Construction Joints Research Articles

Experimental Studies of Low-Reinforced Concrete Structures Containing Inter-Bay Construction Joints Strengthened with Prestressed Basalt Composite Reinforcements and External Transverse Reinforcements

During the long-term operation of main run-of-river head powerhouses for hydroelectric power plants, technical changes that deteriorate the operational properties of their reinforced concrete structures can occur. Therefore, in order to substantiate the application of prestressed basalt composite reinforcements to strengthen reinforced concrete hydraulic structures in operation, a set of computational and experimental studies was carried out, taking into account their characteristic features. After 4 years of ageing, the serviceability and reliability of the beams with prestressed basalt composite reinforcements were demonstrated through stabilisation of the prestress losses and the values obtained for bearing capacity, deflection, and the width of the opening of the inter-bay construction joints and the deformations of the metal reinforcements and the basalt composite reinforcements. The bearing capacity of the investigated reinforced concrete beams reinforced with external transverse reinforcements was increased 1.4–2.5 times over that of the variants reinforced with longitudinal prestressed basal composite reinforcements. Furthermore, in this study, the impacts of static loads and seismic effects with a magnitude greater than 8 on the run-of-river hydroelectric power plant powerhouse were calculated based on dynamic design theory. Regarding applications to hydroelectric power plant structures and constructions, for which it is not always possible to determine the location of compressed or tensile zones during their operation nor under seismic action, our research results are suggestive of a reasonably positive effect.

Laparoscopy-assisted versus open surgery for low rectal cancer (LASRE): 3-year survival outcomes of a multicentre, randomised, controlled, non-inferiority trial

Laparoscopic surgery is increasingly used for rectal cancer, but the long-term oncological outcomes for low rectal cancer have not been fully established. We aimed to evaluate the 3-year survival outcomes of laparoscopic surgery versus open surgery in the treatment of low rectal cancer. This multicentre, randomised, controlled, non-inferiority trial was conducted at 22 tertiary hospitals in China. Individuals aged 18-75 years with histologically confirmed cT1-2N0, cT3-4aN0, or cT1-4aN1-2 rectal adenocarcinoma within 5 cm from the dentate line were eligible for inclusion. Participants were randomly assigned (2:1) to undergo laparoscopic surgery or open surgery. Central randomisation was conducted using a web response system, and was stratified by clinical stage, age, sex, BMI, and American Society of Anesthesiologists classification. Investigators, patients and statisticians were not masked to group allocation. The primary outcome was 3-year disease-free survival, defined as the time from the date of surgery to the date of locoregional recurrence, distant metastasis, or death from any cause, whichever occurred first. Non-inferiority was defined as a lower limit of one-sided 97·5% CI for group difference (laparoscopic surgery group minus open surgery group) of greater than -10%. The primary analyses were performed in the modified intention-to-treat population, which excluded patients with distant metastasis discovered during surgery and those who did not undergo surgery or underwent local resection only. The trial is registered with ClinicalTrials.gov, NCT01899547, and has been completed. Between Nov 12, 2013, and June 6, 2018, 1070 patients were enrolled and randomly assigned to treatment. 1039 patients (685 in the laparoscopic surgery group and 354 in the open surgery group; median age 57 years, IQR 50 to 64; 620 [60%] male and 419 [40%] women) were included in the modified intention-to-treat analysis. 3-year disease-free survival was 81·4% (95% CI 78·2 to 84·1) in the laparoscopic surgery group and 79·8% (75·2 to 83·6) in the open surgery group (hazard ratio [HR] 0·92, 95% CI 0·69 to 1·23; p=0·56). The difference between groups was 1·60% (one-sided 97·5% CI -3·34 to ∞, p<0·0001 for non-inferiority). 3-year overall survival was 91·7% (95% CI 89·3 to 93·5) in the laparoscopic surgery group and 93·7% (90·6 to 95·8) in the open surgery group (HR 1·34, 95% CI 0·82 to 2·19; p=0·24). 3-year locoregional recurrence was 3·7% (95% CI 2·5 to 5·3) and 2·3% (1·1 to 4·3), respectively (HR 1·64, 95% CI 0·74 to 3·63; p=0·22). 5-year overall survival was 84·6% (95% CI 81·5 to 87·1) and 86·6% (82·5 to 89·8) in the open group (HR 1·16, 95% CI 0·82 to 1·64; p=0·41). Laparoscopic surgery performed by experienced surgeons is non-inferior to open surgery for 3-year disease-free survival among patients with low rectal cancer. These results support the use of laparoscopic surgery for low rectal cancer. The Key Clinical Specialty Discipline Construction Program of the National Health and Family Planning Commission of China; Minimally Invasive Medical Center Construction Program, Fujian Province, China; and Joint Funds for the Innovation of Science and Technology, Fujian Province, China.

Implementation of Knowledge Sharing in Learning to Write Essay Through Genre Based Approach

The aim of this research is to obtain an overview of improving essay-writing skills through implementing knowledge sharing in the genre pedagogy approach (Genre Based Approach) in The Indonesian Language and Literature Education Study Program at higher education. The research design uses quantitative methods (pretest posttest design) and qualitative data in the form of student responses to applied knowledge sharing. The research sample consisted of 20 students who took part in writing lessons. The data obtained is in the form of essay texts based on the stages of guided construction, independent construction in the form of average scores on the pretest and posttest. The results of the research are test scores with an average of 75.1 and at posttest 85.3. The results of the second research are the percentage of responses via Google Form (as a form of implementation of the socialization of 'tacit knowledge' to externalization' resulting in construction products, both joint and independent construction. Through the application of knowledge sharing and genre pedagogy, it appears that the student response is that knowledge sharing can stimulate critical thinking, sharing knowledge creates learning outcomes products, accommodating the implementation of joint construction as part of the genre-based approach stage, with a high response.

Impact of coopetition on the performance outcomes of international construction joint ventures: a contingency and configuration approach

Impact of coopetition on the performance outcomes of international construction joint ventures: a contingency and configuration approach

Assessing risk allocation preferences of partners in international construction joint venture projects in Ghana

Assessing risk allocation preferences of partners in international construction joint venture projects in Ghana

Performance of Steel Spliced Reinforced Concrete Beams Having Construction Joints

Performance of Steel Spliced Reinforced Concrete Beams Having Construction Joints

Finite Element Analysis of Reinforced Self Consolidation Concrete Beams Having a Horizontal Construction Joint

Finite Element Analysis of Reinforced Self Consolidation Concrete Beams Having a Horizontal Construction Joint

Analysis of water inrush of a deep excavation triggered by river bank failure and its reconstruction

Many deep excavation projects are adjacent to river, and hence face the seepage risk. In this study, a through-wall seepage failure of a foundation pit adjacent to river is investigated. It is found that, the accident was initiated by the breakage of revetment along the construction joint and cracks of rubble stone masonry, which further caused the slope failure of river bank and the subsequent seepage of river water through the cold joint of waterproof curtain. The remedial works including construction of cofferdam in the river, backfill outside the foundation pit, reinforcement of cold joint, backfill inside the foundation pit, controllable dewatering outside the foundation pit and axial force adjustment of struts are designed. The monitoring results indicate effective implementation of the remedial works and the following successful reconstruction of the project. A summary of reported seepage failure cases adjacent to river is finally made to provide suggestions for the design and construction of future similar deep excavation projects.

The Effect of Construction Joints on the Behavior of Reinforced Concrete Deep Beams

The Effect of Construction Joints on the Behavior of Reinforced Concrete Deep Beams

Experimental study on the behavior of small-scaled circular and square RC columns under various loading conditions and corrosion effect

Reinforced concrete columns are vital load-bearing elements, responsible for transferring vertical loads and resisting lateral forces. While numerous factors govern column performance, this study pinpoints cross-sectional shape, transverse reinforcement configuration, and the corrosive threat as its primary areas of investigation. Thus, 20 small-scaled (1/8th scale) RC columns (square and circular, with ties or spirals) were tested under various loading conditions. Columns were divided into five groups. A preliminary test was conducted to determine individual axial load capacity through failure under axial compressive loading. The main test then explored their behavior under combined axial load and variable lateral drift compared to their behavior at two corrosion levels 15% and 25%. While corrosion levels were roughly achieved, uneven distribution due to the accelerated process concentrated pitting near construction joints, impacting reinforcement more than rebar. Results confirmed the efficacy of spirals in enhancing capacity, particularly for circular columns where they also increased lateral load capacity. However, spirals also amplified corrosion vulnerability in circular columns, suggesting a steeper decline in performance at higher corrosion levels. Two key models were derived from analyzing the recorded data: normalized total dissipated energy and normalized absolute peak load. Future research should prioritize exploring column behavior under a wider range of combined loads and corrosion levels to refine and validate these models.

Thermal Stability and Heat Transfer of Polyurethanes for Joints Applications of Wooden Structures.

Wood characterized by desired mechanical properties and wood joining material is essential for creating wooden structures. The polymer adhesives are suitable for such applications due to the possibility of energy dissipation from stresses generated by wooden structures and the elimination of thermal bridging, which are common problems in metal joining materials. This research focuses on the thermophysical properties of the laboratory-prepared flexible and rigid polyurethanes to select an appropriate polymer adhesive. Our results showed that the highest thermal stability was in the case of the new PSTF-S adhesive, which reached 230 °C, but the lowest mass loss in the air environment was around 54% for the PS material. The mean thermal expansion coefficient for F&R PU adhesives was 124-164∙10-6 K-1. The thermal diffusivity of examined adhesives varied between 0.100 and 0.180 mm2s-1. The thermal conductivity, depending on the type of polyurethane, was in the 0.13-0.29 W∙m-1∙K-1 range. The relative decrease in thermal diffusivity after heating the adhesives to 150 °C was from 2% for materials with the lowest diffusivity to 23% for the PU with the highest value of heat transfer. It was found that such data can be used to simulate wooden construction joints in future research.

Energy Losses or Savings Due to Air Infiltration and Envelope Sealing Costs in the Passivhaus Standard: A Review on the Mediterranean Coast

To obtain the Passivhaus Certificate or Passivhaus Standard (PHS), requirements regarding building envelope air tightness must be met: according to the n50 parameter, at a pressure of 50 Pa, air leakage must be below 0.6 air changes per hour (ACH). This condition is verified by following the blower door test protocol and is regulated by the ISO 9972 standard, or UNE-EN-13829. Some construction techniques make it easier to comply with these regulations, and in most cases, construction joints and material joints must be sealed in a complex way, both on façades and roofs and at ground contact points. Performing rigorous quality control of these processes during the construction phase allows achieving a value below 0.6 ACH and obtaining the PHS certification. Yet, the value can increase substantially with the passage of time: as windows and doors are used, opened, or closed; as envelope materials expand; with humidity; etc. This could result in significant energy consumption increases and losing the PHS when selling the house at a later point in time. It is therefore important to carefully supervise the quality of the construction and its execution. In this study, we focused on a house located in Sitges (Barcelona). The envelope air tightness quality was measured during four construction phases, together with the sealing of the joints and service ducts. The blower door test was performed in each phase, and the n50 value obtained decreased each time. The execution costs of each phase were also determined, as were the investment amortisation rates based on the consequent annual energy demand reductions. Air infiltration dropped by 43.81%, with the final n50 value resulting in 0.59 ACH. However, the execution costs—EUR 3827—were high compared to the energy savings made, and the investment amortisation period rose to a 15- to 30-year range. To conclude, these airtightness improvements are necessary in cold continental climates but are not applicable on the Spanish Mediterranean coast.

Study on impermeability of reinforced concrete wall with horizontal construction joints

The reinforced concrete (RC) water retaining tank walls with horizontal construction joints are prone to experiencing seepage under high hydrostatic pressure, which can affect the structural integrity and functionality. To evaluate the impermeability of construction joints with different improvement measures, the permeability test of concrete with and without horizontal construction joints was conducted. The test results show that the addition of Polypropylene fibers (PP fiber) and Cementitious Capillary Crystalline Waterproofing materials (CCCW) can improve the self-waterproofing ability of concrete. The impermeability at the construction joint is much lower than that of single-casting concrete. Moreover, applying CCCW to the water-facing surface of the construction joint can significantly enhance its impermeability. Then, two 1:2 scaled RC tank wall specimens were manufactured, with one wall of conventional concrete and the other wall of modified concrete. The impermeability tests of the typical single-casting and double-layer casting parts of the two wall specimens were carried out respectively. The experimental results show the RC tank wall with construction joint is prone to generate initial defects and seepage, making it difficult to achieve the design watertight requirements. The use of modified concrete materials and surface treatment in the relevant part can effectively improve the impermeability performance of the construction joint. Finally, the BP neural network was used to establish a prediction model between the impermeability of concrete and its material parameters and construction technology.

A multi-feature spatial–temporal fusion network for traffic flow prediction

The traffic flow prediction is the key to alleviate traffic congestion, yet very challenging due to the complex influence factors. Currently, the most of deep learning models are designed to dig out the intricate dependency in continuous standardized sequences, which are dependent to high requirements for data continuity and regularized distribution. However, the data discontinuity and irregular distribution are inevitable in the real-world practical application, then we need find a way to utilize the powerful effect of the multi-feature fusion rather than continuous relation in standardized sequences. To this end, we conduct the prediction based on the multiple traffic features reflecting the complex influence factors. Firstly, we propose the ATFEM, an adaptive traffic features extraction mechanism, which can select important influence factors to construct joint temporal features matrix and global spatial features matrix according to the traffic condition. In this way, the feature’s representation ability can be improved. Secondly, we propose the MFSTN, a multi-feature spatial–temporal fusion network, which include the temporal transformer encoder and graph attention network to obtain the latent representation of spatial–temporal features. Especially, we design the scaled spatial–temporal fusion module, which can automatically learn optimal fusion weights, further adapt to inconsistent spatial–temporal dimensions. Finally, the multi-layer perceptron gets the mapping function between these comprehensive features and traffic flow. This method helps to improve the interpretability of the prediction. Experimental results show that the proposed model outperforms a variety of baselines, and it can accurately predict the traffic flow when the data missing rate is high.

Validating a finite element model for rigid aircraft pavement load transfer against full scale testing

ABSTRACT Rigid aircraft pavements are generally comprised of unreinforced concrete slabs constructed on a bound or granular sub-base layer, over the natural or constructed subgrade or fill. Important to any rigid aircraft pavement design and construction are the joints between the concrete slabs. The joints control shrinkage cracks during curing, allow for thermal expansion and contraction during temperature cycles, they isolate concrete slabs from structural penetrations and importantly, provide load transfer between adjacent slabs. Load transfer is commonly modelled using finite element methods; however, any new model should be validated against observed physical events. Recently, full-scale testing was performed at the Federal Aviation Authority National Airport Pavement Testing Facility as part of Construction Cycle 8 (CC8), which investigated load transfer characteristics for a range of joint types. The results from CC8 tests provide up-to-date stress and strain values to validate any new finite element model. This paper presents the development of a finite element model to predict load transfer of a doweled construction joint, and its validation against CC8 test results. The model showed good agreement with CC8 test results, and now that it is validated, will be used to investigate innovative joint solutions for rigid aircraft pavements.

Curing characteristics and performance of a bio-based polyurethane engineered sealant with high bonding strength: Effect of R value and chain extender content

Polyurethane (PU) engineering sealants can be used to fill construction joints and pavement cracks with excellent practical results. However, traditional engineering sealants have the disadvantages of poor strength and raw materials that are not environmentally friendly. In this paper, a novel composition system of bio-based polyurethane engineering sealant was developed. The effects of the isocyanate/macroglycol molar ratio (nNCO/nOH, R value) for component A and the contents of amine chain extender (AME) on the curing characteristics and properties of the PU sealant were investigated using a series of experiments. Firstly, the curing process of the sealant was studied by Fourier transform infrared spectroscopy (FTIR) test, surface drying time test and gel time experiments. Secondly, the basic physical properties of the sealant were studied by tensile and hardness tests. And the water resistance of the sealant was judged. Then, the characteristics of molecular movement of polyurethane sealant were analyzed by dynamic mechanical analysis (DMA). The tensile cross-sections of the specimens were observed by scanning electron microscopy (SEM). Finally, the thermal stability of sealants was studied by thermogravimetric (TG) analysis. The results indicated that the material developed in this research can be used as a high-performance engineering sealant in actual projects. The increase in the R value and the decrease in AME content resulted in a longer curing process of the sealant. The rise of R value and AME content was able to raise the tensile strength, bonding strength and hardness of the sealant. The water resistance of the sealant was better. Also, the glass transition temperature (Tg) and storage modulus could also be increased and the thermal stability of the previous stage could be reduced by increasing the R value and AME content. Considering both the performance and construction requirements, the optimum R value and AME contents are recommended to be 2.1 and 1.4%, respectively.

Fine-tuning vision foundation model for crack segmentation in civil infrastructures

Large-scale foundation models have become the mainstream deep learning method, while in civil engineering, the scale of AI models is strictly limited. In this work, a vision foundation model is introduced for crack segmentation. Two parameter-efficient fine-tuning methods, adapter and low-rank adaptation, are adopted to fine-tune the foundation model in semantic segmentation: the Segment Anything Model (SAM). The fine-tuned CrackSAM shows excellent performance on different scenes and materials. To test the zero-shot performance of the proposed method, two unique datasets related to road and exterior wall cracks are collected, annotated and open-sourced, for a total of 810 images. Comparative experiments are conducted with twelve mature semantic segmentation models. On datasets with artificial noise and previously unseen datasets, the performance of CrackSAM far exceeds that of all state-of-the-art models. CrackSAM exhibits remarkable superiority, particularly under challenging conditions such as dim lighting, shadows, road markings, construction joints, and other interference factors. These cross-scenario results demonstrate the outstanding zero-shot capability of foundation models and provide new ideas for developing vision models in civil engineering.

Influence of Fire-Flame Temperature and Duration on the Behavior of Reinforced Concrete Beams with Construction Joints

Structural members' durability and strength depend on the member’s fire resistance. This study simulates the structural response of a reinforced concrete beam with a construction joint exposed to fire. The commercial finite element software ABAQUS was used to validate the laboratory findings. The testing program tested five reinforced concrete beams with the dimensions of (200x300x2700 mm), having identical reinforcing details and a concrete compressive strength (fc'=35 MPa). These beams had a 45° angled connection at the center. Four beams were exposed to fire flames at two temperature levels (600 °C and 800 °C) and for 1.0 and 2.0 hr. periods, respectively. The fifth beam is the control beam that was not exposed to fire. Laboratory results show that the worst exposure on the beam’s construction joint was at 800 °C with an exposure period of 2 hrs. This exposure reduces the bond between the joint’s two surfaces, creating a slipping effect in which disconnection occurs after loading. After 1 and 2 hours of exposure to fire at 600 °C, the residual flexural strength was 85% and 72% of that of the control beam, respectively. Whereas, beams exposed to fire for 1 and 2 hours at 800 °C showed flexural strengths lower than the control beam at 41% and 28%, respectively. Regarding the modulus of elasticity and compressive strength, they both showed residual values of (63.5, 59.2, 50.9, and 47%), and (28, 25, 19, and 16%), respectively.

Cover Picture: Geomechanics and Tunnelling 2/2024

AbstractLining stress controllers (LSC) have been developed as special supporting measure for tunnelling in zones with stress‐induced failure involving large ground volumes and large deformations. The shotcrete lining is divided into several segments by longitudinal construction joints. The purpose of this segmentation is to absorb large deformations occurring during tunnel driving in weak ground. LSC elements are installed into these deformation joints. These elements have a defined workload during compression so the primary lining is not damaged (Source: DSI Underground).

Comparing seismic performances of single-span RC frames with and without wing wall retrofitting by shaking table tests

It is necessary to retrofit existing single-span reinforced concrete (RC) frames which could not meet the current seismic codes due to lack of multiple seismic lines of defence. Adding wing wall is one of the retrofit method that can improve the redundancy of single-span RC frames. To study the effectiveness of single-span frames retrofitted by wing walls, shaking table tests were conducted on two 1:5 specimens to compare the seismic behaviour of single-span RC frames with and without wing wall retrofitting. First, a retrofit scheme for the frame using wing walls was selected. Two specimens—a single-span RC frame and an identical frame with a wing wall retrofit—were placed on the same shaking table board and tested simultaneously. Contrast tests were conducted for 20 earthquake cases. The main conclusions are as follows: (1) Adding wing walls to a single-span frame in bi-direction is a reasonable strengthening scheme. (2) For the single-span frame without retrofitting, cracks appeared in the early stages and rapidly developed, forming plastic hinges at the ends of the beams and columns. For the single-span frame with retrofitting, cracks first appeared in the construction joints between the wing walls and beams, and then extended to wing walls and beams. The test phenomena indicate that adding wing walls to a single-span frame can increase system redundancy, and act as the first anti-seismic line of defence. (3) From the measured data, it is shown that adding wing walls to a single-span frame can improve its seismic capacity and control the lateral deformation. The peak floor displacement response of the retrofitted frame reduced by 30%–40% compare with that of the frame without retrofitting. (4) When input PGA was 0.15g (design based earthquake), slight damage occurred to the frame retrofitted by wing wall, while damage of the frame without retrofitting was moderate. When input PGA was 0.30g (rare earthquake), moderate damage occurred to the frame retrofitted by wing wall, while damage of frame without retrofitting was severe. Therefore, adding wing walls is an effective method for retrofitting single-span RC frame structures.