by DO THE LIGHT THINGS LIGHT.
Concrete bridges are one of the most common forms of bridges in the world, using reinforced concrete as the main construction material..
It is highly popular due to its strong durability, reliability, flexibility, and economy..
How concrete structure bridges are verified in CDN? In the following serialization, we will provide a detailed introduction to bridge engineers..
The design section will be serialized in three parts: “upper, middle, and lower”. Please continue to follow us.
Important: After the model is successfully imported, the first step is to switch to the appropriate specification, and then the verification items need to be set..
This section contains the items that must be filled in the CDN specification settings.
“3D” (default): Design according to bending, shearing, and twisting components, considering Mz (but not Vy).
“Two dimensional”: designed according to bending and shearing components, without considering torque and Mz.
“Two dimensional+torque”: designed according to bending, shearing, and twisting components, without considering Mz and Vy.
Generally, the default selection for beam verification is “3D”. When conducting shear flexible beam grid or folded beam grid verification, the overall box beam has already been cut open and no longer conforms to the original shear flow. Therefore, according to personal understanding and needs, the impact of torque can be ignored..
Screenshot taken from “Design Specification for Highway Reinforced Concrete and Pre stressed Concrete Bridges and Culverts JTG 3362-2018”.
According to the type of geological exploration environment, the selection will affect the crack width calculation limit of RC components or PSC-B class components..
”Class A components: tensile stress is allowed, but cracks are not allowed for finite values of tensile stress..
Class B components: cracks are allowed, but the crack width is limited..
After selecting the corresponding design component type, the program will retrieve the corresponding formula for crack resistance calculation..
Screenshot taken from “Design Specification for Highway Reinforced Concrete and Pre stressed Concrete Bridges and Culverts JTG 3362-2018”.
The construction methods of “prefabrication” and “cast-in-place” can be selected according to the actual situation..
Screenshot taken from “Design Specification for Highway Reinforced Concrete and Pre stressed Concrete Bridges and Culverts JTG 3362-2018”.
When conducting torsional verification, it is necessary to calculate the torsional reduction coefficient β t. Among them, when calculating Wt, you can check “flange+web” or “web”..
For the box section in the specification JTG 3362-2018, as shown in the following figure, only the torsional resistance moment of the box compartment is considered, which is equivalent to checking the “web plate”;.
Screenshot taken from “Design Specification for Highway Reinforced Concrete and Pre stressed Concrete Bridges and Culverts JTG 3362-2018”.
This section includes calculation methods that can be considered or customizable during verification.
1> Bending resistance calculation – numerical cross-section for design is calculated using any cross-section.
After selecting this option, when checking the bending bearing capacity, the specific values of b and h are no longer obtained from the Z1-3 position of the section and substituted into the standard formula for calculation. Instead, the area of the compression zone is calculated by changing the formula. Unconventional cross-sections (such as fishbelly cross-sections) can be attempted by checking this option, while general cross-sections do not need to be checked..
Note: This method is not a standardized calculation method, so it is recommended to judge or compare the results on your own..
Screenshot taken from “Design Specification for Highway Reinforced Concrete and Pre stressed Concrete Bridges and Culverts JTG 3362-2018”.
According to Article 5.2.9 (3) of the JTG 3362-2018 specification in the above figure, when calculating the effective height h0, the longitudinal tensile steel bars can be disregarded as bent steel bars..
As shown in the figure below, the pink line represents the prestressed steel tendon. Due to the upward bending at the fulcrum position, h0 will gradually decrease, which may cause the section verification to fail first. According to the article description, we may not consider the bending of steel strands. For example, if this option is entered as 0.2h, the steel strands above the yellow dashed line in the figure will no longer be considered. The causes, detection methods, and reinforcement measures of cracks in concrete structures have been a major challenge for construction technicians for a long time. Cracks in concrete structures, especially in large volume buildings, are a common phenomenon. Therefore, engineering personnel are very concerned about the problem of cracks..
This article classifies cracks in reinforced concrete structures, analyzes the causes of cracks, commonly used detection methods, and various repair and reinforcement measures after cracks appear, for reference by engineering and technical personnel engaged in engineering construction..
The problem of cracks is a common concern for people, and for concrete structures, the existence of cracks is a very common phenomenon. A large amount of scientific research and practice have proven that cracks in concrete structures are inevitable, and the load when cracks appear is often 15% to 25% of the ultimate load..
Under normal usage loads, reinforced concrete structures generally work with cracks, with visible cracks ranging from 0.02 to 0.05mm. Cracks with a width less than 0.05mm are considered harmless cracks, and their impact on waterproofing, corrosion resistance, and load-bearing capacity can be ignored..
The current standard in China for controlling the maximum crack width of concrete structural components under normal operating conditions is 0.3mm. Therefore, from an economic and scientific perspective, a certain degree of cracking is acceptable..
But some cracks can cause a decrease in the load-bearing capacity of the structure and a decrease in its reliability; Although some may not have a significant impact on the bearing capacity, there may be issues such as the detachment of the protective layer on the concrete, accelerated corrosion of steel bars, and carbonation of concrete, which can reduce the durability of the structure or cause leakage, affecting its use..
When the crack width reaches a certain value, it may also endanger the safety of the structure. Therefore, how to evaluate, identify, and repair cracks in concrete structures is of great practical significance for the use and maintenance of the structure..
The causes of crack formation are generally divided into two categories: structural cracks and non structural cracks..
Cracks caused by various static and dynamic loads directly applied. The characteristic of structural failure is that the stress reaches the limit due to insufficient bearing capacity of the structure. This type of crack is quite dangerous, and if not treated properly, it will pose a hidden danger to the safety of the structure..
Cracks caused by indirect effects such as temperature changes, shrinkage, and uneven settlement that constrain the deformation of the structure. This type of crack has little impact on the structural bearing capacity, and repair measures can be taken according to the requirements of structural durability, impermeability, earthquake resistance, and use..
In actual engineering structures, cracks caused by loads only account for about 20% of the total number, while cracks caused by indirect effects account for about 80% of the total number of cracks..
The causes of cracks are complex, and their impact on the structure varies greatly. Only by understanding the structural stress state and the impact of cracks on the structure can corresponding repair measures be determined..
The investigation of crack causes includes investigations into materials and construction quality, design calculation and construction, usage environment and load, etc., which provides a basis for crack analysis..
Determine whether it is a structural crack or a non structural crack through observation of the current situation of cracks and investigation of their causes..
Cracks with a constant width and length belong to stable cracks. As long as their width is not large and meets the requirements of the regulations, their danger is relatively small and they are considered safe components..
The width and length of cracks continue to expand over time, indicating that the stress on the steel bars may approach or reach the flow limit, which has a serious impact on the bearing capacity. Measures should be taken in a timely manner..
Crack detection is the inspection of the current situation of cracks, which provides a basis for crack analysis and hazard assessment by detecting the current situation and drawing a crack distribution map..
The commonly used instruments for crack appearance detection include graduated magnifying glasses, crack comparison cards, etc. The depth of cracks is mainly detected by ultrasonic method or direct core drilling method. The general steps for detection are as follows:.
First, draw the shape of the component that produces the crack, then mark the location and length of the crack on the diagram, and number each crack and indicate the time of crack occurrence. What is the minimum grade requirement for concrete strength in different building structures? The selection of strength grade for structural concrete should meet the bearing capacity, stiffness, and durability requirements of the engineering structure. For concrete structures with a design service life of 50 years, the minimum requirement for the strength grade of structural concrete should also comply with the following regulations:.
The prestressed concrete floor structure should not be lower than C30, and other prestressed concrete structural components should not be lower than C40;.
Structural components that withstand repeated loads should not be lower than C30..
Reinforced concrete structures with seismic resistance levels not lower than Level 2 should not be lower than C30..
Reinforced concrete structures using 500MPa and above grade steel bars should not be lower than C30..
For concrete structures with a design service life greater than 50 years, the minimum strength grade of structural concrete should be increased compared to the above regulations..
The selection of strength grade for concrete structures should consider the characteristics of the engineering structure. Firstly, the bearing capacity, stiffness, and durability requirements of the structure should be met. The design strength should be determined by design calculations, but the minimum strength grade requirements specified in this article should be met to ensure the basic safety and durability of the engineering structure..
The minimum concrete strength grade requirements for concrete structures with a design service life of 50 years are mostly higher than the current relevant standards, in order to appropriately improve the safety and durability of concrete structures:.
1) The minimum strength grade of concrete for plain concrete structures has been increased from C15 to C20, and the minimum strength grade of concrete for reinforced concrete structures has been increased from C20 to C25..
2) For prestressed concrete structural components, the concrete strength grade C30 is the minimum requirement, mainly applicable to floor slabs and other components of building structures (including prefabricated composite floor slabs); For other prestressed concrete structural components (such as bridge structures and beams, columns, etc.), the strength grade of concrete should be increased and should not be lower than C40..
3) For steel-concrete composite structural components, in order to better utilize the efficiency of the two materials, the requirement is proposed that the concrete strength grade should not be lower than C30..
4) For reinforced concrete components with seismic resistance levels not lower than level 2 (including level 2, level 1, and special level 1 in current standards), the requirement that the concrete strength level should not be lower than C30 has been proposed. Compared with the current standards, the requirements for level 2 seismic resistance level components have been appropriately increased..
5) For concrete structures using high-strength steel bars of 500MPa and above, in order to better utilize the performance of high-strength steel bars, the strength grade of concrete should be correspondingly increased. This clause proposes a requirement of no less than C30, which is higher than the current standard C25..
The durability performance of concrete structures during service is related to the design service life of the structure and the environmental conditions exposed to the concrete. Design concrete structures with a working life longer than 50 years, as the durability requirements of the structure are higher, the minimum strength grade of the structural concrete should be further appropriately increased..
The plain concrete structure referred to in this article generally does not include the plain concrete cushion layer of basements or other underground structures; The minimum concrete strength grade of the plain concrete cushion layer should be determined based on the actual engineering situation (including the geotechnical properties of the foundation, etc.). If the depth of the reinforcement is greater than the size of the component and it is not processed, it can cause safety hazards. “Tumumantan” – different perspectives, equally exciting. Click on the blue text “Tumumantan” below the title to follow, and we will provide you with meaningful and valuable knowledge sharing of building structures. How to reinforce concrete structures with insufficient strength? These three reinforcement methods are the most effective! How to reinforce concrete structures with insufficient strength? These three reinforcement methods are the most effective!.
The importance of concrete structure strength in construction engineering is self-evident. It is like the “skeleton” of a building, ensuring the stability and safety of the overall building. Unfortunately, due to design negligence, construction defects, or material quality issues, concrete structures sometimes appear inadequate, resulting in substandard strength..
When the strength of a concrete structure is insufficient, it is like a physically weak person, unable to support excessive loads. This not only weakens the load-bearing capacity of the building, making it unbearable, but may also conceal huge safety hazards, like the sword of Damocles hanging overhead, which can fall at any time..
The seriousness of this problem cannot be ignored, as it can shake the fundamental principles of building structure – bearing capacity and stiffness. Over time, these issues will gradually become apparent, such as structural distortion, deformation, and even the appearance of cracks, which may be signals of insufficient strength. These not only affect the aesthetics and functionality of the building, but may also pose a serious threat to its safety..
In order to safeguard the safety and stability of buildings, we must face this issue and quickly take effective reinforcement measures. In this article, Zhang Bo from the concrete industry will reveal three most effective methods for strengthening concrete structures, helping engineers solve problems and jointly safeguard our building safety..
The problem of insufficient concrete strength can often be traced back to several core reasons..
Firstly, improper operation during the construction process is an important factor leading to damage to the strength of concrete. Any negligence in the mixing, pouring, and curing processes of concrete may affect its final strength performance..
Secondly, the design of concrete mix proportions is also crucial. Inappropriate mix proportions can directly affect the hardness and durability of concrete, just like a recipe in cooking. A slight error in the proportion may affect the taste and quality of the entire dish..
Finally, we cannot ignore the quality issues of raw materials. Using inferior or substandard raw materials is like burying hidden dangers in the foundation of a building, which can potentially cause safety issues at any time..
These potential problems not only reduce the quality of concrete structures, but also lead to a significant decrease in their bearing capacity. Imagine a building whose concrete structure lacks strength, it is like a weak giant that may deform, crack, or even collapse at any time due to its inability to withstand its own weight or external pressure..
Therefore, we must face these issues head-on and ensure the quality of concrete from the source to ensure the safety and stability of the entire construction project..
When the concrete strength is insufficient, its performance will be very obvious. The most direct consequence is a decrease in structural strength, which is like a previously robust person suddenly becoming weak and powerless..
In addition, the crack resistance performance of the structure will also be significantly reduced. The originally sturdy concrete surface may have wide cracks like spider webs, which not only affect the appearance, but may also be a signal of reduced structural safety..
At the same time, components may also undergo significant deformation, such as bending or twisting of critical parts such as beams and columns, which can affect the normal use of buildings and even pose safety hazards..
Therefore, once these signs are detected, immediate measures must be taken for reinforcement and repair to ensure the safety and stability of the building..
The following three reinforcement methods have been proven to be the most effective in addressing the issue of insufficient strength in concrete structures:.
Adhesive steel reinforcement method is a reinforcement technique that uses adhesive steel plates or profiles to enhance the bearing capacity of concrete structures. Its advantages lie in the simplicity and efficiency of the construction process, as well as minimal modifications to the original structure, making it widely favored by engineers..
When the concrete strength of the column cannot meet the design standards, resulting in the bearing capacity and axial compression ratio of the column not meeting the requirements of the building code, we can take an effective reinforcement measure: that is, the steel plate is pasted on the bottom of the beam or plate, and tightly combined with the original column to form a unified whole. This reinforcement method not only significantly improves the bearing capacity of the column to meet the requirements of axial compression ratio, but more importantly, it can effectively enhance the deformation stress of concrete, thereby improving the ductility of the column, making it better able to adapt to deformation and reduce the risk of brittle failure during the stress process. 【 Technical Communication 】 Detailed Explanation of ETABS European Standard Concrete Frame Design Points (II) – Frame Column Design 【 Technical Communication 】 The Influence of Nonlinear Analysis on the Anti floating Calculation of Underground Structures.
[Technical Communication] Questions about Layered Shell Simulated Floor slabs Building Technology | Innovative Construction Technology for Ultra Large Section Steel Concrete Slanted Columns Achieving Maximum Building Area in Limited Field Underground is one of the design concepts pursued by building designers. In the architectural design, the design adopts an upward and downward architectural style, which considers borrowing urban roads to meet the needs of fire protection loops in the first floor design, while maximizing the outward extension of the upper part of the building design, fully utilizing the upper free space to achieve the goal of land conservation and comprehensive utilization of urban facilities. In order to achieve the shape effect of “up, down, and down” in architectural design, a steel reinforced concrete inclined column conversion system with good force transmission is usually used in structural design. By setting diagonal conversion columns connected to the upper and lower frame columns, the force transmission of the structure is relatively clear, reducing the shear force of the beam and significantly reducing the shear compression ratio of the beam; Making diagonal conversion columns withstand both vertical loads and horizontal forces becomes an important lateral force resistant component, which is beneficial for structural seismic resistance. Therefore, researching the pouring technology of steel reinforced concrete inclined columns is particularly important to ensure the achievement of high-quality engineering levels..
The total construction area of four comprehensive buildings and collective dormitories in the southeast region, including the teaching and research building of a certain university, is 1025900 meters ²， The highest point of the building is 81 meters, with 3 underground floors. The individual project of a certain teaching and research building has 18 floors above ground and a total construction area of 66000 meters ²， The above ground building area is 48000 meters ²， Underground area of 18000 meters ²， The overall structure adopts reinforced concrete frame core tube shear wall..
In order to fully utilize the upper building space on one side of Zhongguancun South Street, the first floor urban road was borrowed from the east side of a teaching and research building in a certain university as the fire protection loop of the project, with the upper part extending towards the side of the road. In order to achieve non vertical connection between the upper and lower parts, independent columns with 2 or less floors are used to retreat inwardly on the structure, and a 1:6 diagonal column is made at a height of 3-5 floors to form a vertical structural connection between the 2nd and 6th floors. The total length of the diagonal columns is 17.6 meters..
The seismic resistance level of the inclined columns and their adjacent frame columns and tension beams is a special level, and the structural safety requirements are extremely high. In each row of floors 3-5, there are 6 diagonal columns with large cross-sectional dimensions. The diagonal columns are 1200 mm x 1200 mm and are equipped with cross shaped steel columns of 600 mm x 600 mm x 40 mm x 40 mm, made of Q345GJC material. The diagonal columns are effectively connected to the internal core tube shear wall structure through the diagonal beams, avoiding vertical component discontinuity. Strengthening measures are taken to avoid structural overloading..
The pouring construction process of steel reinforced concrete inclined columns is a key link in the construction process of inclined columns, and it is also the final step to ensure the quality of concrete construction. Taking into account the special shape of inclined columns, such as their large cross-section and ultra long shape, the inclusion of cross shaped steel, stiffeners, shear bolts, and welded steel sleeves, the main technical difficulties in the concrete process are as follows..
The decorative method of the steel reinforced concrete inclined column building is wood hanging board decoration, which belongs to the refined decoration area. The requirements for the flatness and squareness of the external corners of the formed inclined column concrete structure are extremely high. The inclined column is required to be square, with an overall flatness of ± 3 mm, meeting the standards for direct decoration and decoration..
The specification size of steel reinforced concrete diagonal columns is 1200 mm x 1200 mm, which belongs to large section and large volume concrete components. There are strict technical standards for concrete mix proportions, concrete vibration, pouring time, and pouring methods. Due to the cross shaped steel column embedded in the inclined column and the steel column having a certain inclination angle, there are more reinforcement. The conventional bolt type formwork reinforcement system is not suitable, and new formwork reinforcement technical measures must be proposed and reliable to ensure the appearance quality of concrete after pouring..
In the steel reinforced concrete inclined column structure, the steel columns intersect with the steel beams, and the steel bars are densely distributed and the spatial layout of the nodes is complex. The technical difficulty of on-site steel bar cutting and installation is high. The installation quality of steel bars is poor, and the bottom surface of the column is inclined, which can easily cause coarse particles to be blocked by the densely distributed steel reinforcement skeleton during the flow process inside the inclined column, resulting in a serious unreasonable concrete mix ratio at the bottom of the inclined column, causing serious segregation and affecting the construction quality of the inclined column concrete. Taizhou | Notice on the Issuance of Technical Guidelines for Standardized Design of Prefabricated Concrete Members of Residential Buildings in Taizhou (Trial) Part of the content of this official account comes from the network, newspapers and other media. We are neutral about the views in the text, and do not provide any express or implied guarantee for the accuracy, reliability or integrity of the content contained, please only for reference. We respect the author’s work. If there is any suspicion of infringement, please contact us to promptly verify and delete (400-828-9907). This public platform will not assume any responsibility. At the same time, the original articles of this official account can be forwarded, indicating the source. In the appraisal of buildings, how to identify and analyze cracks in concrete components? Cracks are a type of discontinuous phenomenon in solid materials. A large amount of engineering practice has provided experience that cracks in buildings are inevitable, and damage to buildings often begins with cracks. Therefore, in the safety appraisal of buildings, identifying and analyzing cracks is one of the important contents..
A large amount of scientific experimental research and engineering practice have proven that crack problems are common in buildings, and the generation of cracks is determined by the inherent physical properties of materials, which is inevitable and therefore allowed to a certain extent. The dilapidation of a house begins with the formation of cracks. Buildings are easily affected by factors such as design drawings, material characteristics, environmental factors, and foundation settlement, which can lead to the occurrence of cracks. Therefore, in the process of building safety assessment, the reasons for the occurrence of cracks should be considered from multiple aspects to ensure the durability of the house..
01 “Eight” shaped crack.
Mainly appearing at both ends of horizontal and vertical walls. A type of uneven settlement crack in the foundation, when the settlement at both ends of the house is small and the settlement in the middle is large, it forms reverse bending deformation, and diagonal cracks appear on the longitudinal wall. Most of the cracks pass through the two diagonal corners of the window and are distributed in an “eight” shape on the wall..
Another type of crack is temperature shrinkage crack, which is generally located at both ends of the top floor of a house. Sometimes it may develop to one-third of the length of the house, and in severe cases, it may also develop to 1-2 floors below the top floor. The main reason for the formation of this crack is that after the temperature rises, the temperature deformation of the roof panel is greater than that of the masonry, generating a certain amount of temperature stress. The force of the roof panel is transmitted to the wall, causing the top wall to be subjected to tensile and shear forces. The tensile and shear stresses are larger at both ends and smaller in the middle. When the tensile stress exceeds the tensile limit of the masonry, the walls at both ends will crack in an “eight” shape..
02 Inverted “eight” shaped crack.
When the settlement at both ends of the house is large and the settlement in the middle is small, reverse bending deformation occurs, and diagonal cracks appear on the longitudinal wall. Most of the cracks pass through the two diagonal corners of the window and are distributed in an inverted “eight” shape on the wall..
03 Horizontal cracks.
Located at the top longitudinal and transverse walls, parapets, and mountain walls. When the roof insulation is poor, the roof panel expands due to heat, causing horizontal forces on the wall. The wall shrinks more at the end than in the middle and the masonry has lower shear resistance, resulting in horizontal cracks between the wall and the roof panel. In addition, when local uneven settlement occurs in the house, due to the self weight of the wall in the middle and lower cracked area, vertical tensile stress is caused, resulting in horizontal cracks in the wall..
04 Vertical cracks.
It mainly appears at the window sill walls, lintel ends, and floor misalignment. The reason for cracking is that when the temperature difference between the brick masonry and the concrete components is too large, the deformation difference between the brick masonry and the concrete components increases, and they are mutually constrained, resulting in significant tensile stress on the wall and causing it to crack. Vertical cracks generally only occur locally in the wall, with the bottom layer being more severe than the upper layer, and the cracks are wider near the floor slab..
05 X-shaped crack.
Most cracks along the masonry joints are mainly caused by the repeated effects of thermal expansion and contraction of the building, while X-shaped cracks in the bottom wall are caused by uneven foundation or uneven settlement..
The stress cracks of the column vary depending on the stress mode.
01 Axial compression.
When the axial pressure exceeds the bearing capacity of the column, vertical intermittent cracks appear on all four sides of the column..
02 Large eccentric compression.
Horizontal cracks first appear on the side of the column away from the longitudinal force, and then multiple vertical discontinuous cracks appear on the side of the column near the longitudinal force..
03 Small eccentric compression.
Multiple vertical discontinuous cracks appear on one side of the column near the longitudinal force..
The deformation cracks (non stress cracks) of the column are mostly caused by uneven settlement of the foundation or premature demoulding, resulting in horizontal circumferential cracks appearing at the construction joints such as the upper and lower ends of the column. The X-shaped cracks in the column are mostly shear cracks under seismic action..
The stress cracks that appear at the bottom of the mid span of the beam are perpendicular to the beam, wider at the bottom and narrower at the top, gradually tilting from the mid span to both sides, caused by a positive bending moment; The stress cracks that appear at the top of the support edge of the beam, which are wide at the top and narrow at the bottom, are caused by the negative bending moment of the support; The stress cracks that appear outside the edge of the bottom support of the beam are inclined at a 45 ° angle and are caused by bending moment and shear force..
Non stress cracks in beams generally occur on both sides of the beam. The cracks are linear, roughly equidistant, and parallel to the stirrups. The cracks are wide at the top and narrow at the bottom, and are mostly caused by concrete shrinkage and temperature differences. [Paper sharing] The impact of FRP anchor bolt arrangement on the performance of externally bonded FRP slab concrete components. Paper link: http://dx.doi.org/10.1016/j.engstruct.2016.12.005.
Influence of FRP anchor configuration on the behavior of FRP plates externally bonded on concrete members.
The influence of FRP anchor bolt arrangement on the performance of externally bonded FRP slab concrete components.
Source: Engineering Structures.
Author: Togay Ozbakkaloglu, Chengfeng Fang, Aliakbar Gholampour.
This article conducts experimental research on the influence of composite material (FRP) anchoring system on the performance of externally bonded FRP slab concrete components. Single lap shear tests were conducted on 33 specimens with different anchoring systems. The research variables include the anchoring depth, quantity, and construction of FRP anchor bolts. The results indicate that all variables have an impact on the peak bearing capacity of the specimen in the first stage (before the FRP plate peeling), and the impact on the peak bearing capacity of the specimen in the second stage is more significant. The number and arrangement of anchor bolts have a significant impact on the load slip performance of FRP panels. The shape of the strain curve of FRP panels is influenced by the arrangement of anchor bolts. FRP plates with longitudinal anchoring structures have a larger maximum strain value than FRP plates with transverse anchoring structures..
Fiber reinforced composite materials (FRP) are renowned for their lightweight, high strength, corrosion resistance, and ease of installation. In recent years, a large number of researchers have conducted experimental studies on FRP and found that sticking it to the outer surface of concrete components can significantly improve the mechanical properties of the components. However, the failure of FRP concrete composite components often occurs at the interface, leading to the failure of the components before the performance of both concrete and FRP materials is fully utilized, greatly reducing the efficiency of material utilization. In order to prevent or delay the delamination of FRP panels, relevant scholars use anchor bolts, U-shaped FRP anchors, etc. to reinforce FRP concrete components. Among them, FRP anchor rods are a popular reinforcement technology. Therefore, researchers conducted a large number of experiments with the diameter, quantity, and type of FRP anchor rods as variables to investigate the effect of FRP anchor rods on the interface performance of FRP concrete. Based on this, the author hopes to further improve the relevant experimental research on the basis of previous studies..
This study designed a total of 33 single lap shear specimens, with experimental variables including the number of anchor bolts, anchor position, anchor depth, and anchor bolt arrangement. When installing anchor bolts, the “flexible” installation method is adopted, and the fibers scattered at one end of the FRP anchor rod are laid flat on the FRP plate. Use strain gauges and displacement gauges to measure the strain value of FRP panels and the relative slip value between FRP panels and concrete. The failure modes of each group of specimens and the ultimate bearing capacity of specimens at each stage were recorded, and the reasons for the differences in failure modes were preliminarily analyzed. Subsequently, the author organized the experimental data and summarized the influence of anchor depth, arrangement method, and number of anchor bolts on the ultimate bearing capacity of the first and second stages of the specimen. The experimental data was used to verify the predictive model of bearing capacity proposed by previous scholars. Finally, the relative slip data between FRP plates and concrete obtained from the experiment, as well as the strain gauge data of FRP plates, were organized to obtain the load slip curve of the specimens and the strain distribution curve of FRP plates at different positions..
(1) As the number and depth of anchor bolts increase, the ultimate bearing capacity load (i.e. Pmax1 and Pmax2), interface ductility, and maximum strain values of the specimen in the first and second stages increase;.
