Design Support Research Articles

Automated force-flow-oriented reinforcement integration for Shotcrete 3D Printing

The construction industry faces various challenges, e.g. reducing its carbon footprint and the extensive use of materials. Therefore, Computational Design and Additive Manufacturing gain more importance throughout the industry. In combination, they offer the possibility of manufacturing individually designed building components, which can be less material-consuming and structurally improved. The presented research displays and discusses the effect of force-flow-oriented reinforcement design in concrete beams concerning the flexural strength and the required amount of steel. For this purpose, different reinforcement layouts were designed and integrated into conventionally cast and additively manufactured beam components. For the design of the force-flow-oriented reinforcement layouts, a digital workflow is established, and FEM simulations are utilised. The load-bearing capacity of the beams is compared based on four-point bending tests. Due to the optimised reinforcement layout, an increase of flexural strength of more than 60% was achieved while keeping the reinforcement amount constant. It is also shown that using force-flow-oriented reinforcement layouts can save nearly 60% of the reinforcement needed to achieve the same flexural strength as a beam with a conventional reinforcement cage. Finally, the potential for automated force-flow-oriented reinforcement integration within additively manufactured components is discussed.

Investigation on bonding behavior of basalt fiber reinforced polymer (BFRP) sheet reinforced concrete beam

Although basalt fiber reinforced polymer (BFRP) sheet offers promising benefits including environmental friendliness and excellent mechanical performance in concrete reinforcement, its full potential is still hindered by the lack of understanding about their bonding mechanism. Therefore, the comprehensive investigation of the bonding behavior of BFRP sheet reinforced concrete is necessary. This work aims to address the research gap between the analytical design and industrial application of BFRP sheet reinforced concrete due to the complicated bonding behavior. Analytical method, experimental measurement, and numerical simulation are employed to comprehensively investigate the bonding behavior of BFRP sheet reinforced concrete. According to the mechanical model and assumptions of the reinforcement, analytical solutions for interfacial stress and strain are derived. In addition, four-point bending test are conducted on specimens, and multi-view digital image correlation (DIC) technique is used to analyze the deformation on concrete part and BFRP sheet simultaneously. Based on analytical and experimental results, finite element model (FEM) is applied to simulate mechanical behavior of BFRP sheet reinforced concrete beam, and parametric analysis is further conducted. Results reveals that the maximum interfacial stress appears at the end of bonding region so that BFRP debonding at the end is the main failure mode. The strain distribution of BFRP sheet obtained by multi-view DIC indicates that there is an effective bonding region. Besides, strain can be used as a variable to validate numerical model by analytical and experimental results. The validated numerical simulation could be conducted for the internal response study and application design of BFRP sheet reinforcement.

Characterizing transition zone between steel‐concrete composite and reinforced concrete members

AbstractSteel profiles are often embedded in reinforced concrete (RC) members (specially columns) to achieve higher performance in a localised manner. Although the RC and steel‐concrete composite zones of such members can be respectively designed according to the Eurocodes 2 and 4, the transition zone between the steel profile and its surrounding concrete needs to be adequately designed to ensure an effective transmission of the axial force, shear and bending moments carried by the interrupted steel component. This is currently not covered by the design standards and is only partially covered by the current literature. This article proposes a design procedure for such transition zones relying on a 2‐steps approach: (1) Definition of the transverse load to be transferred from the steel part of the composite zone to the RC part, based on a reasonable distribution of the contact pressure between the profile and the surrounding concrete; and (2) Evaluation of a suitable “strut & tie” mechanism to ensure the appropriate transfer of this load and consecutive design of the transverse reinforcement. In order to evaluate the efficiency of the design approach, the transition zone between a composite and a pure RC part of a locally composite column was investigated experimentally. Four test specimens were designed and tested in order to study the influence of certain parameters, e.g. length of the assumed transfer zone, presence of one or two lateral beams at the level of the transfer zone, compression level in the column, etc.

FINDING THE OPTIMAL REINFORCEMENT FOR VERY DEEP BORED PILE FOUNDATION

The foundation is the most important part of any structure in the construction process. A failure in the foundation can cause the entire structure to fail if cannot withstand the forces or weight of the structure above. The foundation is required to bear the external loads or weight of the structure, even though the upper structure may be strong and sturdy. Bored pile foundation is the most commonly used foundation type for building projects or multi-story structures. The distribution of forces on pile foundations is inversely proportional to its depth, and the part of the pile close to the forces will bear a greater load than the deeper part of the pile. This consideration makes the design of reinforcement for pile foundations variable according to the distribution of forces acting on the pile according to its depth. This study analyzes the reinforcement requirements for a pile foundation using laboratory-calculated soil parameters and data specific to the Jakarta area. The first step is to determine the soil parameters, then calculate the force diagram using the Matlock and Reese method, and finally, determine the reinforcement requirements based on the force diagram obtained. After that, the calculated reinforcement needs to be adjusted according to the applicable requirements for a pile with a length of 65 meters and a diameter of 1800 mm. The required reinforcement is D13-75 for transverse reinforcement, 20D32, 16D29, and 8D32 for longitudinal reinforcement according to their depth.

Surface crack growth in metallic pipes reinforced with Fibre-Reinforced Polymers subjected to cyclic loads: An analytical approach

This paper introduces a novel analytical approach aimed at predicting the growth of surface cracks in metallic pipes reinforced with Fibre-Reinforced Polymers (FRPs) subjected to cyclic bending and/or tension loads. The primary objective of this study is to develop a comprehensive analytical model that accounts for multiple factors influencing crack growth, namely stress reduction, crack-bridging effect, stiffness degradation, and fatigue damage of the FRP-to-metal interface simultaneously. By considering these simultaneous effects, our proposed approach enables accurate evaluations of the stress intensity factors (SIFs) at both the surface point and the deepest point of a surface crack. To facilitate practical implementation, we have developed an in-house program that automates crack growth rate and residual fatigue life predictions. The proposed analytical method has been validated through a series of comparisons with experimental data and finite element results, demonstrating its accuracy in estimating fatigue lives. The key novelties of this research lie in the holistic consideration of multiple dominating and influencing factors, the achievement of precise SIF evaluations, and the development of an automated prediction tool for practical applications. Overall, our findings confirm the suitability of the proposed analytical approach for predicting crack growth and provide valuable insights for guiding the design of FRP reinforcement in surface-cracked metallic pipes. This work contributes to advancing the understanding of crack growth behaviour in FRP-reinforced metallic pipes and opens new possibilities for the safe and efficient design of such structures.

Experimental Study and Bearing Capacity Analysis of Retrofitted Built-Up Steel Angle Members under Axial Compression

Against the update of load design standards and requirement of long-term service, many latticed towers using steel angles subjected to gradual performance degradation must be retrofitted for bearing further social functions, e.g., electric power transmission and fifth-generation mobile communication. Therefore, this paper proposed a non-destructive reinforcement method for steel angles by avoiding unnecessary new construction or complex reinforcement procedure. The non-destructive reinforcement of a steel angle is composed of a steel angle, reinforcement plate, and fixture. Standardized fixtures are used to connect the reinforcement plate and steel angle to achieve steel angle reinforcement. In retrofitting tests, built-up steel angle members were loaded under axial compression, in which the failure mode and reinforcement effect of key parameters (e.g., clamp type, slenderness ratio, and clamp distance) were analyzed and compared, where a significant reinforcement effect was obtained with the capacity increment within 39~174%; the clamp types and clamp distance had a slight effect on bearing capacity; and the proposed reinforcement method was more effective for slender members. Based on the mechanical mechanism analysis and failure mode, the accuracy of the design method for calculating the bearing capacity of those built-up steel angle members was suggested and verified, in which a simplified mechanical model for the flexural-buckling mode was developed. The design method based on AISC360-16 agreed well with the test result and could be effectively used for calculating the flexural–torsional bearing capacity of those built-up steel angles. This study can provide a valuable reference for the design and application of non-destructive reinforcement of angle steel towers.

Changes in SNI-1726 and SNI-2847’S Effects on Low-Rise Reinforced Concrete Buildings’s Reinforcing Steel Weight

The updates of the Indonesian seismic design code (SNI 1726) and the reinforced concrete design code (SNI 2847) have been applied in practice simultaneously. Based on these new codes, seismic loads generally increase, especially for low-rise buildings, and the reinforcement design requirements become much more stringent. Therefore, the construction industry predicts that there will be a significant increase in the need for reinforcing steel. This paper would like to describe the comparison of the design reinforcing steel weight in a 4-story reinforced concrete case study building with a special moment resisting frame system, which is designed using a combination of SNI 1726:2012 and SNI 2847:2013, and which is designed using a combination of SNI 1726:2019 and SNI 2847:2019. This study was found that the increase in reinforcing steel is not proportional to the increase in seismic load and much smaller. This result can then be an illustration of how much increase in design reinforcing steel when using the new codes.

Deformation Behavior of Carbon Fiber/Al Composites with Corrugated Structure for Developing the Rolling Plate

Herein, a rolling strategy for carbon fiber (CF)/Al composites is proposed, that is, by constructing a corrugated structure of Sn‐protected CFs ([CF@Sn]≈Al composites), to realize the cooperative extension of woven CFs with Al matrix deformation in the rolling process. The matching extension feasibility and structural optimization of (CF@Sn]≈Al composites are calculated based on the designed 3D numerical model of rolling system. The [CF@Sn]≈Al composites have successfully combined excellent mechanical properties while meeting the extension design of the CF reinforcement. Mechanical testing of the samples indicates that the tensile strength of the [CF@Sn]≈Al composites increases by 18.6% while the bending strength is more than 23.2% higher than that of the rolled Al matrix. The present work provides an effective method for developing the deformed CF/Al composites as rolling plate in lightweight applications.

Research on Dynamic Deformation Laws of Super High-Rise Buildings and Visualization Based on GB-RAR and LiDAR Technology

It is well-known that structures composed of super high-rise buildings accumulate damages gradually due to ultra-long loads, material aging, and component defects. Thus, the bearing capacity of the structures can be significantly decreased. In addition, these effects may cause inestimable life and property losses upon strong winds, earthquakes, and other heavy loads. Hence, it is necessary to develop real-time health monitoring methods for super high-rise buildings to deeply understand the running state during operation, timely discover potential safety potentials, and to provide reference data for reinforcement design. Along these lines, in this work, the built super high-rise buildings (Yunding Building) and super high-rise buildings (the Main Tower of the Shandong International Financial Center), under construction, were selected as the research objects. The overall dynamic deformation laws of super high-rise buildings were monitored by using ground-based real aperture radar (GB-RAR) technology for its advantages in non-contact measurement, remote monitoring, and real-time display of observation results. Denoising of the observation data was also carried out based on wavelet analysis. The visualization of the space state of the Yunding Building was realized based on handheld LiDAR technology. From the acquired results, it was demonstrated that the measuring accuracy of GB-RAR could reach the submillimeter level, while the noises under a natural state of wavelet analysis were eliminated well. The maximum deformation values of the Yunding Building and the Main Tower of Shandong International Financial Center under their natural state were 9.63 mm and 16.46 mm, respectively. Under sudden wind loads, the maximum deformation of the Yunding Building could be as high as 895.79 mm. The overall motion state switched between an S-shaped pattern, hyperbolic-type, and oblique line, presented the characteristics of nonlinear elastic deformation.

Reinforcement detail: Stress trajectory‐oriented corbel reinforcement

AbstractThe article presents a novel design of concrete corbels, where horizontal and vertical stirrups are replaced by main reinforcement bars that are bent down into the corbel web, following the principal stress lines. A test series of three specimen pairs of fanned‐out and conventional reinforcement design, supported by finite element analysis, shows that the same capacity can be achieved with a significantly lower amount of reinforcement steel and a higher ductility.

Study on hysteresis constitutive and fracture behaviors of corroded constructional steel under artificial atmospheric environment

In order to evaluate the seismic capacity of corroded steel structures in natural atmospheric environment, 18 steel plates with 6 corrosion ages obtained by artificial accelerated test were employed to the cyclic loading tests. A comprehensive corrosion parameter (D) considering the uniform and pitting corrosion was proposed, and used to study the effect of corrosion on the resistance and hysteretic behavior of corroded steel. The results showed that, with increase of D, both of the position of skeleton curves and the peak values of stress cycles were decreased significantly, the yield platform disappeared, and the elastic modulus and ultimate strength decreased sharply; D was also closely related to its energy-dissipating capacity. Then, D was applied to optimize the constitutive parameters and fracture parameters, and a Chaboche plastic constitutive (CPC) model was established to simulate the hysteretic behavior of corroded steel with very high accuracy. Besides, the relationships of fracture parameters (εpl and G) and D were also given. Finally, combined with fracture morphology, the fracture analysis of corroded steel under cycle load was performed. The dimples size on fracture was reduced with increase of D, the ductility would be degraded. While D greater than 4.8, the change rate of εpl and G showed a sudden change, that meant the fracture behavior tends to brittleness, and should be paid more attention to in the seismic reinforcement design of existing steel structure.

The shear resistance mechanism of prestressed anchor cables in slope reinforcement

At present, for the reinforcement effect of prestressed anchor cables, only the shear resistance produced by prestress is considered in slope reinforcement design, which greatly underestimates the shear resistance of anchor cables. To investigate the shear resistance effect of prestressed anchor cables, a large-scale shear test system of anchored joint with sample dimensions of 70 × 70 × 140 cm was developed in this study. The test results revealed the interaction mechanism of extrusion and disengaging between the anchor cable and local surrounding rock in the process of shear deformation, the reversed ‘S’-shaped deformation characteristics of the anchor cable, and the combined tensile-shear failure mechanism. Based on the test results, the shear deformation and shear resistance characteristics of the anchored joint in different phases were thoroughly analysed, and a three-stage shear deformation model for anchor cables was proposed. In addition, the corresponding mechanical analysis model for shear resistance of anchor cables was developed. The comparative verification revealed that the error between the model calculated results and the test results was within 6%.

Experimental investigations on early crack development in fully restrained reinforced concrete members with active zero-displacement control

The development of restraint-induced stress in reinforced concrete members at an early age can be tested using setups applying either passive or active displacement control. To provide results relevant for the practical design of minimum reinforcement to limit the crack width, an actively controlled test setup for large specimens was developed to perform a systematic experimental campaign focusing on the early crack development under well-defined mechanical and thermal boundary conditions. The full degree of restraint achieved by actively preventing any displacement of the member allowed for the theoretical interpretation of early restraint-induced stress evolution, deformation behaviour in the cracked and uncracked regions, and reinforcement stress for a variety of parameters, including hydration rates, member height, bar diameters and subsequently reinforcement ratio. The cracking process, starting with primary cracks accompanied by secondary cracks within the effective reinforcement area, is monitored in combination with the development of the tensile strength and Young’s modulus of the concrete. Furthermore, the time of cracking and the forces released upon crack occurrence, considering the effect of self-equilibrating stresses, are determined, analysed, and compared with the results of crack-force based design rules to determine the minimum amount of reinforcement that ensures the crack width limitation.

Heavy Ion Single Event Effects in CMOS Image Sensors: SET and SEU

High-energy particles in space often induce single event effects in CMOS image sensors, resulting in performance degradation and functional failure. This paper focuses on the formation and morphology of transient bright spots in CMOS image sensors and analyzes the formation process of transient bright spots by conducting heavy ion irradiation experiments to obtain the variation law of transient bright spots with heavy ion linear energy transfer values and background gray values; in addition, we classify the single event upset that occurred in the experiments according to the state of transient bright spots and extract the characteristics of different single event upsets. The failure mechanisms of different single event upsets are analyzed according to their characteristics and are combined with the information given by transient bright spots. This provides an essential reference for rapidly evaluating single event effects and the reinforcement design of CMOS image sensors.

Enhancing the mechanical and electrical conductivity of copper matrix composites through grafting carbonized polymer dots (CPD) onto carbon nanotube surfaces

Tailoring the structural design of reinforcement is an effective strategy to attain the homogeneous dispersion and robust interface bonding in carbon nanotubes reinforced copper (CNTs/Cu) composites. Herein, a novel zero-dimensional carbonized polymer dots (CPD) was synthesized and grafted onto the CNTs surfaces via a typical one-step hydrothermal method. The resultant reinforcement, CPD@CNTs, exhibited good dispersibility due to the abundant polar functional groups on CPD. Furthermore, the interface adhesion was also ameliorated by means of the in-situ formed Cu2O transient phase. The CPD@CNTs/Cu composite shows outstanding mechanical performances, the yield strength and tensile strength had increased to 269 MPa and 308 MPa, while maintained excellent ductility (43 %). Moreover, the electrical conductivity of the composite remains at a high level of 95.3 %IACS. Our findings suggest that adjusting the structural configuration of reinforcement is a feasible approach to optimize dispersion and interfacial structure.

Design and seismic performance of precast segmental bridge columns repaired with UHPC jacket after earthquake-induced damage

Precast Segment Bridge Columns (PSBCs), which attract more attention owing to the merits of faster construction rate and higher construction quality compared with monolithic columns, are prone to serious damage under a severe earthquake. Seismic performance improvement and rehabilitation of earthquake-damaged PSBCs are significant to promote applications in seismic-prone areas. Ultra-high performance concrete (UHPC) jackets, which are promising in the field of rapid retrofit of civil structures, were used to retrofit damaged PSBCs in this study. To investigate the seismic design method and performance of repaired PSBCs using UHPC jackets, a 1/10-scale earthquake-induced damaged PSBC was retrofitted based on a proposed reinforcement design method, and tested under vertical loading and incremental lateral cyclic loading. The failure mode, hysteresis curve, residual displacement, and energy dissipation capacity of the repaired column were compared with those of the original column. In addition, based on a verified 3D finite element model by the test, a parameter analysis was conducted to explore the effect of the height and wall thickness of the UHPC jacket on the seismic behavior of the repaired PSBCs. The results indicated that the earthquake-damaged PSBC repaired with the UHPC jacket had an equivalent initial stiffness, 18.9% higher energy dissipating ability at 4.0% drift ratio and 16.2% larger strength compared with the undamaged column. The numerical simulation showed that the height and thickness of the UHPC jacket had an influence on the failure location and strength of the repaired PSBCs. Besides, the design method for the damaged precast column reinforced with the UHPC was confirmed by the test and finite element model, and it could be applied to the retrofit design of the damaged precast segment column.

A quantitative analysis of optimum design for rigid ankle foot orthoses: The effect of thickness and reinforcement design on stiffness.

An ankle foot orthosis (AFO) which is prescribed to be rigid should only deform a small amount to achieve its clinical goals. Material thickness and the design of reinforcing features can significantly affect AFO rigidity, but their selection remains based on anecdotal evidence. To quantify the effect of these parameters on AFO stiffness and to set the basis for quantitative guidelines for the design optimisation of rigid AFOs. Experimental and computational study. A polypropylene AFO was produced according to UK standard practice and its stiffness was experimentally measured for 30Nm of dorsiflexion. Its geometry and mechanical characteristics were utilised to create a finite element (FE) model of a typical AFO prescribed to be rigid. Following validation, the model was used to quantify the effect of material thickness and reinforcement design (i.e., reinforcement placement, length) on stiffness. A final set of AFO samples was produced to experimentally confirm key findings. For a specific AFO geometry and loading magnitude, there is a thickness threshold below which the AFO cannot effectively resist flexion and buckles. FE modelling showed that stiffness is maximised when reinforcements are placed at the anterior-most position possible. This key finding was also experimentally confirmed. The stiffness of an AFO reinforced according to standard practice with lateral and medial ribbing was 4.4 ± 0.1 Nm/degree. Instructing the orthotic technician to move the ribbings anteriorly increased stiffness by 22%. Further stiffening is achieved by ensuring the reinforcements extend from the footplate to at least two-thirds of the AFO's total height.

Disain Kebutuhan Tulangan Glass Fiber Reinforced Polymer (GFRP) Untuk Elemen Struktur Pada Bangunan Beton Bertulang

Fiber Reinforced Polymer is a combination of two main materials Resin Polymer (plastic) as a binder matrix and Fiber (fiber) as reinforcement. This material has three fibers, namely Carbon, Glass, and Aramid. Glass fiber was used in this study, because it has a greater strain compared to other fibers. This study aims to design reinforced concrete structures using steel reinforcement and GFRP as well as to compare the reinforcement requirements of each reinforced concrete. Calculation of reinforcement for steel reinforced concrete refers to SNI 1726-2019, while for GFRP reinforced concrete it is based on ACI 440 1R-2015. This research begins by collecting data in the form of a design structure drawing of a 6-storey hypothetical building, with a total building height of 23 m. The hypothesis building has the number of spans in the X-axis direction is 5 with a distance between columns of 6 m, while the number of spans in the Y direction is 3 with a distance between columns of 5 m. The column dimensions for all floors are 60 cm x 60 cm, while the beam dimensions are 40 cm x 40 cm. The thickness of the floor and roof slabs is 12 cm and the concrete quality is 30 MPa. For the calculation of structural loading, dead load, live load and earthquake load are used and the design of reinforcement for conventional steel reinforced concrete structures and GFRP is carried out. Steel reinforced concrete structures with GFRP reinforced concrete have differences in the amount and diameter of reinforcement required. For beam elements bearing steel reinforcement, 24 pieces of flexural reinforcement are needed with a diameter of 19 mm, while for beam elements, GFRP reinforcement requires 12 pieces of flexural reinforcement with a diameter of 1 inch to 1,128 inches. For the field area, steel reinforcement beam elements need 12 pieces with a diameter of 19 mm, while for GFRP reinforcing beam elements require 8 pieces of flexural reinforcement with a diameter of 0.875 inch to 1.128 inch. In column elements, steel reinforcement and GFRP reinforcement require the same amount of main reinforcement, which is 32 pieces. However, in terms of diameter, steel reinforcement requires 25 mm diameter reinforcement, while GFRP is 1 inch in diameter.

Research on the road performance of self-adhesive basalt fiber geotextiles based on the background of long-life pavements

Achieving sustained asphalt pavements can minimize the structural damage brought on by minor pavement cracks, which will reduce the high repair and maintenance costs resulting from pavement distress. This study introduces a new composite geomaterial, self-adhesive basalt fiber geotextiles (SBFG) prepared by hot-melt lamination of basalt fiber cloth and modified asphalt, intended for the deterrence and control of reflection cracks in asphalt pavements. In this study, the self-adhesive geotextile was placed between the cement-stabilized macadam base and AC-20 surface layer to prepare composite samples, and the road performance was evaluated by a three-point bending test, Overlay Tester, dynamic shear rheology test, and the crack expansion time under different parameters of SBFG was simulated by ABAQUS finite element to predict the whole life cycle of the pavement structure. The results indicate that the fracture energy of the SBFG sample is the largest among all samples, and the structural design of fiber reinforcement disperses the concentrated stress at the crack tip, increases the stress area, and prolongs the time of crack expansion from the subgrade to the surface layer; Smooth and stable load loss curve of the sample in the reflection crack test, with slow crack expansion. This new geomaterial has an excellent rutting factor and maintains good resistance to permanent deformation at high temperatures; In the finite element prediction of fatigue cracking life of asphalt pavement, the structural life of the pavement with the addition of SBFG was improved by 78.3% compared to the control group. The application of basalt fibers in geosynthetics provides a new idea for achieving prolonged asphalt pavements.

Node-reinforced hollow-strut metal lattice materials for higher strength

Intricate hollow-strut metal lattices are novel cellular materials or metamaterials. However, their hollow nodal regions often lead to premature failure under stress. This study reports a design strategy to substantially improve the strength of hollow-strut metal lattices by applying nodal reinforcement. The proposed nodal reinforcement designs increased the yield strength of hollow-strut Ti-6Al-4V cubic lattices by up to 144% and elastic modulus by up to 113% with a modest 21% increase in density compared to the unreinforced lattices. In addition, a 42% increase in peak stress was observed when compared to solid-strut Ti-6Al-4V cubic lattices of similar densities. These properties exceeded the empirical upper limits of the Gibson-Ashby model for cellular metallic materials, thus extending the property envelope. Distinct failure modes were observed for the proposed nodal reinforcement designs. Numerical analysis clarified their role in determining the deformation response.