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Monolithic precast concrete frame structures have been promoted and developed in recent years. Owing to material deterioration and a weaker structural integrity, monolithic precast concrete frame structures may suffer from insufficient seismic capacity as service time increases. A typical joint of monolithic precast concrete frame structure is studied in this paper. The purpose of this paper is to perform numerical modeling of the typical joint subjected to low cyclic load at different ages and analyze the hysteretic behavior reduction with ages under common atmosphere environment.

Existing un-carbonated concrete, carbonated concrete and corroded rebar are all considered as deterioration factors for the typical joint, whose constitutive models are introduced into the finite element model to study. Moreover, time-dependent constitutive model of existing un-carbonated concrete and mechanical model of bond between precast and cast-in-place concrete are established on the basis of existing experimental data. Then, finite element method is used to investigate the seismic property reduction of the typical joint, where nonlinear springs are set to simulate bonding between precast and cast-in-place concrete.

Analyzing the results, the reduction of reaction force from skeleton curves of the joint is significant in the first 30 years of service time, and slows down after 30 years. Besides, the ductility, secant stiffness and equivalent viscous damping coefficient of the typical joint remain almost unchanged in the first decade, but decrease obviously after 10 years.

The originality of the paper consists in the following. The time-dependent constitutive model of existing un-carbonated concrete is established and used in finite element method. Besides, bonding between precast and cast-in-place concrete is considered using nonlinear springs. There is a reference value for the seismic performance assessment of existing monolithic precast concrete frame structures.

Textile reinforced concrete (TRC) has excellent bearing capacity and anti-crack and corrosion resistance capacity, which are suitable for strengthening concrete structure under harsh environments.

In this thesis, flexural properties of RC beams strengthened with TRC under chloride wet–dry cycles were studied and the effects of the concentration of the salt solution, number of wet–dry cycles, bending stress level and TRC form were considered. Four-point bend loading mode was adopted for the step-loading procedure.

As the number of wet–dry cycles was relatively few, the trend of the yield and ultimate load with the increasing concentration of salt solution and wet–dry cycles were not obvious. However, the beams under high sustained bending stress level (0.5) had a decrease in the bearing capacity and an increase in mid-span deflection because of the larger degree of the corrosion of steel bars and the weaker bond capacity between the steel bar and concrete. Besides, there was little difference between the precast TRC plate and the casting TRC on beams in terms of the capacity of anti-crack, bearing and deflection.

In this paper, preliminary work has been carried out, but some of the factors were not comprehensive considered, which are inevitable. As the time of dry–wet cycles was short and TRC layer had good anti-crack and anti-permeability performance, smaller chloride ions’ penetration resulted in the corrosion ratio of steel bars to be lower.

It should be noted that under high corrosion rates of the reinforcement, the whole TRC strengthening layer might be spalled off if only the strengthening form at the beam bottom is used, and thus the U-type strengthening form could be considered, which means that the beam is strengthened at both the bottom and side surfaces.

This research only considers the flexural performance of the beams strengthened with TRC in conventional environment, and there is little research on the TRC-strengthened beam under corrosion environment. On the basis of previous research, this paper carried out the experimental study on beams strengthened with TRC under chloride wet–dry cycle environment, and the effects of the concentration of the salt solution, number of wet–dry cycles, bending stress level and TRC form were considered.

The purpose of this paper is to show that the growing global trend of quality assurance indicates the potential of precast concrete (PC) to improve construction quality and productivity, reduce wasteful construction, and achieve design standardization and to accelerate construction time. However, its current approach for dynamic characteristics, such as stiffness and displacement on beam-column connection system design, is not effective in achieving the required quality and operational requirements.

A design tool based on the literature and data analysis in product planning and safety is proposed for the practice of PC building construction.

The results reveal the need for improvement of PC building performance in the construction industry, especially for the beam-column connection system. The issues include improper design, improper specification and defective concrete and steel components compared to other manufacturing methods.

A novel and sophisticated technique based on physical internet-enabled building information modeling (PI-BIM) is proposed to improve the planning process and safety for PC buildings in Malaysia.

Damage to reinforced concrete (RC) structural elements is inevitable. Such damage can be the result of several factors, including aggressive environmental conditions, overloading, inadequate design, poor work execution, fire, storm, earthquakes etc. Therefore, repairing and strengthening is one way to improve damaged structures, so that they can be reutilized. In this research, the use of an ultra high-performance fibre-reinforced concrete (UHPFRC) layer is proposed as a strengthening material to rehabilitate damaged-RC beams. Different strengthening schemes pertaining to the structural performance of the retrofitted RC beams due to the flexural load were investigated.

A total of 13 normal RC beams were prepared. All the beams were subjected to a four-point flexural test. One beam was selected as the control beam and tested to failure, whereas the remaining beams were tested under a load of up to 50% of the ultimate load capacity of the control beam. The damaged beams were then strengthened using a UHPFRC layer with two different schemes; strip-shape and U-shape schemes, before all the beams were tested to failure.

Based on the test results, the control beam and all strengthened beams failed in the flexural mode. Compared to the control beam, the damaged-RC beams strengthened using the strip-shape scheme provided an increase in the ultimate load capacity ranging from 14.50% to 43.48% (or an increase of 1.1450 to 1.4348 times), whereas for the U-shape scheme beams ranged from 48.70% to 149.37% (or an increase of 1.4870–2.4937 times). The U-shape scheme was more effective in rehabilitating the damaged-RC beams. The UHPFRC mixtures are workable, as well easy to place and cast into the formworks. Furthermore, the damaged-RC beams strengthened using strip-shape scheme and U-shape scheme generated ductility factors of greater than 4 and 3, respectively. According to Eurocode8, these values are suitable for seismically active regions. Therefore, the strengthened damaged-RC beams under this study can quite feasibly be used in such regions.

Observations of crack patterns were not accompanied by measurements of crack widths due to the unavailability of a microcrack meter in the laboratory. The cost of the strengthening system application were not evaluated in this study, so the users should consider wisely related to the application of this method on the constructions.

Rehabilitation of the damaged-RC beams exhibited an adequate structural performance, where all strengthened RC beams fail in the flexural mode, as well as having increment in the failure load capacity and ductility. So, the used strengthening system in this study can be applied for the building construction in the seismic regions.

Aside from equipment, application of this strengthening system need also the labours.

The use of sand blasting on the surfaces of the damaged-RC beams, as well as the application of UHPFRC layers of different thicknesses and shapes to strengthen the damaged-RC beams, provides a novel innovation in the strengthening of damaged-RC beams, which can be applicable to either bridge or building constructions.

To predict the real behavior of the full-scale model using a scale model, optimized simulation should be achieved. In reinforced concrete (RC) models, scaling can be substantially more critical than in single-material models because of multiple reasons such as insufficient bonding strength between small-diameter steel bars and concrete, and excessive aggregate size. Overall, there is a shortfall of laboratory and field-testing studies on the behavior of secant pile walls under lateral and axial loads. Accordingly, the purpose of this study is to investigate the validity and the performance of the 1/10th scaled RC secant pile wall under the influence of different types of loading.

The structural performance of the examined models was evaluated using two types of tests: bending and axial compression. A self-compacting concrete mix was suggested, which provided the best concrete mix workability and appropriate compressive strength.

Under axial and bending loads, the failure modes were typical. Where the plain and reinforced concrete piles worked in tandem to support the load throughout the loading process, even when they failed. The experimental results were relatively consistent with some empirical equations for calculating the modulus of elasticity and critical buckling load. This confirmed the validity of the proposed model.

According to the analysis and verification of experimental tests, the proposed 1/10th scaled RC secant pile model can be used for future laboratory purposes, especially in the field of geotechnical engineering.

Environmental issues caused by the production of Portland cement have led to it being replaced by waste materials such as fly ash, which is more economical and safer for the environment. Also, fly ash is a material with sustainable properties. Therefore, this paper aims to focus on the development of sustainable construction materials using 100% high-calcium fly ash and potassium hydroxide (KOH)-based alkaline solution and study the engineering properties of the resulting fly ash-based geopolymer concrete. Laboratory tests were conducted to determine the mechanical properties of the geopolymer concrete such as compressive strength, flexural strength, curing time and slump. In phase I of the study, carbon nanotubes (CNTs) were added to determine their effect on the strength of the geopolymer mortar. The results derived from the experiments indicate that mortar and concrete made with 100% fly ash C require an alkaline solution to produce similar (comparable) strength characteristics as Portland cement concrete. However, it was determined that increasing the amount of KOH generates a considerable amount of heat causing the concrete to cure too quickly; therefore, it is notable to forming a proper bond was unable to form a stronger bond. This study also determined that the addition of CNTs to the mix makes the geopolymer concrete tougher than the traditional concrete without CNT.

Tests were conducted to determine properties of the geopolymer concrete such as compressive strength, flexural strength, curing time and slump. In Phase I of the study, CNTs were studied to determine their effect on the strength of the geopolymer mortar.

The results derived from the experiments indicate that mortar and concrete made with 100% fly ash C require an alkaline solution to produce the same strength characteristics as Portland cement concrete. However, it was determined that increasing the amount of KOH generates too much heat causing the concrete to cure too quickly; therefore, it is notable to forming a proper bond. This study also determined that the addition of CNTs to the mix makes the concrete tougher than concrete without CNT.

This study was conducted at the construction engineering and management concrete laboratory at North Dakota State University in Fargo, North Dakota. All the experiments were conducted and analyzed by the authors.

This study aims to further study the fire resistance of prefabricated concrete beam-column joints with end-plate connection. This paper aims to analyze the fire resistance of this joint in prefabricated reinforced concrete frame structure (PRCS).

First, the accuracy of the model is verified by using the test data. Based on this, a refined finite element model of PRCS structure with two stories and two spans is established. The influence of four working conditions with different fire floors (positions) and different axial compression ratios on the deformation, failure and fire resistance of PRCS structure are analyzed.

The results show that under the four working conditions, the fire resistance of the PRCS structure under Condition 1 and Condition 2 is smaller. It shows that the beam deformation develops slowly in PRCS structure under four kinds of fire positions, and the large displacement emerges 60 min later, which is poles apart from that of prefabricated beam column members. With the increase of the fire time, the material is damaged and deteriorated, which leads to the eccentricity of the axial load, so that the column top appears large lateral displacement. Under the Conditions 1 and 3, the lateral displacement of the column gradually decreases as the axial compression ratio rises.

It is found that there is a distinct lack of researching on the fire resistance of prefabricated joints, and the existed research studies are limited to the fire resistance of members. Thus, it is necessary to strengthen the first floor and side column design of prefabricated frame structure.

Prefabricated columns connected by grouted sleeves are increasingly used in practical projects. However, seismic fragility analyses of such structures are rarely conducted. Seismic fragility analysis has an important role in seismic hazard evaluation. In this paper, the seismic fragility of sleeve connected prefabricated column is analyzed.

A model for predicting the seismic demand on sleeve connected prefabricated columns has been created by incorporating engineering demand parameters (EDP) and probabilities of seismic failure. The incremental dynamics analysis (IDA) curve clusters of this type of column were obtained using finite element analysis. The seismic fragility curve is obtained by regression of Exponential and Logical Function Model.

The IDA curve cluster gradually increased the dispersion after a peak ground acceleration (PGA) of 0.3 g was reached. For both columns, the relative displacement of the top of the column significantly changed after reaching 50 mm. The seismic fragility of the prefabricated column with the sleeve placed in the cap (SPCA) was inadequate.

The sleeve was placed in the column to overcome the seismic fragility of prefabricated columns effectively. In practical engineering, it is advisable to utilize these columns in regions susceptible to earthquakes and characterized by high seismic intensity levels in order to mitigate the risk of structural damage resulting from ground motion.

Malaysia’s industrialised building system (IBS) has been increasingly adopted for sustainable development by the country’s construction industry. However, although it has been used for commercial building projects, its application to sustainable infrastructure development has been limited to date. This study aims to examine the drivers and challenges involved.

A preliminary conceptual framework was initially developed based on a systematic literature review. Semi-structured interviews involving 20 participants were undertaken to gain insightful thoughts from the construction practitioners to discover the perception towards IBS application in the construction industry, the applicability of IBS, particularly in infrastructure projects, the strategies of IBS delivery and the sustainable potential of its application. A two-round Delphi study was conducted with 15 experienced and knowledgeable panellists to further identify, verify and prioritise factors developed from the literature review and interview findings. Then, the results were synthesised and triangulated to demonstrate a holistic insight.

The results show the main drivers to be better productivity, quality, environmental, safety and health, constructability design and cost, policy and requirements, with the main challenges being project planning and cost-related issues, inexperience and industry capacity.

The study’s main contribution is in systematically determining the practical implications involved in applying the IBS to sustainable infrastructure developments in Malaysia and other similar developing countries.

In order to reduce the impact of bridge construction on traffic under the bridge, the construction of bridges for some important traffic nodes usually adopts the swivel construction method. The spherical hinge is a rotating mechanism located between the bottom of the pier and the bridge cap, and is subjected to tremendous vertical pressure. According to the mechanical characteristics of the spherical hinges, this paper applies the ultra-high performance concrete (UHPC) material to the spherical hinge. The spherical hinge is subjected to a compression test to test its mechanical behavior. This paper aims to discuss this issue.

In order to test the mechanical behavior of the UHPC spherical hinge, multiple sets of 100 mm UHPC spherical hinge specimens were prefabricated. Through the universal testing machine to measure the compressive strength of specimens, draw the force-displacement curve to analyze the failure mechanism and establish the stress calculation formula of the spherical hinge at each point along the radial direction.

Through the test, the compressive strength of UHPC spherical hinge is obtained, and the influencing factors of UHPC spherical hinge strength are found: reducing water–cement ratio, increasing steel fiber content and length and changing steel fiber arrangement direction can effectively improve the compression strength of UHPC spherical hinge.

For the first time, UHPC materials were applied to the spherical hinge structure, the UHPC spherical hinge diameter is 1/3 of the diameter of the reinforced concrete spherical hinge, which is equivalent to the diameter of the steel spherical hinge. By applying the UHPC spherical hinge, the manufacturing cost is reduced, the process is simple, and the construction difficulty is reduced.