Roof Load Research Articles

Equation Development for Calculating Loads Acting under the Antenna Tubular Mast Supports of Cellular Communication Equipment

A study presents the search for the relationship between the composition of the antenna equipment of the base cellular station, taking into account the height of its suspension and the load on the roof under the supports of the designed structures of antenna tubular masts mounted on buildingroofs. New telecommunications standards aimed at improving quality and speed of wireless communications and the Internet involve thickening the existing network and increasing the number of base cellular stations. In cities with high population density and dense buildings, antenna tubular masts on buildingroofs are designed to accommodate antenna equipment. The location selection for structure mounting is carried out in the course of surveys involving the mobile operator, the construction organization and the landlordcooperation. The design organization performs a verification calculation of the load capacitydue to the need of roofload-bearing building structure check for the possibility tomount tubular masts, in each specific case. In case of a negative conclusion, repeated surveys and approval of the newly selected position are required. The equation derived during the study is proposed, using the initial data contained in the design specification, visual inspection and design documentation for the building, allows determination of load magnitudes under the support of the designed structure and evaluation the possibility of tubular mast mounting before performing calculations by means of software complexes. To develop the equation to determine the relation between payload factors acting on antenna equipment and the roof loads of a building under a loaded tubular mast support, the method of correlation and regression analysis was used. The results of the study will improve the surveyefficiency, which will minimize the risks of inconsistencies and reduce the time spent on design.

Deformation and Fracture Mechanisms of Thick Hard Roofs in Upward Mining Coalfaces: A Mechanical Model and Its Validation

The safety and efficiency of underground coal mining are threatened by thick hard roofs characterized by large overhang areas, problematic spontaneous caving, and high dynamic load upon their breakage. In this study, a mechanical model of the bearing capacity of thick hard roofs in upward mining coalfaces associated with mining activities is built based on bending theories for beams with single generalized displacement and the elastic foundation beam theory. Using this method, we analyze the deformation and fracture mechanisms of a thick hard roof during upward mining. We further derive the mechanical equations of rotational angle, bending moment, shear force, and deflection of the free overhang and coal-bearing zone in the thick hard roof and an equation for calculating the limiting span. The mechanical behaviors of the thick hard roof bearing state are analyzed under different parameters. The results show that the foundation coefficient, roof thickness, and angle of upward mining have little influence on the roof bending moment but are positively correlated to the limiting span. Roof load and overhang length have a significant influence on the roof bending moment. They are negatively and positively correlated with the limiting span, respectively. Finally, a case study is performed on the Ш601 upward mining coalface in the Zhuzhuang Coal Mine. The distribution characteristics of the bending moment of the thick hard roof at different extraction stages are analyzed. At each stage, the limiting spans of the thick hard roof upon breaking were calculated as 13.18, 18.82, and 22.50 m, respectively, being close to the on-site measured periodic weighting lengths of 13.33, 19.33 m, and 22.67 m. This close fit proves the feasibility and accuracy of the developed mechanical model. The present study offers theoretical guidance for estimating the weighting length of thick hard roofs in coalfaces and for engineering technology control in similar scenarios.

Superhydrophobic foamed concrete based on response surface method: Mix design and its potential application in roofing systems

Superhydrophobic foamed concrete based on response surface method: Mix design and its potential application in roofing systems

Deformation ability of modular gymnasium steel inner sleeve all-bolt cross connection joint based on 3D-DIC method

Deformation ability of modular gymnasium steel inner sleeve all-bolt cross connection joint based on 3D-DIC method

Determining patterns of the vertical load on a covered wagon roof with a frame in the form of a triangular arch

The object of this paper is the processes of perception and redistribution of loads in the roof of a railroad covered wagon with a frame in the form of a triangular arch. To reduce the tare of the covered wagon, it is proposed to improve the structure of its roof. A feature of this improvement is that the roof frame is made in the form of a triangular arch with a reinforcing belt. This contributes to the reduction of the total mass of the roof compared to a typical structure. The selection of execution profiles of the beams forming the arch is carried out according to the maximum values of the moments that act in their cross-section. Taking into account the chosen profile of the arches, the calculation of the strength of the roof when it receives vertical loads was carried out. It was established that the strength of the roof under the considered load schemes is within the permissible stress values. Since the improvement of the roof structure contributes to the reduction of its weight by 1.8 % compared to the prototype, the movement of the covered wagon was evaluated under conditions of moving while empty. To this end, a mathematical modeling of the load of the covered wagon in the vertical plane during its movement along the joint unevenness was carried out. On the basis of the performed calculation, it was established that the movement of the wagon is assessed as "good". Special feature of the results is that the reduction of the tare of the supporting structure of the wagon was achieved by improving its roof, as the least loaded unit. The field of practical application of the results is railroad transport, including other areas of mechanical engineering. The conditions for the practical use of the results are a symmetrical roof load scheme in operation. The results of this research could contribute to advancements related to the design of modern structures of freight wagons with improved technical and economic indicators

Damage analysis and mechanical performance evaluation of frame structures in recycling

Damage analysis and mechanical performance evaluation of frame structures in recycling

Seismic analyses of single-layer dome structures with random geometrical imperfections under stochastic ground motions

Seismic analyses of single-layer dome structures with random geometrical imperfections under stochastic ground motions

Industrial Building Structure Planning With Cranes

Industrial building structure planning complies with standards and regulations, such as Procedures for Earthquake Resistance Planning, Minimum Loads for Building Design, and Specifications for Structural Steel Buildings. Vertical and lateral loads are fundamental to the structure's load flow process. Industrial buildings handle roof, wind, earthquakes, crane, and wall loads. Structural design must consider these elements, including the choice of lateral force-resisting systems such as X-bracing. In determining building loads, including earthquake and wind loads, various parameters such as wind speed, exposure category, and other factors must be considered by standard requirements such as SNI 1727-2020 and SNI 1726:2019. Selection of site class, wind direction, topographic, and ground surface elevation factors are essential in determining wind loads. This research method focuses on supporting structures consisting of purlins and girts in the context of industrial buildings. Purlins, made from hot or cold rolled steel, generally use C and Z profiles. Girts, made from cold or hot rolled steel, have profile variations such as C, Z, or hollow square sections. The girt structure design process determines dimensions, rod sag, internal requirements, and sag rod capacity.

Deformation Analysis of Desalinated Water Storage Tank Using Finite Element Method

Deformation in a structure is something that is very likely to occur when the object is subjected to a loading that leads to a pressure on the object. The approach taken to determine the deformation of the cylindrical tank was carried out using the finite element method using Ansys 2020 R2 software with axial loads due to the roof and circumferential loads on the cylinder from wind forces. The cylindrical tank that was the object observed in the practical work field was found to be deformed due to the very high loading from the roof and also the result of re-welding due to the repair of defective welds after being examined by ultrasonic testing. This was investigated using the finite element method to determine if the loading experienced by the cylinder was the main cause of the deformation and it was found that the maximum deformation was so small that it was difficult to say that the main cause of the deformation was the loading. It is known that re-welding a metal will change the mechanical properties of the material to become softer, which is the main reason why the deformation of the tank occurred in the practical field.

Mechanical performance study of a novel modular gymnasium inner sleeve all-bolt cross connection joint – part Ⅰ: Experiments and finite element modeling

Mechanical performance study of a novel modular gymnasium inner sleeve all-bolt cross connection joint – part Ⅰ: Experiments and finite element modeling

Experimental and numerical simulation study of mechanical properties of inner sleeve T-joint in modular gymnasia

Experimental and numerical simulation study of mechanical properties of inner sleeve T-joint in modular gymnasia

Stability Analysis and Control Methods of a Layered Roof of Gob-Side Entry in Inclined Rock Strata.

In view of the instability of a layered roof of the gob-side entry in inclined rock strata, with the engineering background of the gob-side entry with a small-width coal pillar in Xutuan Mine, the deformation and failure characteristics of the layered roof and the control measures in inclined rock strata are studied by comprehensively adopting field investigation, numerical calculation, theoretical analysis, and engineering tests. The results show the following. (1) After the instability of the layered roof, an unstable zone, a substable zone, and a stable zone are formed accordingly in the surrounding rock from shallow to deep. The unstable zone is an active area in terms of roof deformation and is the main object in the surrounding rock control. The substable zone has a macro control effect on roof deformation. The stable zone is the main bearing structure of the roof. (2) The rock structure has a significant regulatory effect on roof deformation and damage. As the thickness of the layers increases, the bearing capacity of each layer increases and the overall strength of the roof increases. At the same time, the influence range of the substable zone increases, which has a restraining effect on the expansion of the unstable zone. (3) The maximum deformation of the roof decreases exponentially with the increase in thickness of the roof rock beam, increases linearly with the increase in lateral pressure and roof load, and increases exponentially with the increase in entry span. (4) Based on the "two enhancements and one weakening" surrounding rock control strategy, a support system with "high-strength bolts and cables, shotcrete, and anchor grouting" as the core is proposed. The results of field tests indicate that the designed support scheme effectively controls the deformation of the layered roof and achieves long-term stability of the gob-side entry with a small-width coal pillar.

Stability control of overburden and coal pillars in the gob-side entry under dynamic pressure

Stability control of overburden and coal pillars in the gob-side entry under dynamic pressure

Study on Failure Mechanism and Support Design of Tunnel Surrounding Rock

Taking a tunnel as the engineering background, this paper focuses on the mechanism of large deformation of soft rock, the design and optimization of supporting technology, aiming at the problem of large deformation of tunnel surrounding rock. By means of numerical simulation, the failure mechanism of structural large deformation of layered surrounding rock is deeply analyzed and studied. The tunnel is simulated with different support parameters to find more reasonable support parameters and optimize the existing support. The results show that the displacement of surrounding rock increases with the increase of upper load. When the roof load is less than 0.7 MPa, the vertical displacement of the sensitive block tends to be stable after a certain period of time; When the top plate load is 0.7 MPa, the vertical displacement of the roof sensitive block cannot converge, so some reinforcement measures must be taken at this time. When the tunnel is supported by bolts, the longer the length of bolts, the better the effect will be. 3m anchor length should be selected for support, and other support methods should be added to control tunnel deformation.

Management strategies for maximizing the ecohydrological benefits of multilayer blue-green roofs in mediterranean urban areas

Multilayer Blue-Green Roofs are powerful nature-based solutions that can contribute to the creation of smart and resilient cities. These tools combine the retention capacity of traditional green roofs with the water storage of a rainwater harvesting tank. The additional storage layer enables to accumulate the rainwater percolating from the soil layer, that, if properly treated, can be reused for domestic purposes. Here, we explore the behavior of a Multilayer Blue-Green Roof prototype installed in Cagliari (Italy) in 2019, that have been equipped with a remotely controlled gate to regulate the storage capacity of the system. The gate installation allows to manage the Multilayer Blue-Green Roof in order to increase the flood mitigation capacity, minimizing the water stress for vegetation and limiting the roof load with adequate management practices. In this work, 10 rules for the management of the Multilayer Blue-Green Roof gate have been investigated and their performances in achieving different management goals (i.e., mitigating urban flood, increasing water storage and limiting roof load on the building) have been evaluated, with the aim to identify the most efficient approach to maximize the benefits of this nature based solution. An ecohydrological model have been calibrated based on field measurements carried out for 6 months. The model has been used to simulate the system performance in achieving the proposed goals, using as input nowdays and future rainfall and temperature time series. The analysis reveled the importance of the correct management of the gate, highthing how choosing and applying a specific management rule helps increasing the performance in reaching the desired goal.

Pengkinian Konstruksi Joglo Tanpa Empat Saka Guru

Title: Updating Joglo Construction Without Four Saka guru (Case Study of Pendopo Pura Agung Blambangan of Banyuwangi) Current architectural developments to maintain its sustainability have reached the awareness stage to explore the potential for the diversity of archipelago architecture, one of which is exploring the potential for the Joglo traditional house for the future. The demand for wide spans often comes to the fore, so it is not uncommon for new construction designs to respond to the demands for wide spans free from pillars. However, a solution is needed to solve this problem. The pillars and their frames are the main part of the main reinforcement system for the roof load as a whole, so they become prerequisites on behalf of the Joglo. This writing aims to analyze the updated form of construction without pillars that still maintain the Joglo form. The research method uses a qualitative descriptive approach by examining the process of eliminating the four pillars of teachers by analyzing the reliability of the structural system of the Puri Agung Blambangan pavilion and the Sabha Swagata Blambangan pavilion in Banyuwangi, East Java. The research results show how the construction of the four pillars and their frames are believed to be the main strength to withstand the roof’s weight. The construction system without the four pillars of the guru and their frames reduces the rigidity of the building because the strength is transferred to the pillars on the edges of the building and does not reflect the joglo structural and construction system. Many knot points have appeared without the pillars and the framework of a construction system, increasing the risk of collapse.

Failure Mechanism and Stability Control of Soft Roof in Advance Support Section of Mining Face

There is a great risk of roof falls in the advance support section of the mining face (ASSoMF), and it is difficult to control the roof. Based on the soft roof of Lijiahao coal mine, this paper studies the stress distribution of the ASSoMF and the space-time evolution of the surrounding rock plastic zone by using theoretical analysis and numerical simulation, and reveals its failure mechanism. Based on the control effect of support resistance on plastic zone, it is proposed that the advance support should mainly adapt to the roadway deformation. Advance equipment without repeated support for mechanized movement has been developed, and the support timing analysis and strength check have been carried out. Results show that the roadway at ASSoMF is in a non-uniform stress field, the confining pressure ratio reaches 1.5~7, and the surrounding rock forms asymmetric failure; the principal stress direction deflects, the angle between it and the vertical direction is about 10°~25°, and the plastic zone of the surrounding rock also rotates to the roadway roof. The proposed equipment can adapt to the characteristics of an unsymmetrical large deformation of a soft roof, and can effectively bear the roof load and maintain the stability of the roadway.

Research on Roof Load Transfer by Passing Coal Pillar of Working Face in Shallow Buried Closely Multiple-Seam

The dynamic load effect of supports is mainly caused by the movement of the roof structure and the load transfer of overburden. In view of the practice issue that the phenomenon of strong ground pressure is easy to happen, when the working face of the lower coal seam passes the inclined coal pillar in shallow buried closely multiple-seam, it will lead to supprot damaged. This paper takes the mining of over-inclined coal pillars in the 22410 working face of the Bulianta Coal Mine as the background, based on the research method combining the field measurement, physical simulation experiment, and numerical calculation, the evolution law of the front abutment pressure (FAP) and roof weighting in mining under the inclined coal pillar is analyzed, and the mechanism of the stress transfer of the inclined coal pillar and the dynamic load of the support is revealed. The research shows that the concentrated stress of the coal pillar is jointly borne by the front coal wall of the working face and the interburden structure above the support. The vertical stress transmitted from the coal pillar to the floor acts on the key blocks of the interburden of the lower coal seam, which causes strong pressure and dynamic load effect, such as roof structure cut-off. The periodic breaking of the key stratum of the interburden leads to the development height and range of the cracks increasing stepwise. The partition characteristics of the mutual transformation of the interburden stress, the FAP, and the working resistance (WR) by passing the coal pillar stage are revealed, which is divided into three stages and four regions. With the working face passing through the inclined coal pillar, the influence area of the concentrated stress of the coal pillar is reduced, and the peak stress of the coal pillar is gradually transferred to the outside of the coal pillar. When the working face is 5 m away from the coal pillar, the peak of FAP and WR reaches the maximum values, the roof is cutting along the peak stress line, and the working face has a strong weighting phenomenon. The research results are consistent with the field measurement results, providing a reference for the mining of working faces under similar conditions.

Optimización de la rigidez equivalente en estructuras de uno y dos pisos sometidas a cargas de techos verdes

Desde una perspectiva lineal y estática, el aumento de los desplazamientos de una estructura debido a la implementación de un techo verde podría ser contrarrestado con el incremento de la rigidez de la estructura. En este artículo se plantea el uso del algoritmo de evolución diferencial para optimizar la rigidez equivalente de una estructura de uno y dos pisos de altura, variando la carga de techo verde bajo el análisis de fuerza horizontal equivalente en la ciudad de Bogotá. A través del software MATLAB se programa y acopla el algoritmo de optimización y la metodología de análisis matricial de estructuras aporticadas tridimensionales sujetas al cumplimiento de la distorsión máxima de piso propuesta por la normativa de construcción colombiana. Un incremento máximo en la rigidez equivalente de 19.25% y 57.80% (estructuras de un piso), y de 11.12% y 32.97% (estructuras de dos pisos) para pesos de techos verdes de 100 kg/m2 y 300 kg/m2 respectivamente, es necesaria para cumplir requerimientos normativos. Se espera que esta investigación sirva como punto de partida para generar soluciones constructivas a la implementación de techos verdes en estructuras de uno y dos pisos en la ciudad de Bogotá.

Investigation of geomechanical properties of tephra relevant to roof loading for application in vulnerability analyses

Tephra fall can lead to significant additional loading on roofs. Understanding the relevant geomechanical properties of tephra is critical when assessing the vulnerability of buildings to tephra fall and designing buildings to withstand tephra loads. Through analysis of published data and new experimental results on dry tephra (both natural samples from Ascension Island, South Atlantic and synthetic tephra made from crushed aggregates), we discuss the geomechanical properties of tephra relevant to roof loading, which include bulk density, grain size distribution and internal angle of friction. Compiled published data for deposits from 64 global eruptions reveal no clear trend in deposit densities based on magma composition or eruption size. The global data show a wide range of values within single eruptions and between eruptions of similar compositions. Published grain size distributions near to source (≤ 10 km) vary widely but again there are no clear trends relating to magma composition. We used laboratory tests to investigate the internal angle of friction, which influences deposit sliding behaviour. For dry tephra, at the low normal stresses likely to be experienced in roof loads (≤ 35 kPa), we found similar values across all our tests (35.8° - 36.5°) suggesting that any internal sliding will be consistent across a variety of deposits. By considering different magma compositions, densities and grain size distributions, we have provided an envelope of values for deposit parameters relevant to roof loading, in which future eruptions are likely to sit. Finally, we created synthetic tephra (fine- and coarse-grained pumice and scoria) by crushing volcanic aggregates and compared it to samples from Ascension and published data. Our results reveal that synthetic tephra successfully replicated the properties relevant to loading, potentially reducing the need to collect and transport natural samples.