Engineering Journal of Research and Development

LATERAL DISPLACEMENT OF HIGH-RISE BUILDINGS DURING CONSTRUCTION USING STAGED CONSTRUCTION ANALYSIS

Nattapat Wongpakdee — 2026-09-30

This study investigates the lateral displacement of a 30-story reinforced concrete building (24×24 m) under construction dead load. Wind and earthquake loads are excluded. The aim is to evaluate the effects of the construction sequence and of the shear-wall layout (symmetric and asymmetric). A three-dimensional structural model was developed using linear-elastic material behavior and including P–Δ effects. The results from instantaneous analysis (IA) were compared with those from staged construction analysis (SCA) for both symmetric and asymmetric lateral systems. IA predicts a monotonic increase in lateral displacement with height, reaching 66.8 mm at the top floor. In contrast, SCA gives a maximum of 17.5 mm at the 21st floor. The asymmetric case shows much larger displacement than the symmetric case (17.5 mm versus less than 1 mm). The displacement is largest in the direction of lower overall lateral stiffness. This response is mainly a one-directional sway rather than torsion. The maximum inter-story drift ratio is about 0.45/500, well within the typical serviceability limit (1/400 to 1/500). These findings indicate that both the location and magnitude of peak deformation during construction can differ from those predicted by instantaneous analysis. It can be concluded that staged construction analysis is appropriate for evaluating deformation during construction. This is especially true for high-rise buildings with asymmetric lateral systems, where the maximum displacement may not occur at the top floor.

ENGINEERING PROPERTIES OF CEMENT-EUCALYPTUS ASH GRAVEL COLUMN REINFORCED WITH PLASTIC BOTTLE FIBERS

Tanakit Phoopradit — 2026-09-30

Construction of embankments on soft clay foundations often encounters excessive settlement and low stability due to the low shear strength and high compressibility of the soil. Ground improvement techniques using columns such as concrete columns, soil–cement columns, and gravel columns are commonly adopted to enhance subsoil performance. However, these columns generally provide strength higher than required for embankment applications, resulting in increased construction costs and resource consumption. This study proposes the development of a semi-rigid column by integrating the characteristics of flexible and rigid columns, namely a eucalyptus ash–cemented gravel column reinforced with plastic bottle fibers. The objective is to investigate its engineering properties for construction applications while simultaneously reducing material costs and environmental impacts. Ordinary Portland cement was partially replaced with eucalyptus ash, a by-product from biomass power plants with suitable chemical composition for pozzolanic reactions, to enhance bonding performance and reduce cement consumption. In addition, recycled plastic bottles were processed into fibers to reinforce the column material, aiming to improve crack resistance and mechanical performance while mitigating plastic waste. The materials consisted of coarse aggregates with sizes of 4.76–9.51 mm and 9.51–19.00 mm, hydraulic cement content of 340 kg/m³, and a water–cement ratio of 0.32. Cement was replaced with eucalyptus ash at 5, 10, 15, 20, and 25% by weight. Recycled plastic fibers with a width of 2 mm and length of 70 mm were incorporated at 0.5, 1.0, 1.5, and 2.0% by volume. Tests were conducted to determine porosity, compressive strength, splitting tensile strength, and coefficient of permeability at curing ages of 28 and 90 days. The results showed that aggregate size, eucalyptus ash content, and plastic fiber content all affected the strength and drainage capacity of the columns. Well-graded aggregate provided the highest strength due to better particle arrangement, while single-sized aggregate provided better porosity and water permeability. Replacing cement with 10% eucalyptus ash resulted in the highest strength, along with the lowest porosity and coefficient of permeability. Similarly, a plastic fiber content of 1.0% resulted in the highest strength, along with the lowest porosity and coefficient of permeability. These findings can serve as a guideline for designing the mix proportions of eucalyptus ash–cemented gravel column reinforced with plastic bottle fibers to suit specific application objectives—whether emphasizing strength or drainage performance—thereby promoting efficient resource utilization and reducing environmental impact.

BEHAVIOR OF WIDE-FLANGE STEEL BEAMS STRENGTHENED WITH CFRP PLATES UNDER BENDING TEST

Norawit Monki่j — 2026-09-30

This study investigates behavior of wide-flange steel beams strengthened with CFRP plates under bending test. A total of six beam specimens were tested under four-point bending. The span length of the test beams was 1800 mm. The variables considered in this study included the number of CFRP layers, the use of end anchorage for the CFRP plates, and the installation of steel stiffeners to control the failure modes of the beams. The test results show that strengthening the bottom flange of the beam with CFRP plates significantly increases the load-carrying capacity and effectively reduces beam deflection in the elastic range. However, the use of CFRP plates alone may lead to local buckling of the top flange or the web before the beam reaches the plastic deformation stage. The installation of steel stiffeners can reduce local buckling and further improve the load-carrying capacity. Meanwhile, the use of end anchorage for the CFRP plates helps prevent premature debonding, resulting in significant improvements in both the load-carrying capacity and the ductility of the beams.

INTERNAL FACTOR AFFECTING THE CONSTRUCTION MANAGEMENT OF LARGE – SCALE AIRPORT BUILDINGS

Worawoot Chetnarong — 2026-09-30

This research investigates the internal factors specifically Personal Factors, Construction Contract Management Factors, and Project Resource Factors—that are perceived to impact the construction management of Large-Scale Airport Building Projects across three dimensions: Work Delays, Cost Management, and Work Quality. Conducted using a quantitative survey of N = 73 experienced professionals involved in the SAT-1 project, the study findings are structured as follows: 1) Descriptive Ratings: Internal factors overall were perceived as having a high impact on construction management dimensions, with Work Delays receiving the highest average impact rating ( = 3.89), where Contract Management emerged as the highest-ranked internal variable. 2) Group Comparisons (ANOVA): A One-Way ANOVA revealed no statistically significant differences in perceptions across educational backgrounds and stakeholder groups (p > 0.05). However, professional experience revealed a statistically significant difference regarding how personal factors affect work delays and cost management (p = 0.050). 3) Correlation Analysis (Pearson's, r): Correlation analyses demonstrated strong positive associations among the internal factors across the outcome dimensions, most notably between Cost Management and Work Quality (r = 0.850, p < 0.001), Work Delays and Work Quality (r = 0.810, p < 0.001). The findings provide an empirical baseline of perceived associations within a multi-contract Mega-Project context, offering actionable risk-management recommendations for future aviation infrastructure expansions.

COST COMPARISON OF CONVENTIONAL AND SEISMIC-RESISTANT FOUNDATION SYSTEMS: A CASE STUDY OF THE STATE AUDIT OFFICE BUILDING

Tewakun Chankampom — 2026-09-30

This research aims to compare the construction costs of conventional foundation systems and foundations designed to resist seismic forces, using the Office of the Auditor General building as a case study. The study employs a quantitative analysis based on construction drawings combined with engineering-based cost estimation. Four design alternatives were considered: (1) the conventional foundation, (2) increasing the foundation size, (3) increasing reinforcement, and (4) connecting the grade beams to the foundations. The results showed that the conventional foundation had the lowest cost at THB 17.16 million, while increasing the foundation size resulted in the highest cost at THB 20.53 million, representing an increase of 19.64%. The alternatives involving increased reinforcement and connecting grade beams to the foundations resulted in cost increases of 9.43% and 8.16%, respectively. Overall, the construction costs of the seismic-resistant foundation alternatives increased by 8.16-19.64%. Although the design of seismic-resistant foundations increases initial construction costs, the alternatives involving increased reinforcement and connecting grade beams to the foundations resulted in lower cost increases than increasing the foundation size within the scope of this case study. The findings can serve as supporting information for decision-making in foundation design considering seismic conditions, particularly for public-sector building projects