Journal of Structural Engineering

The number of studies on ultrahigh-performance concrete (UHPC) or ultrahigh-performance fiber-reinforced concrete (UHP-FRC) for more resilient and sustainable reinforced concrete (RC) structures has rapidly increased in recent years due to the superior mechanical and durability properties of UHPC. The application of UHPC as a replacement for conventional concrete materials in various RC elements necessitates a thorough understanding of the structural behavior of the reinforced UHPC (R/UHPC) components under various types of loadings. This paper presents a systematic review of the state-of-the-art developments in R/UHPC elements. It addresses various topics including beams, columns, beam–column joints, shear walls, bridges, structural retrofitting, and applications such as seismic and impact. Due to the ultrahigh tensile, compressive, and bond strengths, unique strain-hardening behavior, and ductility of UHPC, R/UHPC structures may exhibit substantially different behavior than conventional RC structures at both the component and system levels. This implies that particular attention must be paid when design and analysis approaches for conventional RC elements are applied to R/UHPC elements, and suggests that developing new design philosophies is warranted to take advantage of UHPC’s unique mechanical properties. The present paper summarizes the developments in analysis and design approaches for R/UHPC elements under axial forces, shear forces, and bending moments, and highlights the advantages and limitations of these approaches. Important design considerations for effectively utilizing UHPC in structural elements are also suggested. In addition to normal-strength steel reinforcing bars, the potential for reinforcing UHPC with high-strength steel bars, fiber-reinforced polymer components, and structural steel shapes is discussed based on the results of pioneering studies. Finally, this paper identifies challenges and suggests future directions for research on UHPC in structural engineering.

Wide-flange (W-shape) steel members are known to have initial geometric imperfections. A three-dimensional noncontact laser-scanning technique is used to measure the imperfection fields in fourteen specimens. A spectral approach that models the imperfections in each plate of the W-shape member as a two-dimensional random field is employed to characterize the imperfections and capture the existence of periodicity in them. The proposed modeling approach along with the traditional modal approach are used to study the sensitivity of numerical models to initial geometric imperfections. The studies are conducted at both member and system levels using a set of column and frame models employing deep W-shape columns under combined axial and lateral cyclic loading. It is shown that although initial geometric imperfections can, in certain situations, influence column buckling behavior as well as frame collapse mode, their effect on nonlinear cyclic behavior is generally small and inconsistent. Based on this finding, it is recommended that initial geometric imperfections need not be incorporated in high-fidelity numerical models of W-shape members subjected to combined axial and cyclic lateral loads. However, this is conditioned upon the use of a computational platform with sufficient numerical precision to capture the early small deformations that promote geometric nonlinearity in the response.

Cross-laminated timber (CLT) is an engineered wood product offering several advantages for wood utilization in midrise and tall buildings. However, moisture intrusion poses significant risks since it can affect the durability of CLT structural members and their connections. There has been much research on connection performance to understand their seismic response. However, the impact of moisture on the performance of CLT connectors is less understood. Cyclic tests were conducted on a series of CLT shear wall-to-diaphragm L-bracket (angle bracket) connections after subjecting them to a wetting and redrying cycle. The study includes three exposure durations and four wood species (Douglas fir, Southern yellow pine, Norway spruce, and spruce-pine-fir) to investigate the effect of moisture exposure on the connection performance. The performance was characterized in terms of strength, stiffness, and energy dissipation. In addition, two existing engineering force-displacement models were fitted to the experimental data. Results indicate that the changes due to wetting and redrying cycling were not statistically significant for the load-carrying capacity and stiffness. In contrast, a statistically significant decrease in the total energy dissipation capacity was observed.

This paper studies the rotational behavior of beam-to-column bolted connections in bamboo scrimber structures. Three types of beam-to-column connections, including bolted connections with outer-clamping steel plates, bolted connections encased with T-shaped steel plates, and bolted connections encased with double L-shaped steel plates, were designed and tested under monotonic or reversed cyclic loads. The influence of bolt arrangement on the mechanical properties was also studied. Failure of the connections was mainly caused by cracking of the adhesive interface near the bolt at the tensile side of the beam, which was a weak point that needs further attention. The elastic stiffness, capacities, ductility coefficient, and energy dissipation capacity of the T-steel connections improved compared with the I-steel connections. The load-carrying capacities of the connections were calculated according to common standards. Results showed that for the I-, T-, and double L-steel connections, the different standards had different safety margins.

This paper focuses on the simulation of irregular stone masonry by the lattice discrete particle model (LDPM), which simulates the fracture and failure behavior of quasi-brittle heterogeneous materials by modeling the interaction among coarse material heterogeneities. LDPM is formulated at the length scale of the masonry stones whose interaction is described through constitutive equations featuring softening in tension and strain hardening in compression. The numerical results relevant to diagonal compression tests show that the intrinsic stochastic character of LDPM can quantify the variation of the mechanical properties of irregular masonry resulting from random stone size and stone-size distribution. Furthermore, the paper presents an analysis of the size effect on irregular stone masonry structures. This was obtained by simulating the shear behavior of geometrically similar samples of different sizes. The simulations demonstrate that increasing structural size leads to a significant reduction of both structural strength and structural ductility. The magnitude of the predicted size effect suggests that, contrary to typical experimental results on reduced size samples, real irregular masonry structures must be considered as perfectly brittle.

A strong mainshock may cause several aftershocks within a short interval. These aftershocks can make buildings damaged during the mainshock more vulnerable to collapse. Hence, it is critical to study the seismic responses of a structure during aftershock events following a major shock. The focus of this work was to investigate the seismic fragility of an emerging high-performance seismic-resistant system—the self-centering energy-absorbing dual rocking core (SEDRC) system—considering mainshock–aftershock sequences, and to compare SEDRC with traditional systems. First, three- and six-story SEDRC systems were designed following the direct displacement-based design method to show comparable maximum interstory drifts compared with those of the three- and six-story benchmark buckling-restrained braced frames (BRBFs), respectively, under the design-basis earthquake excitations. Second, 30 as-recorded mainshock–aftershock sequences were selected. The dynamic analyses and incremental dynamic analyses (IDAs) were conducted to study the seismic responses of the four buildings with the mainshock inputs alone and the mainshock–aftershock sequence inputs. The analysis results show that the designed SEDRC systems and BRBFs can obtain comparable performance in limiting the maximum interstory drifts (MID) responses, whereas the SEDRC systems are more efficient in limiting the maximum residual interstory drifts (MRD). Moreover, the SEDRC systems perform much better than BRBFs in resisting structural collapse. As expected, the aftershocks would increase the MID, but may increase or decrease the MRD of the SEDRC systems and BRBFs. Finally, the seismic fragilities of the designed systems were further investigated on the basis of the results from the IDAs in a probabilistic framework using a joint probability density function with the consideration of both MID and MRD. The advantages of the SEDRC systems in achieving excellent seismic collapse-resistant and self-centering capacity were explored through probabilistic analyses.

To advance understanding of the multihazard performance of midrise cold-formed steel (CFS) construction, a unique multidisciplinary experimental program was conducted on the Large High-Performance Outdoor Shake Table (LHPOST) at the University of California, San Diego (UCSD). The centerpiece of this project involved earthquake and live fire testing of a full-scale 6-story CFS wall braced building. Initially, the building was subjected to seven earthquake tests of increasing motion intensity, sequentially targeting service, design, and maximum credible earthquake (MCE) demands. Subsequently, live fire tests were conducted on the earthquake-damaged building at two select floors. Finally, for the first time, the test building was subjected to two postfire earthquake tests, including a low-amplitude aftershock and an extreme near-fault target MCE-scaled motion. In addition, low-amplitude white noise and ambient vibration data were collected during construction and seismic testing phases to support identification of the dynamic state of the building system. This paper offers an overview of this unique multihazard test program and presents the system-level structural responses and physical damage features of the test building throughout the earthquake-fire-earthquake test phases, whereas the component-level seismic behavior of the shear walls and seismic design implications of CFS-framed building systems are discussed in a companion paper.

Complementing a companion paper that summarizes the building global response and physical damage of a midrise cold-formed steel (CFS) framed building during an earthquake and postearthquake fire test program, this paper focuses on understanding the seismic behavior of the shear walls utilized in the building system during this test program. In contrast to shear walls tested in an isolated configuration, the shear walls within the full-scale test building were constructed and tested under real-world kinematic constraints and dynamic loading environments. The shear walls located at various planar and vertical locations of the test building were instrumented with a dense array of analog sensors to monitor the shear wall local responses. In this study, the shear wall local responses are correlated with the global responses of the building to advance understanding regarding the behavioral characteristics of individual shear walls and in particular the interactions of the shear walls as part of the lateral-load-resisting system. Important seismic design parameters are inferred from the measured building response using a parameter optimization strategy. Their implications associated with the seismic design of CFS wall-framed structural systems are discussed in relation to code provisions and design guidelines.

This study develops the probabilistic seismic response and capacity models for the broad collection of standard pile designs that are routinely incorporated into bridges in California. A review of the state bridge inventory indicates considerable variations in design details for different standard pile types used across multiple eras. For each pile type, fiber-section-based pile models attached with $p\text{-}y$ soil springs are built to incorporate nonlinear behaviors of soil materials, a wide array of heterogeneous soil profiles, full-range damage states of piles, and realistic connection details between piles and footings (i.e., pile caps). Moreover, force-displacement responses of pile-soil systems under a large number of pushover analyses are regressed as response models consisting of five parameters [termed as response five parameter (R5P) models], which can capture all essential behaviors of laterally-loaded piles. Capacity damage states and limit state models are defined for different pile types by linking pile global responses to fiber-scale material behaviors at plastic hinge locations. Procedures are further provided to expand R5P models to pile foundation models at the regional scale, taking into account the pile group effect and capacities of pile cap backfills. R5P models for all distinct pile types are further summarized in an Excel workbook to facilitate their practical implementations. In general, this study provides a comprehensive and consistent set of response and capacity models to quantify the seismic damage potential of regional pile foundations, as well as to capture their dynamic interplays with other crucial bridge components, such as columns and abutment components. The proposed pile models are expected to significantly enhance the existing modeling capability toward improved seismic risk assessment of California’s bridge infrastructure.

In this paper, a series of full-scale wind tunnel tests are conducted to study the vortex-induced vibration (VIV) of the steel tubes connected with C-shaped bolted joints. The dynamic properties of VIV responses of the steel tubes are analyzed and discussed in terms of probability density functions (PDFs) and power spectral density (PSD) functions. Based on the wind tunnel test results, a new empirical formula is derived to estimate the VIV critical wind speed of the tube with C-shaped joints, and an improved model is developed to predict the maximum VIV response of the steel tube. The proposed models are further validated through an independent wind tunnel test. In order to suppress excessive VIV responses of steel tubes, a passive vibration control approach is employed by installing a discrete cross-fin spoiler (DCFS) in various designs on the testing tubes. Key design factors of the DCFS, which are related to the VIV suppression effectiveness, are studied through wind tunnel tests, and the relatively optimal design of DCFS is recommended for VIV mitigation.

This paper puts forward a new kind of joint called plate-insert welded tubular joint that is used in long-span prestressed spatial structures. It is composed of one inserted plate, one major member, and several minor members. The plate is inserted through a major member, and the minor members intersect the major member. The static performance of cooperative work between the inserted plate, major member, and minor members are studied by numerical analysis using ABAQUS and Ansys, from which the elastic ultimate bearing capacity of the joint are obtained. The multigroup of geometric parameters are set to establish a number of finite-element models for parametric analysis to obtain the effect rule of different inserted-plate length parameters on bearing capacity. Then a new design method of the joint is put forward on the basis of the analysis. From the joint design example of the second stage of the Tianjin Binhai International Exhibition, the reliability of the method is verified using a combination of numerical and experimental studies.

Nonlinear analyses of structures under dynamic excitation are becoming increasingly important in structural design and performance evaluation, but large computational effort is the main factor that limits their application. Because nonlinearity is commonly confined within small regions, many studies have been devoted to improving the efficiency of solving such local nonlinear problems by maintaining the structural stiffness elasticity and simulating the effects of local nonlinearity through fictitious nonlinear forces or local modification of the elastic structural response. For dynamic analysis, the nature of the stiffness matrix determines the formulation of the widely used Rayleigh damping; as a result, these local nonlinear analysis methods often use elastic stiffness-based Rayleigh damping models. However, such a damping model can generate unexpected artificial damping forces for inelastic systems and consequently produce inaccurate or even invalid results. Although a tangent stiffness–based Rayleigh damping model has been proven to be a reasonable basis for performing highly accurate dynamic analyses, this type of damping model has difficulty achieving direct compatibility with local nonlinear analysis methods. The present research focuses on the implementation of a tangent stiffness–based Rayleigh damping model for use in efficient local nonlinear analysis methods developed based on the Woodbury formula, which can calculate the structural inelastic behavior by updating the elastic solution rather than by updating the stiffness. By representing tangent stiffness–based Rayleigh damping as a low-rank perturbation to the elastic stiffness-based damping matrix, this study derives a modified dynamic Woodbury formula in which an additional influence coefficient is introduced to reflect the effects of local nonlinearity on the structural damping properties. Moreover, to overcome the potential solution difficulty caused by abrupt changes in the damping forces in certain steps and further improve the efficiency of the proposed method, a variable time step solution scheme that can meet the computational requirements of the Woodbury formula is presented. Verifications demonstrate the validity and high efficiency of the proposed method.

Blast-loaded structures respond dynamically to impulsive loads generated by an explosion. Individual components must possess adequate flexural and sectional shear capacity to survive such extreme loads. Unlike static loads, blasts can cause a unique limit state known as direct shear failure, which occurs early in the response history of a blast-loaded member. While various researchers have observed this phenomenon in past testing, the fundamental mechanics underlying this behavior are not completely understood. Multiple analysis approaches for capturing direct shear behavior of blast-loaded members have been proposed in the research literature, suggesting that further study is needed to understand this phenomenon. In this paper, direct shear response is explored in detail, demonstrating that this behavior originates from high-frequency contributions that are often neglected in modal analyses or misrepresented as a feature of traditional flexural response in single-degree-of-freedom analyses.

Bolted connections are commonly used for attaching structural elements in various civil and mechanical engineering applications. Despite their popularity, various studies raised concerns over the adequacy of design provisions in capturing connection strength. Design provisions to accurately predict connection strength could be refined through experimental tests and/or the use of highly nonlinear analysis that can simulate stress redistribution and ductile fracture in the connections. Recently, an effective numerical method for accurately predicting ductile fracture of bolted connections under any stress state was proposed and validated. In this study, using the validated numerical prediction framework, a comprehensive study on typical bolted connections is conducted. Parameters relevant to connection behavior, including bolt spacing in the tensile and shear planes as well as the edge/end distances, are varied in the analysis. It is found that plastic bearing deformations facilitate shear fracture initiation, and significant uneven stress might occur along the shear failure path. Based on the findings, new design equations pertaining to bolted connection strength are proposed. The design equations not only indicate better correlation with the experimental data than current code equations but also reflect more accurately the actual failure mechanisms in the connections. The results can be useful for assessing in-service connections and achieving reliable yet economical structural design at a consistent safety level.

Global interest in seismic isolation technology continues to increase due to the satisfactory performance of isolated structures in recent earthquake events. In addition to the overall response of the structure, the design of the isolation devices is an important consideration. Reinforced elastomeric bearings are commonly used in seismic isolation applications and as bridge bearings. Relevant standards have been developed to guide designers on several critical design properties, such as the compression and bending modulus and the maximum shear strain due to compression and rotation. These standards commonly assume that the elastomer is incompressible and that the reinforcement is rigid and inextensible. In this paper, inconsistencies in design equations within and between selected standards are identified and discussed. It is shown that the aforementioned assumptions can result in significant error depending on the design and geometry of the bearing. To address these inconsistencies and to minimize the error, new design equations are derived and proposed. The proposed design equations include the compressibility of the elastomer and the extensibility of the reinforcement. The derivation of the proposed design equations is presented and the equations are compared against the analytical solutions and current design standards. It is shown that the proposed design equations are accurate, simple to use, and can address current inconsistencies in critical design properties.

Performance-based wind design (PBWD) allowing inelastic behavior under extreme wind load has only been recently considered for design of high-rise buildings. Unlike performance-based seismic design, there are few guidelines and research on inelastic wind design. Time-history wind loads for PBWD rely on wind tunnel tests. However, conducting wind tunnel tests for preliminary structural concepts may not be practical due to changes in design and cost. To address these concerns, the following topics were studied: initial design using an $R_W$ factor to introduce inelastic behavior; generation of time-history wind loads from power spectral density (PSD) functions for inelastic analysis including vertical distribution and maximum directional load occurrence, and a case study for wind resistance performance evaluation of a reinforced concrete building design using an $R_W$ factor of 1, 2, and 3.

Full-width tubular joints, consisting of chord and brace members of the same width (or diameter), have been frequently used in architectural, civil, and offshore structures owing to their higher load resistance compared with partial-width joints. In design standards, the full-width circular hollow section (CHS) joints have been treated as exhibiting chord plastification behavior similar to those of joints with lower brace-to-chord diameter ratios. However, in this study, it is found that for full-width CHS X-joints, the bearing or buckling behavior of the chord sidewall should also be considered for more accurate and consistent prediction of the joint strength. A new analytical model based on the column buckling approach, which accounts for both chord sidewall failure and chord plastification, is proposed. Further, it is shown that the proposed model could be regarded as more generic than the classical ring model that formed the analytical basis of current design standards. The proposed model is employed to derive a new design formula for CHS X-joints subjected to brace axial compression including high-strength steel. The application of the proposed design formula is limited to laterally restrained joints because the reduction in joint strength due to sidesway instability can be significant.

To investigate the performance of reinforced-concrete frames with buckling restrained braces (RCF-BRB) subjected to bidirectional earthquakes, a full-scale two-story RCF-BRB was tested using substructured pseudodynamic (PsD), quasistatic, and pushover techniques. This paper focuses on the structural modeling for the substructured PsD tests, and the control and measurement issues of the bidirectional loading system. To make a credible reproduction of the structural response using substructured PsD technique, an overlap modeling technique together with tuning the mass of the lamped-mass model and stiffness of the numerical substructure was employed to reduce errors caused by the incomplete boundary condition. The outer-loop control method based on Newton’s iteration method was introduced for the loading system, with the data from external displacement sensors as the feedback to avoid errors caused by possible gaps in the connection parts of the loading system. The redundancy issue, caused by the actuators outnumbering the degrees of freedom of the floor to be controlled, is addressed with a force-displacement mixed control technique. The three of four actuators were controlled in displacement mode, whereas the redundant one was in force mode. The force command to the redundant actuator was determined with the optimization criteria to minimize the loads relative to the capacities of the actuators. The working range of the displacement sensors is investigated using numerical and geometric approaches. Failure examples from numerical simulation and experiment were shown to emphasize the importance of proper arrangement of displacement sensors. A rearrangement of the displacement sensors was proposed for the pushover test to enlarge the working range. Time-history results of the prototype structure using the calibrated finite-element model show that the PsD substructure test results could represent seismic responses of the prototype structure. The measured mass-center displacements accurately tracked the target displacements throughout the test, indicating the effectiveness of the loading control and measuring system.

This paper presents experimental investigations on the seismic behavior of cross laminated timber (CLT) shear walls in a balloon frame configuration with various ledger assemblies attached at midheight. The tested system consisted of two seven-ply 191-mm-thick CLT panels with generic hold-downs, steel angle brackets, plywood surface splines, and nails as fasteners. A 2-story system was tested with a panel aspect ratio of $3:1$ with different steel and wood ledgers under monotonic and quasistatic reversed cyclic loading. Three ledgers were subsequently tested under vertical quasistatic monotonic loading to determine their remaining load-carrying capacity. The tests showed that the shear wall displacement was due to the rocking of the wall panels, which themselves behaved as rigid bodies with negligible in-plane deformations. When compared to the monotonic tests, the strength in reversed cyclic tests was up to 21% lower. The ledger did not impede the desired rocking behavior of the wall, nor did the rocking of the wall reduce the remaining gravity load-carrying capacity of the ledgers by more than 7%. Balloon-framed CLT shear walls can be detailed and designed using the Canadian standard specifications for platform-type construction.

Wind tunnel tests in an open terrain were carried out to study interference effects on peak pressure coefficients of one low-rise flat-roof building due to one high-rise building and similar low-rise buildings. The results demonstrate that amplification interference effects are significant on the minimum pressures at the edge of the low-rise building roof adjacent to the high-rise building and on the maximum pressures in the roof area away from the high-rise building, where the minimum pressure means the algebraic minimum with negative suction. Magnitudes of the envelope peak pressure coefficients on the low-rise building increase when the high-rise building height increases. The envelope minimum peak pressure coefficients in the roof middle area parallel to the high-rise building experience amplification effects at large building height and small spacing ratios, but other roof areas experience shielding effects at small spacing ratios, and interference factors of the envelope minimum peak pressure coefficients increase with the increase of the height and spacing ratios. When the spacing ratio is less than two, cases with large height ratios display amplification effects on the envelope maximum peak pressure coefficients, and amplification effects increase with the increase of the height ratio or the decrease of spacing ratio.

When a wide-flange section is exposed to close-in detonation, local and global deformation modes are developed due to a complex nonuniform pressure environment. The local deformation includes local distortion and rotation of the flanges, as well as deformation of the web, or even breaching near the web/flange junction. Experimental studies are presented to investigate the response of wide-flange sections to close-in detonations with and without stiffener plates and loaded about their weak and strong bending axes. The effectiveness of the stiffeners in mitigating damage is studied, and although they do have a positive effect, in some cases, the stiffeners do not contribute to the member resistance. Numerical models, validated against the test results, are used for a parametric study on the effect of the angle of incidence between the charge and the section, and the web-to-flange thickness ratio. It is found that a member needs to be analyzed for loading directions between the weak and strong bending axes to account for the maximum possible flange distortion. The thickness of the flange is irrelevant for the local web deformation but important for the global behavior of the member.

This article describes the use of coda wave measurements in a network of transducers for detecting stress changes and damage in large concrete structures. The applicability of the presented method is examined by performing four-point bending tests independently on two full-size concrete structures; i.e., a 6-m reinforced slab made in laboratory and a 30-m T-beam removed from a bridge after being in service for 15 years. The experiments demonstrate that stress changes and damage can be detected by coda waves for both laboratory and real-world concrete structures. The results also show that by setting up transducer networks appropriately, the tension and compression stress changes in concrete can be distinguished with a high degree of accuracy.

A steel delta girder (SDG) is formed by welding two inclined plates in the form of a V from the web to the compression flange of an I-section. Analytical, numerical, and experimental research on SDGs has shown that they possess enhanced flexural and shear capacities over traditional I-sections with comparable cross-sectional areas. In this paper, three-dimensional nonlinear inelastic finite-element models that take into consideration the effects of initial geometrical imperfections and residual stresses are developed to investigate the inelastic lateral-torsional buckling and shear behavior of simply-supported SDGs under uniform bending and pure shear. Using European H- and I-sections as base cross sections, the analyses cover a wide range of SDG dimensions and inclined stiffener configurations. The results of these analyses demonstrate that the flexural capacities of SDGs can be represented by two of the existing EuroCode 3 (EC3) buckling curves. Design equations for the shear capacity of SDGs are then developed and proposed in accordance with EC3 provisions. Finally, design recommendations for selecting the proper inclined plate dimensions and configurations within the delta region of SDGs are provided.

Wind load is the designed control load for super-large cooling tower (SLCT) structures. Studies on wind resistance of those structures have focused mainly on normal winds, not on the influence of strong typhoons, or in particular the values of suction. To study the suction distribution and action mechanism of flow fields in an SLCT in typhoon conditions, in this study a high temporal–spatial resolution simulation of Typhoon Megi was done using a mesoscale weather research and forecasting (WRF) model with a multiple nesting structure. The wind velocity profile in the simulated region was gained through least squares fit. The research object was the world’s highest cooling tower (220 m) at the Lu’an power plant in Shanxi Province, China. Three-dimensional (3D) computational fluid dynamics (CFD) wind field simulations of this tower in normal-wind and typhoon conditions were done based on a mesoscale–microscale nesting technology. A comparative analysis on the 3D effect of wind loads on the internal surface of an SLCT in a typhoon was also done, as was a summary of the meridian and circumferential distribution laws of the internal pressure coefficients. Differences on flow field characteristics, pressure coefficients, drag coefficients, and wind resistance in the tower structure in normal-wind and typhoon conditions and relative causes were investigated. Finally, the recommended values of suction in an SLCT in typhoon conditions are proposed. Results demonstrate that a WRF–CFD coupling model can effectively simulate the near-surface 3D wind field of an SLCT in typhoon conditions. Compared with a normal wind, the high wind velocity and strong turbulence of a typhoon causes larger-scale vortices inside the cooling tower, a more turbulent airflow on the leeward side, and a longer development area of vortices. In typhoon conditions, the internal pressure coefficient of the tower increased when the ventilation rate of the louver was 15%, 30%, and 100%. The overall internal pressure coefficient was found to be $-0.61$, $-0.36$, $-0.34$, and $-0.42$ when the ventilation rates of the louver are 0%, 15%, 30%, and 100%, respectively.

With the advancement and wide availability of digital video cameras, compounded with the development and enhancement of computer vision methods, vision-based sensing using a video camera as a sensor is promising to become a viable alternative and complementary approach to conventional structural health monitoring (SHM). Among many video analytics methods, no single method is effective for various practical SHM applications using a video camera as a sensor. Not only is it vitally important to understand the effectiveness and shortcomings of the methods, but also there is a need for developing an integrated framework and software tool to enable structural engineers to apply the suitable method for the SHM case at hand. To bridge the gap between the research and practical vision-based SHM applications, this paper presents a unified video analysis framework that integrates both the phase-based algorithm and template matching methods for processing SHM videos recorded using either industrial or consumer types of cameras. The methods have been implemented and integrated into a versatile software tool for extracting structural responses such as displacements, velocities, and accelerations at the points of interest on a structure. The integrated tool enables us to conduct a comparison study of displacement and tilt measurements for a reinforced concrete wall tested in a large structural laboratory and a highway bridge test in the field. The results obtained for the tests have been compared with measurements by conventional sensors. The comparison reveals the advantages and limitations of the phase-based algorithm and the template matching methods. The integrated framework, together with the lessons learned from the comprehensive comparison study, facilitates effective SHM applications using a video camera as a sensor in practice.