress. Bamboo mats are made from wormwood bamboo (Gigantochloa Apus) which is split 5 cm wide each sheet, and then woven to form a woven grid. The presence of groundwater at the bottom of the excavation, drained by pumping out (dewatering). After laying sand, the next step can be casting the bunker concrete floor slab. It is proven that woven bamboo in the form of bamboo mattresses is an alternative to basic soil improvement that can increase the carrying capacity of basic soil effectively.

RESULTS OF THE TECHNICAL INSPECTION OF A MULTI-STORY RESIDENTIAL BUILDING DAMAGED AS A RESULT OF A ROCKET IMPACT

The article presents the results of the examination of the technical condition of part of the construction structures of the building damaged as a result of a missile strike, the determination of the characteristics and classification of their defects and damage, the provision of conclusions and recommendations regarding the correction of the life cycle and further safe and reliable operation of the building. As part of the study, the object of the survey was a monolithic 22-story residential building with a basement (ATP) floor and a complex configuration in plan. The structural scheme of the complex is a monolithic reinforced concrete frame with stiffening cores. The stability and rigidity of the frame is ensured by diaphragms of stiffness in the form of reinforced concrete walls, elevator-stair nodes and rigid nodes connecting pylons and horizontal disks of monolithic reinforced concrete floor slabs. During the examination, visual and instrumental methods of research were performed. Before the field work, measures were taken to collect design and archival information about the research object. Instrumental studies to determine the actual concrete strength of reinforced concrete frame elements and to determine the diameter, protective layer and pitch of the working rods of the reinforcing frames of the load-bearing elements were carried out by non-destructive methods. The calculation model of the spatial scheme of the structure of the frame of the residential building, taking into account the damage, was made in the subsystem (PS) "COMPOSITION" of the software complex (PC) "MONOMAH CAD". The result of the survey is conclusions and recommendations, which indicate the specifics of damage and types of defects, destruction and debris in various structural elements that were discovered during the survey. The general technical condition of the residential building is classified as emergency. As for the recommendations, two options for carrying out repair and restoration works were provided. The first option is to restore the plan-elevation position of the building, the design marks of vertical and horizontal structures and the unloading of overloaded structures, to be performed with the help of an automatic hydraulic complex. The second option is the arrangement of temporary strengthening of emergency structures with the help of a metal space frame, without restoring the planned height position of the residential building.

Identifying the evolution of through cracks in iron-reinforced hollow slabs under the influence of a standard fire temperature mode

The object of this study is the fire resistance of reinforced concrete hollow slabs at the onset of the limit state of loss of integrity. The problem of accurate modeling of the formation and development of cracks in concrete was investigated. The paper reports an analysis of the results of the stress-strain state of a reinforced concrete hollow slab during fire exposure for devising a method for evaluating the fire resistance of such structures upon the onset of the limit state of loss of integrity. According to EN 1992-1-2, the determination of fire resistance of structures is provided by calculation methods, however, there is no such procedure for reinforced concrete hollow slabs. Many scientific works offer refined methods for evaluating only the loss of load-bearing and heat-insulating capabilities, leaving aside the issue of loss of integrity. Thus, this can lead to a biased evaluation of reinforced concrete hollow floor slabs according to the criterion of the limit state of loss of integrity, which in turn can put under a threat to the fire safety of buildings, which threatens the life and health of people. According to the results of the calculation, a parameter has been determined, according to which the onset of the limit state of fire resistance, in particular, the loss of integrity, was established. Summarizing the damage distributions, it was assumed that in the case of reaching the critical plastic deformation of 2.5e-3 in concrete finite elements, they are excluded from the general set of finite elements. Thus, in the case of the formation of through cracks, the removal of finite elements is taken as a parameter to identify the onset of the limit state of loss of integrity. According to the results of the computational experiment, it was established that through cracks in a fragment of a reinforced concrete hollow slab are formed in 44 min. According to the results of the research, the method of evaluating the fire resistance of such structures based on the onset of the limit state of loss of integrity has been substantiated. Such a method could be applied during design, which provides an opportunity to determine the limit of fire resistance in reinforced concrete hollow slabs

Optimizing the Location of Supports under a Monolithic Floor Slab

Monolithic reinforced concrete floor slabs are one of the most common types of building structures, and their optimization is an urgent task. The article presents the methodology for finding the optimal position of point supports under a reinforced concrete floor slab of arbitrary configuration at arbitrary load. The slab is considered thin, elastic and isotropic, with constant over-the-area stiffness, that is, the reinforcement is not taken into account or is constant. The solution is performed using the finite element method in combination with the nonlinear optimization methods. Finite element analysis is implemented by authors in MATLAB (R2024a) environment in such a way that the location of the columns may not coincide with the nodes of the finite element mesh of the slab. This allows to significantly increase the efficiency of solving the optimization problem compared to previously used algorithms, including the Monte Carlo method. Boundary conditions are taken into account using the Lagrange multiplier method. As an optimization criterion, the maximum deflection value is used, as well as the value of the potential strain energy. The effectiveness of six nonlinear optimization methods is compared in the example of a square slab under the action of a uniformly distributed load. For solutions obtained using the pattern search, simulated annealing and internal point methods, the maximum deflections are at least 1.2 times higher than for solutions obtained using the particle swarm method and genetic algorithm. An example of real object optimization is also presented. By changing the position of seven columns, it was possible to reduce the maximum deflection of the floor slab by 1.6 times.

Vibration response of ultra-shallow floor beam (USFB) composite floors

This paper examines the vibration response of the steel-concrete composite Ultra Shallow Floor Beam (USFB®) flooring system which incorporates asymmetric steel perforated beams to accommodate the concrete floor slab within the depth of the flanges while allowing reinforcement and/or service ducts to pass through the web openings. This is a lightweight flooring system that can accommodate long spans, thus becoming susceptible to floor vibrations due to external resonant dynamic loads. To investigate the influence of slab thickness and boundary conditions on the natural frequencies of the USFB flooring system, parametric studies are conducted using a finite element model and five floor spans. The model was first validated against an experimental test conducted by the authors. Emphasis is placed on the fundamental frequency to predict the possibility of resonance of this complex flooring system with typical human-induced dynamic loads in building structures. To further facilitate the practical numerical modelling and vibration analysis of buildings with USFB floors in standard commercial structural software, an analytical method of deriving equivalent isotropic plate properties is developed and its accuracy is numerically verified vis-à-vis with detailed ABAQUS models.

The effect of non-removable void generators on the strength of monolithic reinforced concrete floor slabs clamped along the contour

The article presents the results of a numerical experiment to determine the effect of non-removable void generators on the strength of monolithic reinforced concrete floor slabs clamped along the contour. The experimental samples are made in the form of spatial models using volumetric finite element models in the LIRA-CAD software package. The tests were carried out on 4 series of samples, differing in terms of dimensions and reinforcement. Detailed descriptions of the dependencies used and the laws of deformation of materials during the construction of models are given. The values of compressive stresses in concrete and reinforcement, as well as tensile stresses in reinforcement obtained as a result of tests, were subjected to comparative analysis. Based on the conducted experiment, it was found that the use of non-removable voids in a monolithic reinforced concrete slab does not reduce its strength, while reducing concrete consumption by 18.3-23.1%.

Research on carbon emissions during the construction process of prefabricated buildings based on BIM and LCA

ABSTRACT The goal of double carbon reflects the new goals and requirements of China’s entry into a new development stage. In this regard, the construction industry, as a large producer of carbon emissions, should focus on emission reduction. In the whole life cycle of buildings, the carbon emission intensity in the physicochemical stage is the largest, so we should focus on the carbon emission in the physicochemical stage. Compared with the cast-in-situ concrete floor slab, the bidirectional prestressed precast hollow slab (BPPHS) has the characteristics of environment-friendly under the condition of meeting the building stress, and the manufacturing process of precast floor slab is more standardized, which can give full play to the performance of components. Based on BIM (Building Information Modeling) and LCA (Life Cycle Assessment) theory, and in the case of tram transportation, this paper studies the carbon emission of prefabricated hollow floor slab used in prefabricated buildings in the building stage. The research shows that the use of BPPHS reduces the carbon emission of 197,332.81 kg in the whole physicochemical stage, and the emission reduction rate is 46.52% compared with the cast-in-place slab. Compared with the ordinary prefabricated laminated plate, the emission reduction rate reaches 45.40%; The carbon emission sources in the materialization stage of prefabricated buildings are divided into production stage, transportation stage and construction stage. The carbon emission reduction in each stage accounts for 42.29%, 46.18% and 51.08%, respectively, in each stage of cast-in-situ floor slab. Compared with ordinary precast slab, the emission reduction rates of each stage are 34.67%, 53.60% and 47.84%, respectively. The emission reduction potential of BPPHS is very considerable. It can not only promote the development of prefabricated buildings but also have lower carbon than conventional precast slab. The study provides new ideas for reducing building carbon emissions, which will also provide reference for industry entrepreneurs and relevant governments to realize low-carbon economy and sustainable development.

Physical-Model-Based Assessment of Reduction of Hydraulic Forces Acting on Channel Bed through Advanced Energy Dissipator Design

The hydraulic engineering designers focus on shaping up the flow regime so that the greatest energy dissipation is ensured. On the other hand, the structural designers focus on load bearing capacity and durability of the structural components which may contradict the focus of the hydraulic experts. Such a case may occur when the spillway chute floor slab must be thin due to the limited spaces. Then, the dynamic load acting on the chute floor slab may compromise its long-term operation. The dynamic forces are created by the violent turbulences which may even coincide with the natural frequency of the reinforced concrete floor slab. Therefore, the objective of this paper is a complex approach to small-scale physical model testing which makes use of the latest rapid-prototyping techniques and the particle image velocimetry, and which in the end allows to estimate the magnitude of the dynamic hydraulic forces acting on the channel bed. The newly developed organic-shape energy dissipators play a key role in reducing the kinetic energy of water through its enhances aeration. The proposed method on a small scale can assist favorably the design process of real-scale hydraulic reinforced concrete structures.

GEODETIC MONITORING OF DEFORMATIONS OF BEARING REINFORCED CONCRETE STRUCTURES OF AN UNDERGROUND MULTI-FUNCTIONAL PUBLIC CENTER

The article highlights the stages of carrying out measurement and survey work of an underground multifunctional public center to assess the technical condition of the load-bearing structural elements of block 1 and the entrance group in order to carry out reconstruction on the above-ground part of the building. The reconstruction consisted of installing metal structures on the eastern and western sides of the dome and a metal canopy over the entrance group. As a result of a technical examination and geodetic observations, cracks with an opening width of 0.5 mm and significant deflections in the floor slabs and crossbars at the upper and lower levels were identified in the load-bearing structures. To ensure safe operation and timely detection of dangerous values of deformation of a unique building with an increased class of responsibility, an effective method of geodetic monitoring of deflections of reinforced concrete floor slabs and crossbars and recommendations for their strengthening, taking into account the location of the construction site at the intersection of zones of influence of several tectonic faults, are proposed. Geodetic observations of deformation processes were carried out. Based on the results of the measurements, it was decided to strengthen the reinforced concrete structures by gluing fiber-reinforced composite materials to the lower part of the floor slabs. A comparative analysis of the obtained quantitative parameters of shifts of load-bearing structures makes it possible to assess the technical condition of an underground building and its individual structures before and after strengthening measures.

Onsite and laboratory assessment of repair mortars for reinforced concrete floor slabs in heritage buildings

The conservation and repair of XX century architectural heritage built with reinforced concrete is becoming more and more important and requires suitable materials and technical solutions. In particular, effectiveness, compatibility and durability must be ensured, in spite of the limited extent of demolition allowed by the local authorities, and the literature in this field is still limited. In this paper, an experimental campaign was carried out in an historic reinforced concrete floor slab, where different repair mortars were used. After some on-site testing on the corrosion potential, the concrete beams of the slab were integrally cut and transported to the laboratory for a series of systematic tests, aimed at investigating the performance and compatibility of the repair materials, as well as any possible issues hindering the success of this structural intervention. The filling ability, physical compatibility, chemical compatibility and mechanical compatibility of the repair mortars and the corrosion behavior of the steel reinforcement were investigated, deriving some results of general interest, which may contribute to a better insight about the repair of heritage concrete floor slabs.

Stress Analysis of Pin Connections in Steel Box Girder with the Unibridge System using Finite Element Model

This study analyzes the Unibridge system, a modular steel box girder employing two pins for longitudinal connections, thereby expediting construction compared to traditional girders. A finite element model was developed to analyze the stress on these pins in a single-box girder with five segments and a reinforced concrete floor slab. Various loads were applied following the Indonesian bridge loading standard, SNI 1725:2016. The model considers operational load analysis and assumes full composite behaviour between the top flanges of the girder and the concrete floor slab. The results indicate that the Von-Mises stress on the pins reaches a maximum of 490.95 MPa under combined service loads, consistently remaining below the specified material yield stress limit of 1200 MPa. Consequently, the Demand Capacity Ratio (DCR) is 0.41. As a result, the Unibridge girder connection pins do not experience plastic deformation under the applied loads.

Coefficients of the irregularity of the deformation of the reinforcement and the concrete of corrosion damaged reinforced concrete slabs

Introduction. In practice, to perform calculations to determine the bearing capacity of reinforced concrete slabs at the stage of cracking, the work of concrete between cracks in the tension zone is taken into account.
 
 This paper presents the results of full-scale tests of damaged precast reinforced concrete floor slabs to determine the coefficients V.I. Murashev – uneven deformations of reinforcement ψs in the tension zone and concrete ψb in the compression zone for corrosion-damaged slabs in the stage of cracking.
 
 The aim of the work: to determine the coefficients of uneven deformation of reinforcement and concrete experimentally for corrosion damaged reinforced concrete floors at the stage of cracking.
 
 Materials and methods. The article describes the methodology for setting up an experiment to measure the deformations of reinforcement and concrete, slab deflections, crack opening widths, and describes the parameters of the testing installations.
 
 Results. The work presents the main results of experimental studies in graphical form.
 
 Conclusions. Research shows that with the appearance of cracks, the coefficient ψsx first increases and then stabilizes. The coefficient ψbx immediately after the formation of cracks first increases slightly, then decreases more gradually.

CONSTRUCTIVE SOLUTIONS FOR EXPLOSION-RESISTANT BUILDINGS WITH CIVIL PROTECTION FACILITIES

In the conditions of the large-scale war led by russia in Ukraine, the issue of designingblast-resistant buildings with civil defense facilities that can withstand additional special loads and impacts has become crucial. These impacts include artillery and missile attacks, bomb explosions, blast waves, and the spread of fires, among others. An analysis of the consequences of building and structure destruction resulting from military operationsindicates that reinforced concrete structures of buildings have superior load-bearing capacity compared to traditional brick and steel frames of pavilion-type buildings.Reinforced concrete is a non-combustible material with significant mass, improving its inertialresistance. It possesses high strength and plasticity characteristics, allowing it to deform and redistribute forces between adjacent structures, thereby preventing progressive collapse – the cascading destruction of buildings.The main principles of designing blast-resistant reinforced concrete frames for high-rise buildings involve rational constructive systems and schemes with simple and compact configurations and symmetrical plans. The structural solution of the reinforced concrete frame must ensure the redistribution of gravity loads between adjacent structures. Therefore, the joints of vertical and horizontal structures must be plastic, capable of dissipating a significant amount of explosion energy. The load-bearing elements of buildingstructures must withstand cycles of large deformations in different directions, such aspressures from the lifting of floor slabs opposing ordinary gravity loads. For buildings classified with medium (CC2) and significant (CC3) consequences, where more than 50 individuals are constantly present or periodically more than 100 people, it is necessary to design civil protection premises. These premises should be strategically located below the planned ground level.The construction of civil protection premises located in the underground floors of an explosionproof building must withstand all types of main and episodic loads and impacts and resist the spread of fire. Building frames with monolithic reinforced concrete ribbed ceilings and systems of main and secondary beams or transversely located beams rigidly fixed to vertical supporting structures – columns, pylons, walls – can withstand such loadsbest. The article investigates the reasons for the destruction of reinforced concrete slabs in high-rise frame monolithic buildings when subjected to bending or pressure from explosive loads below. It also explores the potential twisting of the building as a result of reverse explosive effects.The article presents measures to strengthen sections of floor structures in high-rise framemonolithic buildings that may be destroyed due to reverse explosive loads and upward pressure from explosive forces. The expediency of reinforcing critical areas of monolithic reinforced concrete floor slabs with external reinforcement – adhering reinforcing mats in the form of fabrics, lamellas, or carbon fiber nets to the upper zones of slabs near vertical supports – is justified.

Equations for early-stage design embodied carbon estimation for concrete floors of varying loading and strength

Building designers are increasingly tasked with tracking and reducing the embodied carbon of structural systems, including concrete floor slabs. Design decisions that affect both the structural performance and the embodied carbon of a concrete floor are often made in the early design stages without complete structural analyses and life cycle assessments, which are commonly finalized in later stages. In this study, we employ polynomial regression models to estimate the embodied carbon for ten concrete floors to guide practitioners toward environmentally-informed design decisions. Six reinforced concrete (RC) and four post-tensioned (PT) floors are evaluated with varying five structural parameters including the span length, concrete strength, live and dead loads, and deflection limit, equating to 41,328 design scenarios for the RC systems and 27,552 design scenarios for the PT systems, while also considering 32,440 different concrete mix Environmental Product Declarations. The analytical equations are deployed in a web-app intended for practitioners to quickly evaluate and compare different design scenarios and floors. By estimating the embodied carbon of concrete floors while accounting for design and material uncertainty, these equations are ready for immediate use to reduce the carbon footprint of future buildings.

Оценка несущей способности железобетонной плиты пола цеха на армированном грунтовом основании

A method for calculating the floor structure of an industrial building on a compensatory soil cushion on a base reinforced with vertical elements is considered. The foundation is composed of weak soils and reinforced with driven reinforced concrete piles. The compensation cushion is made of sandy soils compacted to the required deformation modulus. The calculation was performed using the numerical method in the SCAD software package. Information was obtained on the stress-strain state of piles, pad soil and floor slab. The soil of the compensation cushion was tested to meet the strength conditions of A.I. Botkin. The possibility of using a reinforced concrete floor slab of an industrial building has been determined.

Experimental Determination of the Bearing Capacity of a Reinforced Concrete Floor Slab

Purpose of research. Experimental determination and analysis of the bearing capacity, deformability and crack resistance of a reinforced concrete floor slab supported on three sidesMethods. Testing a specimen of a reinforced concrete floor slab supported on three sides (loggia floor) by a controlled load simulating the operational one. Measurement of deflections. Analysis and justification of test resultsResults. The slab was loaded to a level of 325 kN or 20.1 kPa. This load exceeded the control load by a factor of 1.64 with a safety factor of 1.6, exceeded the design load by a factor of 2.64, and exceeded the standard load by a factor of 3.08. The maximum recorded deflection at maximum load was 3.01 mm in or in span fractions of 0.0009, which is 7.41 times less than the allowable deflection from the standard load - 0.00667 of the span length. The testing has been terminated for safety reasons.Conclusion. The points that could allow the developing of more economical building structures are: refinement of the design scheme for the operation of structures, the optimal choice of a finite element in the calculation, as well as the gradual inclusion in the sets of rules of methods for calculating building structures based on the theory of structural systems with distributed parameters at critical energy levels.

Moisture transport properties of concrete with SCMs – descriptions, test methods and some applications

AbstractMoisture transport properties of concrete are rarely determined, simply because it is difficult and time‐consuming. Most studies in literature are limited to cement paste and mortar. Translation of these properties to concrete are not straight‐forward. Recently, however, a few measurements are done, also on concretes with supplementary cementitious materials.An overview is given on various ways of theoretically describing the moisture transport properties of concrete, with different “moisture transport coefficients” and their interrelations. Methods of determining those properties are shown and their advantages and drawbacks are discussed. Available data in literature are summarized and compared. A recently developed test method, the tin‐can method, is described. New results are shown for concretes with SCMs. The method's possibilities to be used for short‐term tests of aging concrete are discussed.A few important applications where the moisture transport properties are decisive are presented: applying moisture‐sensitive flooring materials on concrete floor slabs and carbonation‐initiated reinforcement corrosion under varying climatic conditions.

Influence of the Structural Support Model on the Stress-Strain State of Reinforced Concrete Floor Slabs

The influence of modeling the support of floor slabs on forces and deformations is shown. In slabs freely supported on the walls, the corner zones move upwards. In slabs that are partially pinched into the walls, negative bending moments occur. The degree of pinching and separation of the corner zones depends on several factors. The article shows how to take into account these factors in the design.

UJI BEBAN PADA STRUKTUR BANGUNAN CAGAR BUDAYA JEMBATAN LOJI KOTA PEKALONGAN

The Loji Bridge in Pekalongan City is a cultural heritage building that was built in 1880, during the Dutch East Indies colonial period. The Loji Bridge is more than 150 years old and is still standing and is only used for bicycle and motorbike traffic. When it was built, it was an important bridge because it was a bridge on the north coast road. Until now, this has been the way of the economy. The condition of the bridge is currently unknown as to its structural feasibility. The Pekalongan city government will revitalize the bridge left over from the Dutch era so that it can be used again. If it is not possible for traffic to be used, it will be used as a place for MSME activities. So in the city of Pekalongan there are interesting places to attract visitors as culinary tourism spots and others.To determine the suitability of the bridge structure with a span of 50 meters, testing needs to be carried out. The test carried out is a load test. Why is a loading test carried out because there is no bridge building data, superstructure data or substructure/foundation data. So with a loading test you can immediately determine the amount of load the bridge can safely withstand.The loading method uses water loads, namely by creating a loading pool. The load is adjusted to the planned traffic load / live load. The equipment installed and recorded during the test is to determine and monitor the bridge settlement, either in the pillars or beams. Monitoring is carried out to maintain deflection / settlement. So that the decrease / deflection that occurs during testing is still within safe limits.The equipment used to monitor and record deflection is a Linear Variable Displacement Transducer (LVDT) which is connected to a data logger and computer. The LVDT is placed on wooden stakes / poles stuck into the river bed, so that the readings decrease relative to the river bed.Loji Bridge with a span of 50 meters consists of 4 pillars and 2 abutments. Upper structure with asphalt pavement, wooden plank floor. The abutments use river stone pairs and the pillars use 7 solid pipes with a diameter of 12 cm. Later, it is planned to replace the wooden floor with a reinforced concrete slab floor on the bridge.

Resilient performance of steel connections with low yield point fuses considering the effect of RC floor slab

The beam-column connection of a steel frame equipped with replaceable low yield point steel cover plates (SF-LYCP) was proposed to address the significant repair challenge and financial losses caused by beam-column connection brittle failure after an earthquake. According to an experimental study, the SF-LYCP exhibited outstanding bearing capacity, ductility, energy dissipation, and post-earthquake rapid recovery performance. To explore the effect of the reinforced concrete (RC) floor slab on the mechanical behavior of SF-LYCP in a natural working environment, the finite element method of steel beam-column connection with low yield point (LYP) steel cover plates considering the effect of the RC floor slab (SF-LYCP-RCslab) was developed and analyzed by ABAQUS. The results demonstrated that the proposed finite method was able to accurately predict the behavior of SF-LYCP-RCslab. The load capacity, initial stiffness, and energy dissipation capacity of the SF-LYCP-RCslab were increased in comparison to the SF-LYCP. The LYP cover plates in the SF-LYCP-RCslab still played the desirable role of structural fuses. However, the concrete of the RC floor slab had severe damage and prevented the quick replacement of repairable LYP cover plates. Based on these findings, four improved strategies for the SF-LYCP-RCslab were proposed to reduce concrete damage and increase the replacement convenience of damaged elements. Comprehensively considering the bearing capacity, ductility, energy dissipation, structural fuse function, concrete damage, and post-earthquake rapid recovery performance, the improved strategy, which adopted a profiled steel–concrete composite floor slab with a gap, was recommended in steel frame beam-column connection design.